DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material ...

21
DNA Structu re & Functio n Chapter 13

Transcript of DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material ...

Page 1: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

DNA Structure & Function

Chapter 13

Page 2: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

2DNA Structure DNA Structure & Function& Function

Mr. KarnsMr. Karns

Genetic MaterialGenetic Material

TransformationTransformation

DNA StructureDNA Structure

Watson and CrickWatson and Crick

DNA ReplicationDNA Replication

Prokaryotic versus EukaryoticProkaryotic versus Eukaryotic

Replication ErrorsReplication Errors

Page 3: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

3DNA Structure DNA Structure & Function& Function

Genetic MaterialGenetic Material

Frederick Griffith investigated virulence of Frederick Griffith investigated virulence of Streptococcus pneumoniaeStreptococcus pneumoniae

Concluded that virulence passed from the Concluded that virulence passed from the dead strain to the living straindead strain to the living strain

TransformationTransformation

Further research by Avery et alFurther research by Avery et al

Discovered that DNA is the transforming Discovered that DNA is the transforming substancesubstance

DNA from dead cell was being incorporated DNA from dead cell was being incorporated into genome of living cellsinto genome of living cells

Page 4: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

4Griffith’s Transformation Experiment

Page 5: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

5DNA Structure DNA Structure & Function& Function

Reproduction of VirusesReproduction of Viruses

Viruses consist of a protein coat (capsid) Viruses consist of a protein coat (capsid) surrounding a nucleic acid coresurrounding a nucleic acid core

Bacteriophages are viruses that infect Bacteriophages are viruses that infect bacteriabacteria

Hershey and Chase:Hershey and Chase:Radioactively labeled the DNA core and Radioactively labeled the DNA core and protein capsid of a phageprotein capsid of a phage

Results indicated that DNA, not the protein, Results indicated that DNA, not the protein, enters the hostenters the host

The DNA of the phage contains genetic The DNA of the phage contains genetic information for producing new phagesinformation for producing new phages

Page 6: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

6Bacteria and Bacteriophages

Page 7: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

7Hershey and Chase Experiments

Page 8: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

8DNA Structure DNA Structure & Function& Function

Structure of DNAStructure of DNA

DNA contains:DNA contains:

Two Nucleotides with purine basesTwo Nucleotides with purine bases

­ Adenine (A)Adenine (A)

­ Guanine (G)Guanine (G)

Two Nucleotides with pyrimidine basesTwo Nucleotides with pyrimidine bases

­ Thymine (T)Thymine (T)

­ Cytosine (C)Cytosine (C)

Page 9: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

9DNA Structure DNA Structure & Function& Function

Chargaff’s RulesChargaff’s Rules

The amounts of A, T, G, and C in DNA:The amounts of A, T, G, and C in DNA: Identical in identical twinsIdentical in identical twinsVaries between individuals of a speciesVaries between individuals of a speciesVaries more from species to speciesVaries more from species to species

In each species, there are equal amounts of:In each species, there are equal amounts of:A & TA & TG & CG & C

All this suggests DNA uses complementary All this suggests DNA uses complementary base pairing to store genetic infobase pairing to store genetic info

Human chromosome estimated to contain, on Human chromosome estimated to contain, on average, 140 million base pairsaverage, 140 million base pairs

Number of possible nucleotide sequences Number of possible nucleotide sequences 4,140,000,0004,140,000,000

Page 10: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

10Nucleotide Composition of DNA

Page 11: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

11DNA Structure DNA Structure & Function& Function

Watson and Crick ModelWatson and Crick Model

Watson and Crick, 1953Watson and Crick, 1953

Constructed a model of DNAConstructed a model of DNA

Double-helix model is similar to a twisted Double-helix model is similar to a twisted ladderladder

­ Sugar-phosphate backbones make up the sidesSugar-phosphate backbones make up the sides

­ Hydrogen-bonded bases make up the rungsHydrogen-bonded bases make up the rungs

Received a Nobel Prize in 1962Received a Nobel Prize in 1962

Page 12: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

12X-Ray Diffraction of DNA

Page 13: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

13Watson/Crick Model of DNA

Page 14: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

14DNA Structure DNA Structure & Function& FunctionReplication:Replication:

Prokaryotic vs. EukaryoticProkaryotic vs. Eukaryotic

Prokaryotic ReplicationProkaryotic Replication

Bacteria have a single circular loopBacteria have a single circular loop

Replication moves around the circular DNA Replication moves around the circular DNA molecule in both directionsmolecule in both directions

Produces two identical circlesProduces two identical circles

Cell divides between circles, as fast as every Cell divides between circles, as fast as every 20 minutes20 minutes

Page 15: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

15DNA Structure DNA Structure & Function& FunctionReplication:Replication:

Prokaryotic vs. EukaryoticProkaryotic vs. Eukaryotic

Eukaryotic ReplicationEukaryotic Replication DNA replication begins at numerous points along DNA replication begins at numerous points along

linear chromosomelinear chromosome DNA Unwinds and unzips into two strandsDNA Unwinds and unzips into two strands Each old strand of DNA serves as a template for a Each old strand of DNA serves as a template for a

new strandnew strand Complementary base-pairing forms new strand on Complementary base-pairing forms new strand on

each old strandeach old strand Replication bubbles spread bi-directionally until they Replication bubbles spread bi-directionally until they

meetmeet

Semiconservative:Semiconservative: One original strand is conserved in each daughter One original strand is conserved in each daughter

moleculemolecule

Page 16: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

16Semiconservative Replication

of DNA

Page 17: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

17Meselson and Stahl’sDNA replication experiment

Page 18: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

18Replication:Prokaryotic vs.

Eukaryotic

Page 19: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

19DNA Structure DNA Structure & Function& Function

Replication ErrorsReplication Errors

Genetic variations are the raw material for Genetic variations are the raw material for evolutionary changeevolutionary change

Mutation:Mutation:

A permanent (but unplanned) change in base-A permanent (but unplanned) change in base-pair sequencepair sequence

­ Some due to errors in DNA replicationSome due to errors in DNA replication

­ Others are due to to DNA damageOthers are due to to DNA damage

DNA repair enzymes are usually available to DNA repair enzymes are usually available to reverse most errorsreverse most errors

Page 20: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

20DNA Structure DNA Structure & Function& Function

ReviewReview

Genetic MaterialGenetic Material

TransformationTransformation

DNA StructureDNA Structure

Watson and CrickWatson and Crick

DNA ReplicationDNA Replication

Prokaryotic versus EukaryoticProkaryotic versus Eukaryotic

Replication ErrorsReplication Errors

Page 21: DNA Structure & Function Chapter 13. DNA Structure & Function 2 Mr. Karns Genetic Material  Transformation DNA Structure  Watson and Crick DNA Replication.

DNA Structure & Function

Ending Slide Chapter 13