Title: Chapter 10: DNA
1Chapter 10 DNA
- Something to think about
- Look around the room at your classmates. Observe
how they vary in the shape of their front
hair-line, the space between their front teeth,
the way in which their earlobes are attached to
their head. - Could these traits be inherited?
- How are traits passed from generation to
generation?
2The Central Dogma of Molecular Biology
- Genes code ? enzymes ? perform functions in the
cell that results in a phenotype - DNA ? RNA ? Protein
Transcription
Translation
310.1 Experiments showed that DNA is the genetic
material
- Biologists had to find out the chemical nature of
genes. - Griffith Transformation
- Factors in heat-treated harmful bacteria can be
transmitted to harmless bacteria that dont cause
disease - Hershey-Chase
- Offered supporting evidence that genes are
composed of DNA - Showed that radioactive tagged DNA entered
bacterial cells but radioactive tagged protein
did not. Therefore genetic information is located
in the DNA
4DNA and RNA are polymers ofNucleotides
- DNA Deoxyribonucleic Acid
- Found in the nucleus
- Three subunits
- Deoxyribose (5 carbon sugar)
- Phosphate
- Nitrogen Base (can be 1 of 4)
- Guanine
- Cytosine
- Adenine
- Thymine
5G pairs with C T pairs with A
Sugar-Phosphate Backbone
Nitrogenous Bases
6Purines and Pyrimidines
Purines Have two rings
Adenine Guanine
Pyrimidines Have one ring
Thymine Cytosine
7DNA is a double-stranded helix
- Chargaffs Rules
- Determined that the percent of guanine (G) and
cytosine (C) are nearly equal in any sample of
DNA the same was so for thymine (T) and adenine
(A). - X-Ray Evidence
- Rosalind Franklin took X-ray images of the DNA
molecule that helped to develop the model for DNA - The Double Helix
- Francis Crick and James Watson developed the
double helix model of DNA
8DNA is a double-stranded helix
- A double helix looks like a spiral staircase.
- Hydrogen bonds hold the two strands of DNA
together - The As on one strand hydrogen bond to the Ts on
the other, likewise for Gs and Cs - Base pairing explains why the percentage As is
the same as the percentage of Ts
9The shape of DNA is important because
- Our DNA makes up 1 of our body weight, so a 150
lb. person would have 1.5 lbs. of DNA. - In one cell 3 meters of DNA.
- If you typed out your entire DNA sequence in
Times 12pt font you would fill enough paper to
reach the top of the Washington Monument in D.C.
10DNA Replication
Video
- It has not escaped our notice that the specific
pairing we have postulated immediately suggests a
possible copying mechanism for the genetic
material Watson and Crick - The semi conservative model when a double helix
replicates, each of the two daughter molecules
will have one old strand (parental or template)
and one new strand.
11DNA Replication
Video
- Step 1 Double helix unzips
- Replication begins at origins of replication
- Helicase unzipping enzyme
- H-bonds break
- Replication fork the point at which the two
strands split - Step 2 Each original strand becomes a template
strand (white) - Complementary bases fill in from the 5 end to
the 3 end (opposite directions) - DNA polymerase building enzyme adds new bases
- Step 3 Proofreading by DNA polymerase
12DNA Replication
Enzyme (Helicase) Unzips
T A A G C
A T T C G
T A A G C
New Strands
T A A G C
Enzyme (DNA Polymerase) fills in new nucleotide
bases
13The molecular basis for traits
- An organisms genotype is its genetic make-up
- A phenotype is the organisms specific trait.
- For example the gene OCA2 causes the albino
phenotype - The DNA specifies traits by providing the
instructions on how to make protein.
14The Chain of Command In the Cell
- DNA ? RNA ? Protein
- Genes code ? enzymes ? perform functions in the
cell that results in a phenotype
Transcription
Translation
15The one gene one enzyme hypothesis
- Beadle and Tatum determined that mutant mold
strains were defective in a single gene for each
type of mutant - Their hypothesis that there is one gene for every
enzyme was correct except it wasnt just for
enzymes it was discovered that there is one gene
for every protein. Further, scientists discovered
that there are some proteins made of several
polypeptides so again they changed the hypothesis
to one gene one polypeptide.
16RNA Structure
- RNA Ribonucleic Acid
- Single stranded!
- Can leave the nucleus
- Monomers made of
- Ribose (5 carbon sugar)
- Phosphate
- Nitrogen Base (1 of 4)
- Guanine
- Cytosine
- Adenine
- Uracil (Instead of Thymine)
17Three Kinds of RNA
- Messenger RNA (mRNA)
- conveys genetic information from the DNA in the
nucleus to the rest of the cell - Ribosomal RNA (rRNA)
- structural, part of ribosome
- Transfer RNA (tRNA)
- carries amino acids to site of protein synthesis,
it is a material transporter (not for information)
18Genetic information written in codons is
translated into amino acid sequences
- RNA is a complementary copy of a DNA template
strand instead of As pairing with Ts such as
in DNA replication, the As in DNA pair with Us
in RNA. - The mRNA is then decoded into protein through a
process called translation. - Codons are groups of three nucleotide bases
- Each codon on mRNA codes for a specific amino
acid.
19Transcription and Translation of Codons
20Transcription
- RNA polymerase creates the RNA sequence from the
template DNA in the nucleus - Three Stages
- Initiation RNA polymerase begins at the
promoter sequence - Elongation RNA strand peals away from the DNA
template - Termination RNA polymerase reaches the
terminator sequence and detaches from the DNA
Animation
21Transcription
DNA rezips
Enzyme (Helicase) Unzips
RNA Leaves to go to a ribosome
T A A G C
RNA Strand
U A A G C
Enzyme (RNA Polymerase) fills in new nucleotide
bases
Template Strand
22CTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTCTGAAAGTGGAC
CTATCAGCAGGATGTGGGTGGGAGCAGATTAGAGAATAAAAGCAGACTGC
CTGAGCCAGCAGTGGCAACCCAATGGGGTCCCTTTCCATACTGTGGAAGC
TTCGTTCTTTCACTCTTTGCAATAAATCTTGCTATTGCTCACTCTTTGGG
TCCACACTGCCTTTATGAGCTGTGACACTCACCGCAAAGGTCTGCAGCTT
CACTCCTGAGCCAGTGAGACCACAACCCCACCAGAAAGAAGAAACTCAGA
ACACATCTGAACATCAGAAGAAACAAACTCCGGACGCGCCACCTTTAAGA
ACTGTAACACTCACCGCGAGGTTCCGCGTCTTCATTCTTGAAGTCAGTGA
ACCAAGAACCCACCAATTCCAGACACACTAGGACCCTGAGACAACCCCTA
GAAGAGCACCTGGTTGATAACCCAGTTCCCATCTGGGATTTAGGGGACCT
GGACAGCCCGGAAAATGAGCTCCTCATCTCTAACCCAGTTCCCCTGTGGG
GATTTAGGGGACCAGGGACAGCCCGTTGCATGAGCCCCTGGACTCTAACC
CAGTTCCCTTCTGGAATTTAGGGGCCCTGGGACAGCCCTGTACATGAGCT
CCTGGTCTGTAACACATTCCCCTGTGGGGATTTAGGGACTTGGGCCTTCT
GTCTTTGGGATCTACTCTCTATGGGCCACACAGATATGTCTTCCAACTTC
CCTACACAGGGGGGACTTCAAAGAGTGCCTTGAGCTGATCTGGTGATTGC
TTTTTTGTACTGTTATTTATCTTATTCTTTTCATTGTGAGGTACTGATGC
AAACACTTTGTACGAAAAGGTCTTTCTCATCTCGGGAGTCCCCGTCTATT
TGTCCCGGTCCCTGTTAACCCAGTCCCCGACAGGAGCCCCTTCTGCACCT
TGAGCTCTCACCACTCACCGTCCATCCAGCCCCAGCTCTGCCTGCAACCC
ACCCATCCCTGGGACTCGGGCCTCCCCTCTCTAGTGGTCTGGTCATCAGG
CCAGGGGCACGTGGAAGAAGCTATCGTGGCAAAGGGAGCAGTCATATCCC
CAAAATCTGTGGTTGGTTTACCACCACCATGGAAACCCCAGGGTGGGACT
CTAGTTTCAGGTTGGAGCTGAGCCCTGTCGGGAATGAGCTTTCCCCAGCT
ATGGCTTCTTGGGGCCCCTGTGCCCTGAGCTGTGTCTCCCAGCATCGGGT
CCCCACCATGCATATGGCCCACTCAGGCACAGTGCCGCGATGGCTGCATG
CGTGAGGGGGGCCTGGGCCCAGGGCTGGGAGTCCTTTGTGTCTCATGGCC
ATGATTGTCCTTCCGAGTATGATATGGTGGCCAATTTCTTTTATTCTGTC
GTTCAGAGTGAGTAAATGATGTAGAGTTCATGCAGAAAAAAATACAACAA
AAACCAAGGGAACATAGAATTGGAAAACGCGTCACAGCAATGAGTTAAAT
AGGTAACAAATTTCATCATTTGAAGAAAGACTTAGAGTGCCAAAAGTGCC
TCTTAAGTCTCCTTTAAAAAGTAGCAAAATTCATCCCTGAAGAAGCATCT
TGGCCTTTTTCATGTACTCAGAGTGCTGGTGAAGAACAAAGATTGCTGAA
ACATTATGTACCTAACAGCGTTACAGGGTGTAGATAACACACTGGAAAAC
CTGGTCGTTACAGTGGACATATTCCAGGAAGTCCTTGCCTGAGGTTTTCC
AAGTTATGGAATTGCTTGAGATTGGAAGAGGCGATGGAGGGTACAACTGT
AATGCCCAACCTCATTTTTGCTAACCCTGTTTTTAGACTCTCCCTTTCCT
TCAATCACCTAGCCTTCTTTCCACCTGAAAGGACTCTCCCTTAACTGAGA
GAACCGGACAGACTCCATCTTGGCTCTTTCACTGGCAGCCCCTTCCTCAA
AGACTTAACTCGTGCAAGCTGACTCCCAGGACATCCGAGAATGCAATTAA
CTGACAACCTACTGTGGCGAGCTACATCCGCAGTCCCCAGGAATTCGTCC
GATTGATAACGCCCAATTACCCGCGTCTATCACCTTGTAATAGTCTTAAA
GCACCTGCACCTGGAACTGTTTACTTTCCTGTAACCATTTATCCTTTTAA
CATTTTGCCTGATTTACTTATGTAAAATTCTTTTAACTAGACCGCCACTC
CCCTTTCTAAACAAAAGTATAAAAGAAAATCTAGCCCCTTCTTTGGGACT
GAGACAATTTTGAGGTTAACGCAGGGTGCCTGTAATCCTAAGGGAGGAGA
CCGCCACTTCTGCTGCCCTTCCCTTCCCCACACCCCCTTCTCTAGTTTAT
GAAACAGGGAAAAAGGGAGAAAGCAAAAAGATAAAAAAAACAGAAGTAAG
ATAAATAGCTAGACGACCTTGGCAGCACCACCCGGCACTGGTGGTTAAAA
TAATAATAATAATAATATTAACCCCTGACCTAAACTACTTGTGTTATCTG
TAAATTCCAGACACTGTATGAGGAAGCCCTGCAAAACTTTCTGTTCTGTT
ATCTGATGCGTGTAGCCCCCAGTCACGTTCCGATGCTTGCTCGATCTATC
ACGACCCTTTCAAGTGAACCCCTTAGAGTCGTAAACCCTTAAAAGGGCCA
GGAATTTCGTTTTCGGGGAGCTCGGCTCTTCAGGCCCAAGTAAACCTGCC
GTATCTCACCTGAGACCAACCCCCAACTACAAAACTCAACCTGGAATTTT
CCCAGGACCAAACCCATCTATATTCTGTAACCCGAAACCTCAAAGCCTAA
CCCTAACCCTAACCCCTACAGTTGAGGTCCCCCCGCCCCTGTGGTTCCAG
CTCAAGACAACCTGCCCCTCCGTGGGTTTGCAGGCCCTCTGGTGGGGGTG
GGAGCTGGGGGCCACATACAGCTCTCTGAGCTTAAGCCATTTTCTTCCTT
CATTCCTTCCTTCCTCCCTCCCTTCCCTTCCTTCCTCCCTCCCTCCCTCC
TTCCCTCCCTCCCTTTTTTTTTTCAGGGTCTTGCTCTGTCACCCAGGCTG
GAGTGCAGTGGCATGATCACAGCTGACTGCAGCCTCGGACTCCCAGGCTC
AAGTTATCTTCCCTCCTCAGCCTCCAGAGTAGGTGGGACTACAGGAGTGT
GCCATCGCACCCAGCGAATTTCTTAATTTTTATTTTGTAGAGATGAGGCC
TCTCGATATTGTCCAGGCTTGGAAGTAGTTCTTGAAATTCAAGAGGATCT
TGAAGTTCTGACCTCCTGTCAATATCCCTTCCCCTCACCTTGACCCTCCC
ATTCTGCCCCACCTGTCAGGATCACAAGGACCCCCAGATCAGCAGATGGG
AACCGGACCAAAAAGAGAAATAGTGCTGTCCCGCCCATAAGTACCACCCC
CAGACTCCCTGCTCCACCCTCTGGACCACAGGGAGGCCCCATGCTCCATC
CCTGAAAACCACCCCCAGACCCCCTGCTCCTCCCCACGGGACCGCCCCCA
GATCCACTGTTCCTGTCCTCCGGACCACACCGGACAGCTCCTTCCCTCGG
CGCCATCCCCAGACCCCAGCTCCTCCCCTCAGGATCATCCCCAGACCCCC
GCTCCTCCCATCAGGACCGCCCCCAGAACCCCCTGCTCCTCCCCACAGGA
CCACCCCCAGACCCCCGCTCCTCCCCTAAGGACCACCCACAGACCCCCAC
GCTTCCCCTCGGGACCACCCCCAGACCCCCGCTCCTCCCCTCAGGACCAC
CCCCAGATCCACTGTTCCTGTCCTCCGGACCACACCAGACAGCTCCTTCC
CTCGGCGCCATCCCCAGACCCCCACGCTTCCCCTCGGGACCACCCCCAGA
CCCCCGCTCCTGCCCTCGGGACCACGCCCAGACCCCCTGCTCCTCCCCAC
GAAACCACGCCCAGTAACCCCCCTCTTCTCCCCTCAGGACCACCCCCAGA
CCCCCGCTCCTCCCCTGGGAACCACCCCCAGACCCCCTGCTCCTCCCCAC
GAAACCACCCCCAGACTCCCTGCTCCTGTCCTCCGGACCACGCGACTGCT
CCTTCCCTCAGCGCCACCCCCAGACTGCCGCTCCTCCTGTCGGGACCCCC
TGAGGCTTTCTCCACCCGGAGTGCGGGGTAGGGAGCAGACGGAGAGTGAC
GGAGGGTGACGGAGAGTGACGAAAGTAGACGATGTCTGACGGAGAAGAGC
CGAGCGGAGCTGAAGGGCGGCGGAGAGTGACGGAAAGTGGCGAGAATTGA
CGGAAAGTGACGGGGACTGACGGACAGTGACGAAGAGTCACGAAATTTAT
CAGAGGGCGACAAAGAGGAAAGCGAAATGGTGAGATGCAGCCGGCCGAGC
CTAATCGGAGATGACGGAAAGTGACGGAGAGGAACGAGGAGTAAAGAGGG
GTGACGAAAAGAGCCGAAGCTGGTGGAGGCGAAGAACTGAGTGAGGGAAG
ATAGCCGAGATTAGCGGGTGGGCTGCAGCCGGGGCAGTCGCCCGAATGGG
CGGGACCCCACGGAGTTAGCGAGAGGATGCGAACAGCGGCCAGCCGGGCA
GCACGCGAGCGAGGGAGGGCGTGGAGGGCCGTGGGTCCGCCTGCACTGAG
GCAGGCATGCGTGGCACCGAGGTGACCCGGGTGGGAGGTGCACCGCCGCC
CCCTGGCAGTCTCTCCGCGGAGCCCAAGCCCGTCTTCTCCGCCCCTTTGC
AGACCTCGGCGCCCAGCCTGGCCCCTGACGCCCACCCGCGGCCCCACCCA
GCGCCCGGGCCCACGAGGCCGAGGAGCGGCGGAGACTAACGGCCCCTGGA
CCCCAGGCAGCACATGGCCCAGAGCATCCCAGCCCAGTGGAGGGCGGCAC
ATGGCGGGAGGGCGGGAGTCCGTGTCCACTCATGGCCGGGGAGGGGAGGG
CAAGTTCTGGTGGCTGGGGAGGCCTAGAGCATCACAGCCCAGTGGAGGGC
TGCACATGGCAGGGGAGGGGAGAGCAAGAGTGTGCGGGCGAGGGAGGAGA
GGGCAAGACTGCGTGTCCGCTCCAGTCTCTCTTCCTCATCTTATAAAGCC
ACGAGTCCCATGACTGGGGACCCAACCTAATAACATTATCTAATCCTAAT
TGCCTCCCAAAGGCCATATCTCCAATCAGGACATGAATTCGGGGATTAAA
TTGCCAACACATGGCTGGGCGCGATGGCTTGTGCTTTTTTTTTTTTTTTT
TTTGAGACGGAGTCTCGCTCTGTCGCCCAGGCTGGAGTGCAGTGGCGCTA
TCTCGGCTCACTGCAAGCTCTGCCTCCCGGGTTCACGCCATTCTCCTGCC
TCAGCCTCCTGAGTAGCTGGGACTACAGGCGCCCGCCACCACGCCCAGGT
AATTTTTTTTTTTTTTTTTTTGTATTTCTTTGTAGAGACGGGGTTTCACC
ATGTTAGCCAGGATGGTCTCGATCTCCTGACCTCGTGATCCACCCATCTC
GGTCTCCCAAAGTGCTAGGATTGCAGGCCTGAGCCACCGCACCCAGCTGC
CTTGTGCTTTTAATCCCAGCACTTTCAGAGGCCAAGGCAGGCGATCACCT
GAGGTCAGGAGTTCAAGACCAGCCTGGCCAACATGGTGAAACCCCATCTC
TAATACAAATACAAAAAAAAAACAAAAAACGTTAGCCAGGAATGAGGCCC
GGTGCTTGTAATCCTAAGGAAGGAGACCACCACTCCTCCTGCTGCCCTTC
CCTTCCCCACACCGCTTCCTTAGTTTATAAAACAGGGAAAAAGGGAGAAA
GCAAAAAGCTTAAAAAAAAAAAAAAAAAAACAGAAGTAAGATAAATAGCT
AGATGATCTTGGCAGCACCACCCGACCCTGGTGGTTAAAATAATAATAAT
AATAATATTAACCCCTGACCTAAACTACTTGTGTTATCTGTAAATTCCAG
ACACTGTATGAGGAAGCCCTGCAAAACTTTCTGTTCTGTTATCTGATGCG
TGTAGCCCCCAGTCACGTTCCCCATGCTTCCTCGATCTATCACAACCCTT
TCACGTAAACCCCTTAGAGTTGTAAACCCTTAAAAGGGCCAGGAATTTCG
TTTTCGGGGAGCTTGGCTCTTCAGGCGCAAGTGTGCCGATGCTCCTGGCA
GAGTAAAGCCCTTCCTTCTTTAACCCAGTGTCTGAGGAATTTTGTCTGCG
GCTTGTCCTGCCACAATGCCAGCTACCAGGAGGCTGAGGTGTGAGAATCG
CTCGAACCTGGGAGGCAGAGGTTGCAGCGAGCCGAGATCCCACGATTGCA
CTCCAGCCTGGGTGATAG
This DNA sequence will make a protein, however
not all of it will. Some of it is nonsense and
some of it gives information about when the
protein should be made where it should be sent,
etc.
23Post Transcriptional RNA Modification
- mRNA is edited before it makes protein
- Introns (garbage)
- Exons (the expressed genes)
- mRNA also sometimes gets caps and tails before
leaving the nucleus - Protect the RNA
- Help it bind to a ribosome
24The Genetic Code
- Within the DNA is a code to make proteins
- The genetic code is the set of rules that
determines which codon codes for each amino acid - Redundancy but no Ambiguity
- Start codon AUG
- Find the stop codons
25(No Transcript)
26A Proteins Shape Determines its Function
- Most enzymes are globular with a place the shape
of the substrate where the substrate binds
(active site). - Structural proteins (hair and tendons) are long
and thin.
27A Proteins Shape Depends on Four Levels of
Structure
- Primary Structure the sequence of amino acids
- Secondary Structure the protein folds into
local patterns. - Alpha helix
- Beta sheet
- Tertiary Structure the overall,
three-dimensional shape of the protein. - Quaternary Structure the combination of peptide
chains (sub-units) that form the entire protein.
28(No Transcript)
29Translation
Firefly Movie
- Ribosomes read mRNA and assemble polypeptides
- mRNA is the message that comes directly from DNA
(pink) - tRNA brings amino acids and matches them with the
correct codon on mRNA (green) - tRNAs anti-codon is complementary to the mRNAs
codon - tRNA enters the ribosome and drops off an amino
acid (purple) - Amino acid binds with the growing polypeptide
30Translation
- Initiation Translation begins at an AUG (start
codon) the tRNA binds with the anti-codon UAC - Elongation Amino acids are added to the
polypeptide chain until a stop codon is read - Peptide bonds are formed between each pair of
amino acids - Termination a stop codon is read by a tRNA
carring no amino acid
31Translation
Translation Animation
32Gene Regulation
- Not all genes are expressed in every cell
- Not all genes are expressed at the same time.
- An operon is a group of genes that operate
together - A skin cell expresses different genes than a
nerve cell
33Gene Regulation
34Mutations change the meaning of genes
- A mutation is any change in the nucleotide
sequence - Two types
- Point mutations when one base is substituted
for another - Frameshift mutations when a base is added or
deleted (the entire reading frame is changed)
35- Point mutations (Substitutions)
- Original The fat cat ate the wee rat.
- Point Mutation The fat hat ate the wee rat.
- Frameshift mutations (Insertion, Deletion)
- Original The fat cat ate the wee rat.
- Frame Shift The fat caa tet hew eer at.
Deletion
Substitution
Insertion
36What causes mutations?
- Spontaneous mistake (natural)
- Mutagens a physical or chemical agent
- Physical
- Radiation
- Chemical
- Nicotine
- Agent-Orange
- Benzene
- Bromine
37What do mutations cause?
- Diversity!
- Genetic Disease
- Sickle cell anemia
- Cystic fibrosis
- Huntingtons disease
- Cancer