DNA and RNA

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					     Homework for break

• Read Chapter 12 in textbook
• 2 Webquests
• Short Essay for second webquest typed.
             Homework
•   Read beginning of chapter 12; complete
    workbook section 12.1!

• Do Now:
1. How is meiosis different than mitosis?
2. What is the macromolecule involved in
   storing information (be careful!)?
3. What are the monomers of this
   polymer?
DNA and RNA

   Genetics
        Frederick Griffith 1928




Transformation - process in which one
strain of bacteria is changed by a gene or
genes from another strain of bacteria
               Do Now

• Homework: workbook 12.2 w/ associated
  reading; have workbook 12.1 out to
  check

1. What did Griffith’s and Avery’s
  experiments prove? Give a brief
  paragraph explaining the importance of
  their findings.
   Avery and other scientists discovered
        DNA is the Avery that stores
   thatOswaldnucleic acid1944
   and transmits the genetic information
   from one generation of an organism to
• World knows a molecule carries the
   the next.
 genetic information.

• Doesn’t know if the molecule is a:
  protein, lipid, carbohydrate, RNA, or DNA

• Avery performs Griffith’s experiment
  again with a twist.
Hershey-Chase Experiment
          1952
• Good scientists are naturally skeptical.

• Hershey-Chase are testing to see if DNA
  is the molecule that carries genetic
  information.

• Bacteriophage - virus that infects
  bacteria
                  Quiz

• Explain the importance of Griffith’s and
  Avery’s experiments in determining the
  molecule responsible for determining
  genetic inheritance…

• Homework: Section Assessment 1 and 2
  of chapter 12 (LL)
Hershey-Chase Experiment
            DNA Structure

• Nucleotide -
  monomer of
  nucleic acids
  made up of a 5-
  carbon sugar, a
  phosphate
  group, and a
  nitrogenous base
Sugar-Phosphate Backbone
   and Chargaff’s Rule

               • Simply states: If I
                 have a certain
                 number of
                 Cytosines I will
                 have about the
                 ______ number
                 of Guanines.
                 Same with A’s
                 and T’s.
      Rosalind Franklin 1950
        X-Ray Diffraction
• Clues from
  the X-Ray
  – Coiled
    (forming
    Helix)
  – Double-
    stranded
  – Nitrogeneous
    bases are in
    the center
          Watson & Crick

• Francis Crick – British physicist
• James Watson – American Biologist
  – Building a 3D model of DNA
  – Franklin’s X-Ray opened their eyes to the
    Double Helix
• Watson and Crick’s model of DNA was
  a double helix, in which two strands
  were wound around each other.
Double Helix
    Homework Study Guide
       12-1 and 12-2
1. List the conclusions and how each of these
   scientist got there:
  – Griffith
  – Avery
  – Hershey and Chase
2. How did Watson and Crick’s model explain
   why there are equal amounts of thymine and
   adenine in DNA?
3. Why did Hershey and Chase grow viruses in
   cultures that contained both radioactive
   phosphorus and radioactive sulfur? What
   might have happened if they only used one?
          Prokaryote DNA
• Prokaryotes
  – No Nucleus
  – Most have one circular chromosome located in
    the cytoplasm with some plasmids as well
  – E.Coli (1.6μm diameter)
  – 4,639,221 base pairs 1.6mm long
  – Like packing 300m of rope in your backpack
      Eukaryotes and DNA

• 1000 time more base pairs than bacterial
  DNA

• Smallest human chromosome has
  30million base pairs of DNA

• How do eukaryotes fit all that DNA in its
  nucleus?
    DNA to Chromosomes

• Vocab
  – Chromatin - granular material
    (uncondensed) within the nucleus; consists
    of DNA tightly coiled around proteins

  – Chromosomes – condensed chromatin

  – Histone - globular protein molecule around
    which DNA is tightly coiled in chromatin
         DNA Replication

• During DNA replication, the DNA
  molecule separates into two strands,
  then produces two new complementary
  strands following the rules of base
  pairing. Each strand of the double helix of
  DNA serves as a template, or model, for
  the new strand.
            Read 12-3

• Crossword Puzzle
1. Enzymes unwind
   DNA
2. Enzymes split
   “unzip” double helix
3. The enzyme, DNA
   polymerase, finds
   and attaches the
   corresponding N-
   base
4. Each “old” stand
   serves as a
   template and is
   matched up with a
   new stand of DNA
5. New helixes wind
   back up.
 DNA Replication


A–C–T–T–G–G–A–C
T–G–A–A–C–C–T-G
    Homework 12-3 Study
         Guide
• Quiz (5 min. – LL)
                 RNA
                   and
          Protein Synthesis




• Codon - three-nucleotide sequence on
  messenger RNA that codes for a single
  amino acid
• Anticodon - group of three bases on a
  tRNA molecule that are complementary
  to an mRNA codon
         Protein Synthesis
                  Two Main Parts

• Transcription             • Translation
  – Formation of a single     – Occurs on ribosomes
    strand of                 – Cell uses the
      messenger RNA             information on mRNA
    from DNA in the             to assemble amino
    nucleus                     acids in the proper
                                order to form specific
                                proteins
                Transcription
1. Occurs in nucleus
2. Enzymes unwind
   DNA
3. Enzymes split
   “unzip” double helix
4. RNA Polymerase
   binds to promoter
   sequence on DNA
5. RNA Polymerase
   transcribes a single
   strand of mRNA
           mRNA Editing
      before going to transcription


• Intron - intervening
  sequence of DNA;
  does not code for a
  protein (not used)

• Exon - expressed
  sequence of DNA;
  codes for a protein
  (used)
Translation
Translation
       Genes and Proteins

• Most genes only have instructions for
  assembling proteins.

• If that’s the case what do proteins have
  to do with eye color, hair color or height?
              Homework
•  Complete workbook section 12.3 and 12.4;
   study for quiz (E Day)
• Do Now:
1. Discuss DNA Replication. How is it related to
   RNA replication? List all the details you can
   in sequential order!
2. What happens when there are errors in
   “copying”? What are some of the ways we
   can fix this? What happens if we don’t?
               Mutations

• Mutation - change in a DNA sequence
  that affects genetic information
• Two Main Types:

  – Gene Mutation
    • Mutation that causes a change in a single gene


  – Chromosomal Mutation
    • Mutation that causes a change in an entire
      chromosome
                Gene Mutations
• Point Mutation
  (substitution)
   – mutation that affects a
     single nucleotide,
     usually by substituting
     one nucleotide for
     another


• Frameshift Mutation
  (insertion or deletion)
   – mutation that shifts
     the “reading” frame of
     the genetic message
     by inserting or
     deleting a nucleotide
  Chromosomal Mutations




• Chromosomal mutations involve
  changes in whole chromosomes.
Homework: Check site!
Gene Regulation
         Gene Regulation

• Prokaryote Gene Regulation
  – Will often have one OPERATOR (regulatory
    site) controlling the expression of more than
    one gene. OPERON
• Eukaryote Gene Regulation
  – Most eukaryotic genes are controlled
    individually and have regulatory sequences
    that are much more complex than those of
    the lac operon
        Gene Regulation
            Vocab
• Promoter - region of DNA that indicates
  to RNA polymerase where to bind to
  make RNA
• Operon - group of genes operating
  together
• Operator - region of chromosome within
  an operon to which the repressor binds
  when the operon is “turned off”
Lac Operon
  (E. coli)
• Operator bound –
  RNA polymerase
  can’t transcribe
  genetic
  information (not
  expressed)
• Operator free –
  gene(s) expressed
 Eukaryote Gene Regulation
Genes are regulated
in a variety of ways
                       DNA region about 30bp long
by enhancer
                       TATATAAA: help to align
sequences
                       RNA Polymerase
               Gene Reg. and
               Development
• hox genes - series of
  genes that controls
  the organs and tissues
  that develop in various
  parts of an embryo
• Mutations affecting the
  hox genes in the fruit
  fly, Drosophila, for
  example, can replace
  the fly’s antennae with
  a pair of legs growing
  right out of its head!
1.   What is meant by term base pairing? How is base
     pairing involved in DNA replication?
2.   When a DNA molecule is replicated, how do the new
     molecules relate to the original molecule?
3.   What is the difference between introns and exons?
4.   What is a codon? Anticodon? How do they relate?
5.   Explain why controlling proteins in an organism
     controls the organism’s traits.
6.   Name two major types of mutations. What do they
     have in common? How are they different? Give an
     example of each.
7.   The word transcribe means “to write out”, and the
     word translate means “to express in another
     language.” Review the meanings of transcription and
     translation in genetics. How do the technical
     meanings of these words relate to meanings of the
     words in ordinary language?

				
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posted:9/13/2012
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