Chapter 10 Notes

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Chapter 10 Notes

• DNA and RNA

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10-1 DNA- History

1. Freidrich Miescher (1868) found nuclear material
   to be ½ protein ½ unknown substance
2. 1890s, unknown nuclear substance named DNA
3. Walter Sutton (1902) discovered DNA in
   chromosomes
4. Fredrick Griffith (1928) working with
   Streptococcus pneumoniae conducted transformation
   experiments of virulent nonvirulent bacterial
   strains
5. Levene (1920s) determined 3 parts of a
   nucleotide
6. Hershey Chase (1952) used bacteriophages
   (viruses) to show that DNA, not protein, was the
   cells hereditary material
7. Rosalind Franklin (early 1950s) used x-rays to
   photograph DNA crystals
8. Erwin Chargaff (1950s) determined that the
   amount of AT and amount of CG in DNA called
   Chargaffs Rule
9. Watson Crick discovered double helix shape of
   DNA (A pairs with T C pairs with G) built the
   1st model

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10-1 DNA

• In 1928 Fredrick Griffith was studying the
  bacteria that cause pneumonia.
• - smooth ? mouse dies
• - rough ? mouse lives
• - heat killed smooth ? mouse lives
• - above rough ? mouse dies

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10-1 DNA
Heat-killed, disease-causing bacteria (smooth
colonies)
Harmless bacteria (rough colonies)
Control(no growth)
Harmless bacteria (rough colonies)
Heat-killed, disease-causing bacteria (smooth
colonies)
Disease-causing bacteria (smooth colonies)
Dies of pneumonia
Dies of pneumonia
Lives
Lives
Live, disease-causingbacteria (smooth colonies)
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10-1 DNA

• Griffith called this process transformation one
  type of bacteria turned into another
• ex. rough turns into smooth
• Avery and other scientists found that DNA is the
  nucleic acid that stores and transmits the
  genetic information from one generation to the
  next

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10-2 DNA

• The two categories of nitrogenous bases are
  purines and pyrimidines
• Purines double ring structure
• - adenine and guanine
• Pyrimidines single ring structure
• - cytosine and thymine

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10-2 DNA

• DNA is like a ladder
• - the rungs are made of the nitrogenous bases
• - the backbone is formed by the sugar and
  phosphate groups
• Chargaffs rule A T C G

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10-2 DNA
Purines
Pyrimidines
Adenine
Guanine
Cytosine
Thymine
Phosphate group
Deoxyribose
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10-2 DNA
Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key Adenine (A) Thymine (T) Cytosine (C) Guanine
(G)
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Section Quiz

• Avery and other scientists discovered that
• DNA is found in a protein coat.
• DNA stores and transmits genetic information from
  one generation to the next.
• transformation does not affect bacteria.
• proteins transmit genetic information from one
  generation to the next.

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Section Quiz

• DNA is a long molecule made of monomers called
• nucleotides.
• purines.
• pyrimidines.
• sugars.

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Section Quiz

• Chargaff's rules state that the number of guanine
  nucleotides must equal the number of
• cytosine nucleotides.
• adenine nucleotides.
• thymine nucleotides.
• thymine plus adenine nucleotides.

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Section Quiz

• In DNA, the following base pairs occur
• A with C, and G with T.
• A with T, and C with G.
• A with G, and C with T.
• A with T, and C with T.

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10-3 Chromosomes and DNA Replication

• Prokaryotes have a single strand of DNA that
  forms a circle
• - found in the cytoplasm
• The DNA of eukaryotes is linear and forms many
  strands
• - found in the nucleus

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10-3 Chromosomes and DNA Replication
Chromosome
E. Coli Bacterium
Bases on the Chromosomes
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10-3 Chromosomes and DNA Replication

• Eukaryotic DNA is tightly packed to form
  chromosomes
• - each chromosome contains both DNA and protein,
  packed together to form chromatin.
• - the DNA wraps around proteins called histones

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10-3 Chromosomes and DNA Replication
Nucleosome
Chromosome
DNA double helix
Coils
Supercoils
Histones
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10-3 Chromosomes and DNA Replication

• DNA Replication the copying of DNA before a cell
  divides
• DNA polymerase the enzyme used in replication

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10-3 Chromosomes and DNA Replication

• During DNA replication, the DNA separates into
  two strands, then produces two new complementary
  strands following the rules of base pairing.
  Each strand serves as a template for a new
  strand.
• DNA replication movie
• DNA replication movie 2

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10-3 Chromosomes and DNA Replication

1. Process by which DNA makes a copy of itself
2. Occurs during S phase of interphase before cell
   division
3. Extremely rapid and accurate (only 1 in a billion
   are incorrectly paired)
4. Requires many enzymes ATP (energy)
5. Begins at special sites along DNA called origins
   of replication where 2 strands open separate
   making  a replication fork

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10-3 Chromosomes and DNA Replication

•          Nucleotides added new strand forms at
  replication forks
•          DNA helicase (enzyme) uncoils breaks
  the weak hydrogen bonds between complementary
  bases (strands separate)
•           DNA polymerase adds new nucleotides to
  the exposed bases in the 5 to 3 direction
•           Leading strand (built toward
  replication fork) completed in one piece
•          Lagging strand (built moving away from
  the replication fork) is made in sections called
  Okazaki fragments

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10-3 Chromosomes and DNA Replication

•          DNA ligase helps join Okazaki segments
  together
•          DNA polymerase proofreads the new DNA
  checking for errors repairing them called
  excision repair

•   Helicase recoils the two, new identical DNA
  molecules

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10-3 Chromosomes and DNA Replication
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10-3 Chromosomes and DNA Replication
Original strand
DNA polymerase
New strand
Growth
DNA polymerase
Growth
Replication fork
Replication fork
New strand
Original strand
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Section Quiz

• In prokaryotic cells, DNA is found in the
• cytoplasm.
• nucleus.
• ribosome.
• cell membrane.

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Section Quiz

• The first step in DNA replication is
• producing two new strands.
• separating the strands.
• producing DNA polymerase.
• correctly pairing bases.

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Section Quiz

• A DNA molecule separates, and the sequence
  GCGAATTCG occurs in one strand. What is the base
  sequence on the other strand?
• GCGAATTCG
• CGCTTAAGC
• TATCCGGAT
• GATGGCCAG

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Section Quiz

• In addition to carrying out the replication of
  DNA, the enzyme DNA polymerase also functions to
• unzip the DNA molecule.
• regulate the time copying occurs in the cell
  cycle.
• proofread the new copies to minimize the number
  of mistakes.
• wrap the new strands onto histone proteins.

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10-4 RNA and Protein Synthesis

• RNA, like DNA, consists of long chains of
  nucleotides.
• Three differences between DNA and RNA
• - the sugar is ribose
• - single stranded
• - contains uracil instead of thymine
• base pairings are A-U and C-G

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10-4 RNA and Protein Synthesis
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10-4 RNA and Protein Synthesis

• Genes are coded DNA instructions that control the
  production of proteins.
• - each gene controls the production of a
  specific protein
• - DNA (gene) ? specific RNA sequence ? specific
  amino acid sequence

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10-4 RNA and Protein Synthesis

• There are three types of RNA
• 1. messenger RNA (mRNA)
• 2. ribosomal RNA (rRNA)
• 3. transfer RNA (tRNA)

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10-4 RNA and Protein Synthesis
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10-4 Messenger RNA (mRNA)

1. Single, uncoiled, straight strand of nucleic acid
2. Found in the nucleus cytoplasm
3. Copies DNAs instructions carries them to the
   ribosomes where proteins can be made
4. mRNAs base sequence is translated into the amino
   acid sequence of a protein
5. Three consecutive bases on mRNA called a codon
   (e.g. UAA, CGC, AGU)
6. Reusable

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10-4 RNA and Protein Synthesis
Ribosome
Ribosomal RNA
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10-4 Ribosomal RNA (rRNA)

• Globular shape
• Helps make up the structure of the ribosomes  
• Ribosomes are the site of translation (making
  polypeptides)
•  

• rRNA protein make up the large
• small subunits of ribosomes

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10-4 RNA and Protein Synthesis
Amino acid
Transfer RNA
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10-4 Transfer RNA (tRNA)

• Single stranded molecule containing 80
  nucleotides in the shape of a cloverleaf/hairpin
• - Carries amino acids in the cytoplasm to
  ribosomes for protein assembly
• Three bases on tRNA that are complementary
• to a codon on mRNA are called anticodons (e.g.
  codon- UUA anticodon- AAU)
• - Amino Acid attachment site
• across from anticodon site on tRNA
• -Enters a ribosome reads mRNA
• codons and links together correct
• sequence of amino acids to make
• a protein
• -Reusable  

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10-4 Transcription
Adenine (DNA and RNA) Cystosine (DNA and
RNA) Guanine(DNA and RNA) Thymine (DNA
only) Uracil (RNA only)
RNApolymerase
DNA
RNA
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10-4 Transcription

• Transcription the copying of the DNA into a
  complementary strand of RNA
• - uses the enzyme RNA polymerase
• During transcription, RNA polymerase binds to DNA
  and separates the DNA strands. RNA polymerase
  then uses one strand of DNA as a template from
  which nucleotides are assembled into a strand of
  RNA.
• The enzyme binds to the region DNA known as the
  promoter region.

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10-4 Transcription

• DNA helicase (enzyme) uncoils the DNA molecule
• RNA polymerase  (enzyme) binds to a region of DNA
  called the promoter which has the start codon AUG
  to code for the amino acid methionine
• Promoters mark the beginning of a DNA chain in
  prokaryotes, but mark the beginning of 1 to
  several related genes in eukaryotes
• The 2 DNA strands separate, but only one will
  serve as the template be copied
• Free nucleotides are joined to the template by
  RNA polymerase in the 5 to 3 direction to form
  the mRNA strand
• mRNA sequence is built until the enzyme reaches
  an area on DNA called the termination signal
• RNA polymerase breaks loose from DNA and the
  newly made mRNA
• Eukaryotic mRNA is modified (unneeded sections
  snipped out by enzymes rejoined) before leaving
  the nucleus through nuclear pores, but
  prokaryotic RNA is not

All 3 types of RNA called transcripts are
produced by this method
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10-4 RNA and Protein Synthesis

• RNA Editing
• Before it leaves the nucleus, RNA is edited.
  Splicing occurs by removing introns and fusing
  exons together.

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10-4 RNA and Protein Synthesis
Transcription Processing of Gene Information

• The Genetic Code
• The genetic code is read in three letter segments
  called codons.
• There are 64 different codon possibilities that
  code for only 20 amino acids
• -AUG is the start codon
• -there are 3 stop codons-
• UAA, UAG, UGA

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10-4 RNA and Protein Synthesis
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(No Transcript)
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10-4 Translation

• Translation the decoding of mRNA into an amino
  acid sequence
• During translation, the cell uses information
  from messenger RNA to produce proteins
• - anticodon the three letter sequence on tRNA
  that binds with mRNA

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10-4 Translation

• mRNA brings the copied DNA code from the nucleus
  to the cytoplasm
• mRNA attaches to one end of a ribosome called
  initiation
• tRNAs attach the correct amino acid floating in
  the cytoplasm to themselves
• tRNA with its attached amino acid has 2 binding
  sites where they join the ribosome
• The tRNA anticodon reads temporarily attaches
  to the mRNA codon in the ribosome
• Two amino acids at a time are linked together by
  peptide bonds to make polypeptide -chains
  (protein subunits) called elongation
• Ribosomes) move along the mRNA strand until they
  reach a stop codon (UAA, UGA, or UAG) called
  termination
• 8. tRNAs break loose from amino acid,
  leave the ribosome, return to
• cytoplasm to pick up another amino
  acid

Protein Synthesis Translation Animation
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10-4 Translation
Lysine
Phenylalanine
tRNA
Methionine
Ribosome
mRNA
Start codon
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10-4 Translation
Lysine
tRNA
Translation direction
mRNA
Ribosome
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10-4 Translation
Polypeptide
Ribosome
tRNA
mRNA
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Section Quiz

• The role of a master plan in a building is
  similar to the role of which molecule?
• messenger RNA
• DNA
• transfer RNA
• ribosomal RNA

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Section Quiz

• A base that is present in RNA but NOT in DNA is
• thymine.
• uracil.
• cytosine.
• adenine.

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Section Quiz

• The nucleic acid responsible for bringing
  individual amino acids to the ribosome is
• transfer RNA.
• DNA.
• messenger RNA.
• ribosomal RNA.

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Section Quiz

• A region of a DNA molecule that indicates to an
  enzyme where to bind to make RNA is the
• intron.
• exon.
• promoter.
• codon.