Structure and Function of DNA Study Guide
RNA Amino Acid
Mutation Double Helix
Selective Breeding Genetic Code
1. DNA is the information molecule.
DNA stores the information necessary for a cell to put together the
correct sequence of amino acids needed to produce specific proteins.
DNA is a spiral molecule made up of nucleotide bases: adenine,
thymine, cytosine and guanine. It is the sequence of these bases that
forms to code for making proteins.
When a cell divides, DNA replicates itself. The DNA molecule
separates and free nucleotides match up to each open strand.
2. RNA is needed to make proteins.
There are 3 kinds of RNA; messenger RNA, transfer RNA, and
ribosomal RNA and they are used to make proteins. Transferring
information from DNA to RNA is known as transcription. During this
process, a strand of DNA is used to make a single strand of mRNA.
The assembly of amino acids in their proper sequence to form a
protein molecule is known as translation. Proteins are made on
3. DNA sequences can change.
Variations in DNA are what give organisms different characteristics.
Any change to DNA is a mutation. Mutations can cause no effect, have
a minor effect, or a great effect. Some mutations are harmful, such as
those that result in genetic disorders. Other mutations can be
beneficial if they improve and organism’s ability to survive or resist
4. Mutations can cause genetic disorders.
Mutations that affect the normal functioning of a cell can result in
genetic diseases that are passed from parent to offspring.
Pedigrees are diagrams of family relationships that include two or
more generations. Genetic diseases can be traced through a pedigree.
5. Changes in DNA can change an organism.
Selective Breeding is controlled by crossing two organisms with
desirable traits to produce those traits.
Genetic Engineering is a process that allows humans to change the
DNA of an organism by isolating it, changing it, and returning it to the
organism or a different organism. The genetically modified organisms
have the desired traits.
6. There are risks and benefits associated with genetic engineering and
Genetic engineering allows scientists to produce organisms such as
plants that produce more food, or are resistant to certain diseases or
insects, or animals that are modified to grow faster. Scientists are
uncertain how the genetically modified organisms might affect natural
populations if they are interbred.
Benefits of Selective Breeding
a. No complicated techniques/equipment, just need knowledge of
b. Can be used to produce new crop varieties
c. Does not involve danger of ill effects that may result from
transferring genes across species
Risks of selective breeding
a. Lowers genetic diversity of a crop and weakens the crop if the
environmental conditions change
b. It is limited to related species
Benefits of Genetic Engineering
a. Allows scientists to extract single genes from one species and
transfer it to another
b. It is more precise than selective breeding because the gene that
carries the desired trait is specifically targeted
c. Can be used to produce crops that are intended for certain
conditions such as salty soils, or reduced water availability
Risks of Genetic Engineering
a. Requires complicated techniques and equipment
b. There is a possibility that selected traits might move from a
genetically modified population into a natural population
c. The added genes could have unknown ill effects on the
environment, people or other organisms
7. DNA technology has many applications.
DNA technology can be used to make foods more nutritious, produce
better drugs for treating diseases, or screen for genetic disorders.
DNA profiles, or fingerprints, are now being used to solve crimes.
These profiles are unique and are based on about ten regions of DNA
known to vary among individuals.
Scientists studying genomes have been working toward sequencing all
the nucleotide pairs in human DNA and have identified about 30,000
genes within the human genome.
Cloning is a technology that makes copies of DNA. It has been used
to produce drugs to fight disease, as well as to affect the birth of
animals that are genetically identical to each other.
Questions to think about:
1. Who are/were James Watson and Francis Crick and how did they impact
They are/were Scientists that made the first accurate model of DNA.
2. Describe the shape of a DNA molecule and how nucleotide bases fit into
DNA is a double spiral strand. The strands are held together by
specific pairs of nucleotides.
3. What is a mutation?
Any change to the DNA of a cell.
4. What are the four bases in a DNA molecule and which ones fit together?
Adenine and Thymine
Cytosine and Guanine
5. What is a genetically modified organism?
An organism that has had a gene from another species transferred to
6. What is the difference between selective breeding and genetic
Selective Breeding – selecting parent organisms to pass their traits on to
Genetic Engineering- isolating specific DNA, inserting it into another
7. What are genes made up of?
8. What is the genetic code?
A sequence of bases in a strand of DNA
9. What is a genome?
All of the genetic material found within an organism.
10. What happens during replication?
DNA is copied
11. What does a pedigree show?
How genes are passed down from two or more generations.
12. What information does a DNA molecule carry?
DNA carries instructions for making proteins.
13. What are the names of the four bases in a DNA molecule and
which ones fit together?
14. What information does a DNA molecule carry?
The genetic material found in all living cells that contains the
information needed for an organism to grow, maintain itself and
15. What does DNA stand for? Spelling counts.
16. Describe the shape of a DNA molecule and how bases fit into
that structure. Draw a picture to illustrate this.
A twisted ladder
Sugars and phosphates on outside of double helix
Bases in the middle (rungs) AdenineThymine, Cytosine
Sugars connect to bases on outside
Phosphates separate the sugars
17. Who are the only people with the exact same genes?
18. What information is contained in DNA?
The genetic material found in all living cells that contains the
information needed for an organism to grow, maintain itself
19. Where can genes be found?
In a chromosome on a strand of DNA
20. What is DNA made of?
Sugars, Phosphates and nitrogen bases
21. The outside of a DNA double helix is made up of what 2
Sugars and Phosphates
22. A protein is made of _____ consecutive bases. What is an
example of this?
23. If you were given the letters,
24. What are 4 combinations (or proteins) that could be made?
AGT, GTT, TTG, TGC
25. What makes up the parts of a DNA molecule (rungs and
Sides sugars and phosphates
Rungs Nitrogen bases
26. Replication takes place during which phase of the cell cycle?
27. Why is replication important?
To ensure that each new daughter cell has the correct genetic
information to carry on all life activities.
Part 4Fill in the Blank:
1. Genetic Code: Scientists describe DNA as containing a code. A code is
a set of rules and symbols used to carry information.
2. Over the years, horses have become faster, corn has become sweeter,
and pigs have become leaner. These are all examples of Selective
3. A genetic disorder or disease is an example of a mutation.
4. Replication: The process by which DNA is copied before it condenses
5. Making plants more insect resistant is due to Genetic Engineering.
6. Dolly the sheep is an example of Cloning.
7. Deoxyribonucleic Acid: The genetic material found in all living cells
that contains the information needed for an organism to grow, maintain
itself and reproduce.
8. A family tree is an example of a Pedigree.
9. RNA: A molecule that carries genetic information from DNA to a
ribosome, where the genetic information is used to bring together amino
acids to form a protein.
10. Gene: The basic unit of heredity that consists of a segment of DNA on
11. Proteins are made up of Amino Acids. Your body gets Amino Acids
from protein in food such as meat, eggs, cheese and some beans. After
taking in Amino Acids your body can use them to build proteins needed
for proper cell functioning. There are in fact 20 different Amino Acids. *
* The same vocab word is used throughout this sentence.
12. A double helix can be described as a Twisted Ladder.
3. http://www.pbs.org/ wgbh/ nova/ photo51/ jour-flash.html