DNA Its not just for college anymore

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DNAIts not just for college anymore!
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Web Sites

• DNA structure and replication animation
• Overview of gene expression
• DNA Models Translation model

http//207.207.4.198/pub/flash/24/menu.swf
http//www.genomicseducation.ca/animations/gene_ex
pression.asp
http//www.indigo.com/models/dna-models.html
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Learning Goals for DNA Genetics

• Know structure/function of DNA
• Know DNA is genetic material
• Illustrate how DNA specifies traits
• Understand mutations are change in DNA sequence
• Understand relationship between mutations in DNA
  and expressed phenotype

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What Is DNA

• Deoxyribonucleic acid
• Everyone knows this?
• Molecule of heredity
• Constitutes our genes
• Genes are stretches of DNA sequence
• DNA is present in each cell
• Passed on to gametes and into progeny

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What is DNA, Really

• Polymer of nucleotides
• Polymer? Nucleotides?
• Polymer
• A large molecule that is a series of joined
  smaller molecules
• Nucleotides
• The small molecules that make up the large DNA
  polymer

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DNA Concepts

• Genes
• Chromosomes
• Complementary base-paired double helix
• Polymer of nucleotides
• The sequence of nucleotides is the information of
  DNA

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DNA Concepts

• DNA controls traits of organism
• Traits pass from parent to offspring
• DNA is copied during cell division
• DNA is present in sex cells
• DNA is passed from parent to offspring

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Why are DNA Concepts Difficult?

• Chemical names?
• Deoxyadenosine, purine, pyrimidine
• Chemical processes?
• base pairing, hydrogen bonds
• Genetic principles?
• DNA replication
• Mutations
• Chromosome segregation assortment

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Why is DNA So Difficult?

• Chemical Names
• Deoxyadenosine monophosphate
• Pyrimidine
• Persons Names
• Martina Navratilova
• Hakeem Olajuwon

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How About Pictures Names
C
B
A

• __ Hakeem Olajuwon
• __ Purine
• __ Kareem Abdul-Jabbar
• __ Deoxyadenosine monophosphate
• __ Pyrimidine
• __ Martina Navratilova
• __ Deoxycytidine monophosphate
• __ Nadia Comaneci

E
F
C
H
E
B
D
G
D
A
F
G
H
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NucleotidesThe building blocks of DNA
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Nucleotide Structure
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Nucleotides
Adenosine monophosphate Cytidine
monophosphate Guanosine monophosphate Uridine
monophosphate
Deoxyadenosine monophosphate Deoxycytidine
monophosphate Deoxyguanosine monophosphate Deoxyth
ymidine monophosphate
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Nucleotide Polymerization Reaction
Phosphodiester Bond Formation
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Order of Nucleotides

• As nucleotides join the strand they generate a
  sequence
• Inherent fidelity of DNA replication

TAAGTGTACACGTA
TAAGTGTACACGTA
ATTCACATGTGCAT
TCACATCG
TAAGTGTACACGTA
TCACATCG
TCACATCG
TAAGTGTACACGTA
TCACATCG
AGTCCGATCGTAACTGGG


ATTCACATGTGCAT
AGTGTAGC
TCAGGCTAGCATTGACCC
AGTGTAGC
AGTGTAGC
ATTCACATGTGCAT
TAAGTGTACACGTA
ATTCACATGTGCAT
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DNA Sequence

• Human Genome Project
• sequencing the human genome
• What does sequencing mean?
• To determine the order of the nucleotides in the
  human DNA molecules
• Human DNA molecules are our chromosomes
• Each chromosome is a DNA double helix
• Each DNA double helix is two single DNA molecules
  intertwined
• Each single DNA molecule is a chain of nucleotide
  units
• Sequencing is the method to determine what the
  exact order of units is in this chain

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Gene Expression
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A Gene is a Transcription Unit
Promoter Regulatory sequences
Terminator
Coding sequences
DNA
Transcription
mRNA 5
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Open reading frame
Start codon
Stop codon
Ribosome binding site
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Transcription
Coding
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Overview of gene expression
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Translation
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Translation Elongation
aa-tRNA entry
Peptidyl transferase
Termination
Translocation
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Translation
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The code is 3 letter words, but what about
punctuation?
GROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW

• Code written in three letter words - codons
• Ribosomes must start at the right place to read
  the message
• There are three frames, but only one is read to
  give an intelligible message
• Need a start codon (NOW) and a stop codon (END)
  to define the frame to use
• frame b
• NOW THE CAT SAW THE DOG BUT DID NOT RUN

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Reading Frames Mutation Types

• Frame shift mutations
• Original reading frame is frame a
• Insertions or deletions shift the reading frame

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Reading Frames Mutations
ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW
a b c

• Once a ribosome begins translation in a
  particular frame (a) it does not shift frames
• Therefore, if a mutation shifts the reading frame
  in the mRNA, the ribosome will read the wrong
  frame.

NOW THE CAT SAW THE ADO GBU TDI DNO TRU NEN DSE
W..
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Reading Frames Mutations
ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW
a

• A change that creates a stop codon is a
  non-sense mutation
• Generates a truncated protein

NOW THE CAT SAW THE DOG BUT END
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Reading Frames Mutations
ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW
a

• A change that creates a different codon is a
  mis-sense mutation
• Generates a protein with an altered sequence

NOW THE CAT SAW THE HOG BUT DID NOT RUN END
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Molecular Basis of Phenotype
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Effect of Mutations

• Sickle cell disease
• single nucleotide change A?T