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Life Sciences Grade 12

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					Life Sciences
  Grade 12
                           Table of Contents
                                                                     Page
                                                                     number
Module 1
Unit 1       Cells, tissues and molecular studies
             (Genetics)
Chapter 1    DNA and RNA                                                4
Chapter 2    Transcription and translation                              10
Chapter 3    Meiosis                                                    13
Chapter 4    Stem cells                                                 19
Chapter 5    Mutation                                                   22
Chapter 6    Inheritance and genetic disease                            25
Chapter 7    Discovery of the principles of heredity                    27
Chapter 8    Concepts of inheritance                                    31
Chapter 9    Types of dominance in genes                                44
Chapter 10   Multiple alleles                                           49
Chapter 11   Sex chromosomes and alleles                                54
Chapter 12   Genetic engineering                                        61
Chapter 13   Genetic engineering of plants                              64
Chapter 14   Genetic fingerprinting                                     74

Unit 2       Structure, control and procession in basic life
             systems (Reproduction)
Chapter 1    The human reproductive organs: the male
                                                                        77
             reproductive system
Chapter 2    The human reproductive organs: the female
                                                                        83
             reproductive system
Chapter 3    The formation of male and female sex cells                 90
Chapter 4    Reproductive hormones                                      93
Chapter 5    The menstrual cycle                                        98
Chapter 6    Conception, embryonic development and
                                                                       104
             implantation
Chapter 7    Birth, antenatal and postnatal care                       114
Chapter 8    Controlling human fertility                               120
Chapter 9    Reproduction: related diseases                            127
Chapter 10   Reproduction of plants                                    132

Module 2
Unit 1       Diversity, change and continuity
Chapter 1    Origin of the species                                     140
Chapter 2    Inbreeding and outbreeding                                142
Chapter 3    The formation of species (a)                              144
Chapter 4    The formation of species (b)                              146

Unit 2       Diversity, change and continuity
Chapter 1    The cradle of humankind – South Africa                    149
Chapter 2    The origin of humankind (a)                               151
Chapter 3    The origin of humankind (b)                               156

                Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                 Page 2 of 233
Chapter 4   Human migration                                          169

Unit 3      Diversity, change and continuity
Chapter 1   Fossils as evidence of ancient life                      179
Chapter 2   Mass extinction                                          184
Chapter 3   Popular theories of mass extinction                      186
Chapter 4   Ice Age                                                  189

Module 3
Unit 1      Environmental studies
Chapter 1   Biodiversity and local indigenous resources              199
Chapter 2   Local environmental issues: exploitation of local
                                                                     201
            indigenous resources (a)
Chapter 3   Local environmental issues: exploitation of local
                                                                     203
            indigenous resources (b)
Chapter 4   Pollution: Designing a clean-air environment             209

Unit 2      Environmental studies
Chapter 1   HIV/Aids                                                 217
Chapter 2   Aids: Antiretroviral drugs (a)                           224
Chapter 3   Aids: Antiretroviral drugs (b)                           226

Glossary




                Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                 Page 3 of 233
 Unit 1
Activity 1
 Planning
Documents
                                                                                             SUBJECT FRAMEWORK: YEAR PLAN

School:                                                                                Year:                                                                             Term/Weeks:
                      Grade 10: Module 1                                                                      Grade 11: Module 1                                                                 Grade 12: Module 1
 Duration of                        Learning                                            Duration of         36           Learning                                         Duration of        40          Learning
                   36 hours                                10.1, 10.2, 10.3                                                                       11.1, 11.2, 11.3                                                                12.1, 12.2, 12.3
   module:                         outcomes:                                              module:          hours        outcomes:                                            module:        hours       outcomes:
      Learning                                                                                Learning                                                                         Learning
                       Assessment standard                     Content                                          Assessment standard                    Content                                   Assessment standard                     Content
     Outcomes                                                                                Outcomes                                                                         Outcomes
10.1: Scientific     10.1.1: Identifying and       Introduction to Life Sciences.      11.1: Scientific        11.1.1: Identifying and     Micro-organisms.              12.1: Scientific     12.1.1: Identifying and        DNA and RNA.
inquiry and          questioning phenomena         How science works.                  inquiry and             questioning phenomena       Viruses.                      inquiry and          questioning phenomena          Transcription and translation.
problem solving      and planning an               Safety rules in the classroom.      problem-solving         and planning an             HIV/Aids.                     problem-solving      and planning an                Meiosis.
skills: The          investigation.                Apparatus in the laboratory.        skills: The learner     investigation.              Bacteria.                     skills: The          investigation.                 Stem cells.
learner is able to   (a): Identify and question    Biosphere and inter-connected       is able to              (a): Identify phenomena     Drug resistance.              learner is able to   (a): Generate and question     Mutation.
confidently          phenomena.                    components between the              confidently explore     involving one variable to   Tuberculosis.                 confidently          hypotheses based on            Inheritance and genetic disease.
explore and          (c): Consider implications    components of the global            and investigate         be tested.                  Fungi (a).                    explore and          identified phenomena for       Discovery of the principles of
investigate          of investigative              ecosystem.                          phenomena               (b): Design simple tests    Fungi (b).                    investigate          situations involving more      heredity.
phenomena            procedures in a safe          Biomes of South Africa.             relevant to Life        to measure the effects      Protists.                     phenomena            than one variable.             Concepts of inheritance.
relevant to Life     environment.                  Ecosystems.                         Sciences by using       of this variable.           Malaria.                      relevant to Life     (b): Design tests and/or       Types of dominance in genes.
Sciences by          10.1.2: Conducting an         Human influence on ecosystems in    inquiry, problem-       (c): Identify advantages    Immunity.                     Sciences by          surveys to investigate         Multiple alleles.
using inquiry,       investigation by collecting   the biosphere.                      solving, critical       and limitations of          Discovery of vaccination.     using inquiry,       these variables.               Sex chromosomes and alleles.
problem-solving,     and manipulating data.        Energy flow through an              thinking and other      experimental design.        Vaccination (immunisation).   problem-solving,     (c): Evaluate the              Genetic engineering.
critical thinking    (a): Systematically and       ecosystem.                          skills.                 11.1.2: Conducting an                                     critical thinking    experimental design.           Genetic engineering of plants.
and other skills.    accurately collect data       Biochemical cycles.                                         investigation by                                          and other skills.    12.1.2: Conducting an          Genetic fingerprinting.
                     using selected                Relationship of biogeochemical                              collecting and                                                                 investigation by collecting    The human reproductive organs:
                     instruments and/or            cycles with current environmental                           manipulating data.                                                             and manipulating data.         the male and female reproductive
                     techniques and following      conditions.                                                 (a): Systematically and                                                        (a): Compare instruments       system.
                     instructions.                 Ecotourism.                                                 accurately collect data                                                        and techniques to improve      The formation of male and female
                     (b): Display and                                                                          using selected                                                                 the accuracy and reliability   sex cells.
                     summarise the data                                                                        instruments and/or                                                             of data collection.            Reproductive hormones.
                     collected.                                                                                techniques.                                                                    (b): Manipulate data in the    The menstrual cycle.
                     10.1.3: Analysing,                                                                        (b): Select a type of                                                          investigation to reveal        Conception, embryonic
                     synthesising, evaluating                                                                  display that                                                                   patterns.                      development and implantation.
                     data and communicating                                                                    communicates the data                                                          (d): Allow for irregular       Birth, antenatal and postnatal
                     findings.                                                                                 effectively.                                                                   observations and               care.
                     (a): Analyse, synthesise,                                                                 11.1.3: Analysing,                                                             measurements when              Controlling human fertility.
                     evaluate data and                                                                         synthesising, evaluating                                                       displaying data.               Reproduction: related diseases.
                     communicate findings.                                                                     data and communicate                                                           12.1.3: Analysing,             Reproduction of plants.
                                                                                                               findings.                                                                      synthesising, evaluating
                                                                                                               (a): Compare data and                                                          data and communicating
                                                                                                               construct meaning to                                                           findings.
                                                                                                               explain findings.                                                              (a): Critically analyse,
                                                                                                               (b): Draw conclusions                                                          reflect on and evaluate the
                                                                                                               and recognise                                                                  findings.
                                                                                                               inconsistencies in the                                                         (b): Explain patterns in the
                                                                                                               data.                                                                          data in terms of
                                                                                                               (c): Assess the value of                                                       knowledge.
                                                                                                               the experimental                                                               (c): Provide conclusions
                                                                                                               process and                                                                    that show awareness of
                                                                                                               communicate findings.                                                          uncertainty in data.
                                                                                                                                                                                              (d): Suggest specific
                                                                                                                                                                                              changes that would
                                                                                                                                                                                              improve the techniques
                                                                                                                                                                                              used.




                                                                                            Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                                                                                                         Page 63 of 120
     Learning                                                      Learning                                                       Learning
                      Assessment standard          Content                           Assessment standard           Content                         Assessment standard          Content
    Outcomes                                                      Outcomes                                                       Outcomes
10.2:                10.2.1: Accessing                       11.2: Construction      11.2.1: Accessing                       12.2:                12.2.1: Accessing
Construction         knowledge.                              and application of      knowledge.                              Construction         knowledge.
and application      (a): Use a prescribed                   Life Sciences           (a): Use various                        and application      (a): Use various methods
of Life Sciences     method to access                        knowledge: The          methods and sources to                  of Life Sciences     and sources to access
knowledge: The       information.                            learner is able to      access information.                     knowledge: The       relevant information from
learner is able to   10.2.2: Interpreting and                access, interpret,      11.2.2: Interpreting and                learner is able to   a variety of contexts.
access, interpret,   making meaning of                       construct and use       making meaning of                       access, interpret,   12.2.2: Interpreting and
construct and use    knowledge in Life                       Life Sciences           knowledge in Life                       construct and use    making meaning of
Life Sciences        Sciences.                               concepts to explain     Sciences.                               Life Sciences        knowledge of Life
concepts to          (a): Identify concepts,                 phenomena               (a): Identify, describe                 concepts to          Sciences.
explain              principles, laws, theories              relevant to Life        and explain concepts,                   explain              (a): Interpret, organise,
phenomena            and models of Life                      Sciences.               principles, laws,                       phenomena            analyse, compare and
relevant to Life     Sciences in the context of                                      theories and models by                  relevant to Life     evaluate concepts,
Sciences.            everyday life.                                                  illustrating relationships.             Sciences.            principles, laws, theories
                     (b): Describe and explain                                       (b): Evaluate concepts,                                      and models and their
                     concepts, principles,                                           principles, laws,                                            application in a variety of
                     laws, theories and                                              theories and models.                                         contexts.
                     models.                                                         11.2.3: Showing an                                           12.2.3: Showing an
                     10.2.3: Showing an                                              understanding of the                                         understanding of the
                     understanding of the                                            application of Life                                          application of Life
                     application of Life                                             Sciences knowledge in                                        Sciences knowledge in
                     Sciences knowledge in                                           everyday life.                                               everyday life.
                     everyday life.                                                  (a): Analyse and                                             (a): Evaluate and
                     (a): Organise, analyse                                          evaluate the costs and                                       present an application of
                     and interpret concepts,                                         benefits of applied Life                                     Life Sciences knowledge.
                     principles, laws, theories                                      Sciences knowledge.                     12.3: Life           12.3.1: Exploring and
                     and models of Life                      11.3: Life              11.3.1: Exploring and                   Sciences,            evaluating scientific ideas
                     Sciences in the context of              Sciences,               evaluating scientific                   Technology,          of past and present
                     everyday life.                          Technology,             ideas of past and                       Environment          cultures.
10.3: Life           10.3.1: Exploring and                   Environment and         present cultures.                       and Society: The     (a): Critically evaluate
Sciences,            evaluating scientific ideas             Society: The            (a): Compare scientific                 learner is able to   scientific ideas and
Technology,          of past and present                     learner is able to      ideas and indigenous                    demonstrate an       indigenous knowledge of
Environment          cultures.                               demonstrate an          knowledge of past and                   understanding of     past and present cultures.
and Society:         (a): Identify and                       understanding of        present cultures.                       the nature of        12.3.2: Comparing and
The learner is       investigate scientific                  the nature of           11.3.2: Comparing and                   science, the         evaluating the uses and
able to              ideas and indigenous                    science, the            evaluating the uses and                 influence of         development of resources
demonstrate an       knowledge of past and                   influence of ethics     development of                          ethics and biases    and products, and their
understanding of     present cultures.                       and biases in the       resources and products,                 in the Life          impact on the
the nature of        10.3.3: Comparing the                   Life Sciences, and      and their impact on the                 Sciences, and the    environment and society.
science, the         influence of different                  the interrelationship   environment and                         interrelationship    (a): Analyse and
influence of         beliefs, attitudes and                  of science,             society.                                of science,          evaluate different ways in
ethics and biases    values on scientific                    technology,             (a): Compare different                  technology,          which resources are used
in the Life          knowledge.                              indigenous              ways in which                           indigenous           in the development of
Sciences, and the    (a): Analyse and describe               knowledge, the          resources are used in                   knowledge, the       biotechnological
interrelationship    the influence of different              environment and         the development of                      environment and      products, and make
of science,          beliefs, attitudes and                  society.                biotechnological                        society.             informed decisions about
technology,          values on scientific                                            products, and analyse                                        their use and
indigenous           knowledge and its                                               the impacts on the                                           management in society
knowledge, the       application to society.                                         environment and                                              for a healthy, sustainable
environment and                                                                      society.                                                     environment.
society.




                                                                  Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                                                                                Page 64 of 120
Learning                                         Learning                                                    Learning
           Assessment standard   Content                           Assessment standard        Content                         Assessment standard        Content
Outcomes                                        Outcomes                                                    Outcomes
                                           11.3: Life              11.3.3: Comparing the                12.3: Life           12.3.3: Comparing the
                                           Sciences,               influence of different               Sciences,            influence of different
                                           Technology,             beliefs, attitudes and               Technology,          beliefs, attitudes and
                                           Environment and         values on scientific                 Environment          values on scientific
                                           Society: The            knowledge.                           and Society: The     knowledge.
                                           learner is able to      (a): Compare scientific              learner is able to   (a): critically evaluate
                                           demonstrate an          ideas and indigenous                 demonstrate an       and take a justifiable
                                           understanding of        knowledge of past and                understanding of     position on beliefs,
                                           the nature of           present cultures.                    the nature of        attitudes and values that
                                           science, the                                                 science, the         influence developed
                                           influence of ethics                                          influence of         scientific and
                                           and biases in the                                            ethics and biases    technological knowledge
                                           Life Sciences, and                                           in the Life          and their application in
                                           the interrelationship                                        Sciences, and the    society.
                                           of science,                                                  interrelationship
                                           technology,                                                  of science,
                                           indigenous                                                   technology,
                                           knowledge, the                                               indigenous
                                           environment and                                              knowledge, the
                                           society.                                                     environment and
                                                                                                        society.




                                                Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                                                             Page 65 of 120
                                         WORK SCHEDULE

           Module 1
  Week:
                        Unit                  Learning
   Date                and/or              Outcomes and                                            Assessment
started:                          Time                                     Content
                      chapter               Assessment                                               Tasks
   Date               numbers                Standards
 ended:
                        U1        640         12.1.3(a)                  DNA and RNA                    n/a
                       C1 – 7     min         12.2.1(a)           Transcription and translation
                                              12.2.2(a)                      Meiosis
                                              12.2.3(a)                    Stem cells
                                              12.3.2(a)                     Mutation
                                              12.3.3(a)         Inheritance and genetic disease
                                                                  Discovery of the principles of
                                                                            heredity

  Week:
                        Unit                  Learning
   Date                and/or              Outcomes and                                            Assessment
started:                          Time                                     Content
                      chapter               Assessment                                               Tasks
   Date               numbers                Standards
 ended:
                        U1        810         12.1.1(a)           Concepts of inheritance          Practical task
                      C8 – 14     min         12.1.2(a)         Types of dominance in genes
                                              12.1.3(a)                Multiple alleles
                                              12.2.1(a)         Sex chromosomes and alleles
                                              12.2.2(a)             Genetic engineering
                                              12.2.3(a)         Genetic engineering of plants
                                              12.3.1(a)             Genetic fingerprinting
                                              12.3.4(a)
  Week:
                        Unit                  Learning
   Date                and/or              Outcomes and                                            Assessment
started:                          Time                                     Content
                      chapter               Assessment                                               Tasks
   Date               numbers                Standards
 ended:
                        U2        450       12.1.3(a), (b)         The human reproductive               n/a
                       C1 – 5     min         12.2.1(a)          organs: the male and female
                                              12.2.2(a)              reproductive system
                                              12.2.3(a)           The formation of male and
                                              12.3.1(a)                female sex cells
                                              12.3.3(a)            Reproductive hormones
                                                                     The menstrual cycle

  Week:
                        Unit                  Learning
   Date                and/or              Outcomes and                                            Assessment
started:                          Time                                     Content
                      chapter               Assessment                                               Tasks
   Date               numbers                Standards
 ended:
                        U2        510     12.1.1(a), (b), (c)        Conception, embryonic              n/a
                      C6 – 10     min       12.1.2(b), (d)      development and implantation
                                           12.1.3(a), (b),       Birth, antenatal and postnatal
                                               (c), (d)                       care
                                              12.2.1(a)            Controlling human fertility
                                              12.2.2(a)         Reproduction: related diseases
                                              12.2.3(a)              Reproduction of plants




                            Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                              Page 74 of 120
                                                                1


                                   LESSON PLANS
Unit number:    1
Chapter                Duration        90 min   Planned                  Actual
number:         1      of                       date:                    date:
                       chapter:

Learning Outcomes and Assessment Standards:
12.2.1(a); 12.2.2(a); 12.2.3(a)

Content:
DNA and RNA

Activity:
Study information
Complete a crossword puzzle
Draw a table
Write a report

Resources:
n/a

Assessment
Tasks:
n/a

                              For assessment by the teacher:
Remedial:
Enrichment:
Reflection:
Homework:




                    Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                       Page 77 of 120
       P

  Learning and
Teaching Support
 Material (LTSM)
                                                             1



                                               1



                    1


DNA and RNA

1.   Study the following information about chromosomes, DNA and RNA and
     complete the activities that follow.




A.   Chromosomes and the cell nucleus

     Chromosomes are found in the nucleus of a cell. A chromosome consists of
     DNA and proteins, known as histones. The nucleus is found in the cell of
     living organisms. The nucleus is very important in a cell because it controls
     the functions in the cell and without it the cell is unable to perform normally.
     The nucleus controls the metabolism in the cell, the structure of the cell, and
     carries the hereditary characteristics of the cell.

     The nucleus is round or oval in shape. It is enclosed in a double nuclear
     membrane with pores, and is filled with nucleoplasm. The pores play a role in
     the exchange of substances between the nucleus and the cell content. In the
     nucleus, there are dark round bodies known as the nucleolus (plural: nucleoli).
     A network of fine threads, known as chromatin, is found in the nucleoplasm.

     If cell division takes place, the chromatin become less dense and separate
     threads, known as chromosomes, are more visible. A very important
     component of these chromosomes is DNA.

I.   Deoxyribonucleic acid – DNA
     DNA plays an important role in the living cell, especially in the carrying of
     hereditary characteristics from one organism to its offspring. It also plays an
     important role in the regulation of the structure of protein formation during
     protein synthesis. Chromosomes contain DNA and proteins known as
     histones. It is believed that DNA is twisted around these histones.




                  Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                   Page 4 of 233
         Figure 1: The structure of a chromosome with a deoxyribonucleic
                               acid (DNA) unwinding




(i)   The structure of DNA

      James Watson, a young postdoctoral student from Indiana University, and
      Francis Crick, an energetic researcher at Cambridge University, put together a
      model that fitted all the facts about DNA they had gathered from resources. In
      1953 they discovered the structure of DNA.

      Their model of DNA has a double helix form, (similar to a spiral staircase). If
      this DNA model is ‘untwisted’, it has the shape of a ladder. DNA is very
      small. It is a polymer, because it is made up of a large amount of identical or
      near-identical units, known as monomers. DNA consists of four different
      nucleotides, each of which consists of three parts.

•     Sugar part

      This sugar part is known as deoxyribose.

•     Phosphate part

      A phosphate group binds the sugar parts together, i.e. it is situated between the
      sugar parts.

•     Nitrogen base part

      Four different nitrogen bases are found in the DNA molecule. They are
      connected to the sugar part. The four bases are:

      Guanine (G) and adenine (A) – known as purine bases; and

      Thymine (T) and cytosine (C) – known as pyrimidine bases. They are smaller
      molecules than the purine bases.




                   Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                    Page 5 of 233
                               Figure 2: DNA nucleotides



            Sugar            Nitrogen base             Adenine                 Sugar
         (deoxyribose)         (Thymine)                                      (deoxy-
                                                                              ribose)




             Phos-                                                            Phos-
             phate                                                            phate




                     Nucleotide                                  Nucleotide

      DNA consists of two parallel strands of nucleotides. As mentioned they are
      joined to each other by hydrogen bonds to form a ladder-shaped structure. At
      each twist of the DNA ladder are two bases (A = T and C = G) connected to a
      sugar (deoxyribose) and a sugar connected to a phosphate.

      Adenine (A) always connects to thymine (T) and cytosine (C) always connects
      to guanine (G). These connections occur in equal numbers of guanine and
      cytosine and equal numbers of adenine and thymine.

      Various and different combinations of these base pairs along a chromosome
      are called genes and each gene controls the different parts of the body’s
      functioning and structure. RNA can be seen as an ‘assistant’ of DNA.

II.   Ribonucleic acid – RNA

      RNA is found in the nucleus, nucleolus, and the ribosomes and plays an
      important role in protein synthesis. Just like DNA, RNA also consists of
      four different kinds of nucleotides. In other aspects, RNA differs from DNA.

      RNA consists of only a single strand. RNA contains a sugar known as ribose
      and a nitrogen base known as uracil (U) instead of thymine (T). The four
      bases – adenine (A); uracil (U); cytosine (C) and guanine (G) occur in any
      number on a single strand.




                     Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                       Page 6 of 233
                           Figure 3: RNA nucleotides




                          Sugar            Guanine
                         (ribose)

                                                                 Nucleotide

                           Phos-
                           phate




                                          Nitrogen
                          Sugar            base
                         (ribose)         (uracil)


                                                                  Nucleotide

                           Phos-
                           phate




     Different types of RNA are found, each of which fulfils a different function –
     ribosomal RNA (rRNA); messenger RNA (mRNA) and transfer RNA (tRNA).

     The condition known as gout is the result of a build-up in the tissues of uric
     acid. Uric acid is a metabolic by-product formed from the destruction of DNA
     molecules. Uric acid is formed from the pyrimidine and, more especially, the
     larger purine bases. Slow excretion of uric acid, drinking insufficient water,
     and eating foods high in purines can lead to an attack of gout which manifests
     itself as stiffness in muscles and painful joints.


2.   Complete the crossword puzzle, by using the clues:




                 Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                    Page 7 of 233
      Across
2.    This is where the chromosomes are found in a cell
4.    A network of fine threads found in the nucleoplasm
7.    This type of allele hides/masks the recessive allele's traits
8.    This plays an important role in protein synthesis
9.    Proteins on a chromosome are known as this
10.   This means a gamete containing only one set of chromosomes
11.   Genes are found on these structures
12.   This is known as a pyrimidine base

      Down
1.    The form of DNA
3.    These structures are also called sex cells
5.    Cytosine (C) connects to this
6.    The part of DNA that binds the sugar parts together
7.    Chromosomes consist of this
9.    This type of bond joins two strands of nucleotides




                  Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                   Page 8 of 233
3.     Answer the following questions based on your knowledge and further research
       (if needed) in your workbook.
3.1    Access the knowledge contained in the information block, redraw the table
       below in your workbook and compare the structures of DNA and RNA with
       each other.
                      DNA                                  RNA



3.2   Write a report on how DNA can be used to provide incriminating evidence in
      a murder or rape case, or identify the parents of a lost child. Your report must
      be at least 150 – 200 words and cover the following:
3.2.1 A short interpretation of DNA and a brief analysis of its place in a forensic
      case.
3.2.2 A comparison of DNA investigations and previous methods of ascertaining
      information.
3.2.3 An evaluation or critique of DNA in current use and its future in forensic and
      other applications.

                                        RESEARCH


1.     You may use all the relevant information blocks in this Learner’s Book as a
       source of information but also try to find more information in books, reference
       books and on the Internet. You may also ask your teacher for information.
2.     Use drawings, cuttings or photographs to make your written research more
       visually attractive.
3.     Find the key words or main idea of what you are researching.
4.     Consult the index of books, headings of articles or the information blocks to
       find the key words.
5.     Do some inspectional reading. Inspectional reading is the art of skimming
       systematically through a passage. Skim through an article to get the main
       idea. Then return to passages relevant to your research.
6.     Make notes. To assemble these notes more easily, they should be written on
       separate sheets of paper, each with a heading so that they can later be arranged
       under different topics. For example:
7.     Now write all relevant information you come across under each heading.
8.     The key to success in making notes is to write down only the main ideas and
       not to copy the article or information word for word.
9.     Content ideas are now compared and combined together. Rewrite them from
       your notes on the separate sheets into a final format. It is important to avoid
       repetition.
10.    Arrange the information in essay form using your own words.
11.    Refer to resources within your text, for example: Peters (1997) says that
       South African culture originated in… etc.
12.    Remember to keep a list of all reference books, Internet addresses, magazines
       and the authors responsible for the articles you used.




                    Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                     Page 9 of 233
13.    Your final format for your research should include the following sections:

•      A title page
•      Table of Contents
•      Introduction
•      Body of research
•      Conclusion
•      Bibliography

14.   You have worked at the body of research in this activity. Your list of
      reference books and articles will form part of your bibliography.



                      2

Transcription and translation

1.     Study the following information on how proteins are formed and complete the
       activities that follow.




A.     The formation of RNA strings – transcription

       Transcription takes place when RNA is made from the ‘code’ found in the
       DNA. As mentioned, DNA is a double-stranded molecule in the shape of a
       spiral staircase. DNA consists of the four nitrogen bases – adenine, guanine,
       cytosine and thymine.

      The base sequence is the order in which these nitrogen bases follow each other
      on the DNA strand. Different organisms have different base sequences.

       Transcription takes place in the nucleus of a cell. The DNA molecule unwinds
       and the two strands separate from each other in certain regions. The
       nucleotide bases of the DNA will serve as a template (structural pattern) for
       the ‘building’ of the RNA strand. The molecules used for the formation of
       RNA are found in the cell’s pool of free nucleotides. These free nucleotides
       form pairs with the nucleotides on the DNA strand. Uracil, found in RNA,
       combines with the adenine in the DNA strand.

       This ‘matching’ of nucleotides follows the base-pairing rule – adenine with
       uracil, and cytosine with guanine. After a RNA-strand has formed, it breaks
       away from the DNA template. The DNA rewinds into a double helix again.
       This single strand of RNA moves to the cytoplasm where translation, i.e. the
       formation of proteins, will take place.



                   Grade 12 Life Sciences Learner’s Book Module 1 – 3
                                   Page 10 of 233
                                                              1


                                                1


                     1


ASSIGNMENT

DNA and RNA
(12.2.1(a); 12.2.2(a); 12.2.3(a))

1.     Learners read the information about DNA and RNA in the Learner’s Book.

2.     They complete the crossword puzzle, by using the clues.




3.     The learners answer the questions based on their knowledge and further
       research.
3.1    They access the knowledge contained in the information block and redraw the
       table which they use to compare the structures of DNA and RNA with each
       other. They do this in their workbooks. (12.2.1(a); 12.2.2(a); 12.2.3(a))


                   Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                      Page 6 of 120
                          DNA                                           RNA
      Carriers of hereditary characteristics from one Carries the code for the
      organism to the offspring.                      formation/synthesis of proteins
                                                      in an organism.
      Found mainly in the nucleus of the cell.        Found in the nucleus and
                                                      cytoplasm of the cell.
      Double helix shape/strand.                      Single strand.
      Long strand of DNA.                             Short strand of RNA.
      Sugar part known as deoxyribose.                Sugar part known as ribose.
      Four nitrogen bases, namely:                    Four nitrogen bases, namely:
      guanine (G), adenine (A); acytosine (C) and guanine (G), adenine (A);
      thymine (T).                                    cytosine (C) and uracil (U)
                                                      (instead of thymine (T)).
      Bases occur in pairs: A = T and C = G           Only a single strand, but
                                                      during formation of RNA:
                                                      A = U and C = G.
      Bases occur in equal numbers;                   Bases occur in any number.
      A = T and C = G.

3.2    Learners write a report on how DNA can be used to provide incriminating
       evidence in a murder or rape case, or identify the parents of a lost child. The
       following is an example of the answer:

       In the case of murder, blood, hair or skin samples can be matched to the
       alleged suspect of the crime, or to the murder victim and a match made using
       DNA finger printing to establish whether or not there is a correlation between
       the suspect and the sample found on the victim. In the case of a rape, semen
       or hair samples can be collected from the victim and these analysed for DNA
       matching. DNA can be used so that it will provide a consistent record of the
       gene composition of parent and child. So if the DNA of the child is matched
       with that of either one of the two parents, there will be up to 99% probability
       prove that a child belongs to a specific parent. DNA samples can be taken
       from any part of the body, but usually hair samples or skin samples are taken.

       Their report must be at least 150 – 200 words and should cover the topics
       stipulated in the Learner’s Book.

3.2.1 The place of DNA analysis in forensic cases has a vital role to play in that
      accurate assessments can be made of the probability of whether or not a
      suspect of a crime can be matched to a particular case. The DNA is analysed
      to find the genetic sequence.




                   Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                      Page 7 of 120
        Genetic fingerprinting exploits highly variable repeating sequences called
        minisatellites. Two unrelated humans will be likely to have different numbers
        of minisatellites at a given locus. By using genetic fingerprinting to detect the
        number of repeats at several loci, it is possible to establish a match that is
        extremely unlikely to have arisen by coincidence, except in the case of
        identical twins, who will have identical genetic profiles. If there is no match
        of hair, skin, blood samples in a forensic investigation, then there can be no
        connection between the victim and the suspect.

3.2.2   Before the sequence of the genes in human DNA was accurately analysed, the
        only other way of connecting someone to a murder or rape case, was blood
        grouping or other clumsy methods of investigation that proved to be relatively
        inaccurate scientifically. With DNA fingerprinting, forensic investigation has
        taken a new dimension because it provides accurate evidence.

3.2.3   DNA fingerprinting has an obvious place in forensic investigations in that it
        can connect victim and suspect or can place a suspect of a crime at a specific
        place, by analysing hair, skin, blood samples found at the scene. DNA
        fingerprinting also has a place in modern society in that it can be used to
        establish parenthood and can be used to predict possible diseases that might be
        latent in individuals.

                       2


ASSIGNMENT

Transcription and translation
(12.2.1(a); 12.2.2(a); 12.2.3(a))

1.      Learners read the information on how proteins are formed in their Learner’s
        Books.

2.    The learners answer the questions in their workbooks.
2.1   Read the question with the learners.
2.1.1 CA = GGT; UUG = AAC; AUA = TAT; CGA = GCT
2.1.2 Codons are base triplets of mRNA which serve as codes for protein synthesis.
      They are found in the cytoplasm of cells.
2.1.3 GGU, AAC, UAU and GCU.
2.1.4
(a)   CCA – GGT – Glycine
      UUG – AAC – Asparganine
      AUA – TAT – Tyrosine
      CGA – GCT – Alanine

(b) Glycine    Asparganine       Tyrosine     Alanine




                     Grade 12 Life Sciences Teacher’s Book Module 1 – 3
                                        Page 8 of 120

				
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