Chapter 16
Download
1 / 24

Chapter 16 - PowerPoint PPT Presentation


  • 152 Views
  • Uploaded on

Chapter 16. DNA & Replication. Bell Ringer. 1. On a sheet of paper 2. Write down everything you know about DNA -- Who discovered DNA? -- What is the structure of DNA? -- How does DNA differ from RNA? . The Beginnings.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Chapter 16' - saul


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Chapter 16

Chapter 16

DNA & Replication


Bell ringer
Bell Ringer

1. On a sheet of paper

2. Write down everything you know about DNA

-- Who discovered DNA?

-- What is the structure of DNA?

-- How does DNA differ from RNA?


The beginnings
The Beginnings

  • T. H. Morgan’s group showed that genes are located on chromosomes

    • The two components of chromosomes—DNA and protein— were candidates for the genetic material

  • The role of DNA in heredity was first discovered by studying bacteria and the viruses that infect them

  • The discovery of the genetic role of DNA began with research by Frederick Griffith in 1928


Griffin transformation
Griffin & Transformation

  • Griffin looked at bacteria & mice

  • Major finding = Transformation

  • Killed disease-causing bacteria + live, harmless bacteria

    • Result: Live, disease-causing bacteria

  • Transformation – change in genotype and phenotype due to uptake of foreign DNA


Mixture of heat-killed S cells and living R cells

Heat-killed S cells (control)

Living S cells (control)

Living R cells (control)

Living S cells

Healthy Mouse

Healthy Mouse

Mouse dies

Mouse dies


Hershey chase
Hershey & Chase

  • What is responsible for transformation?

    • Dumb question now, but not so at the time

    • Bacteriophages – viruses than infect bacteria

      • Consist of protein + DNA

      • Which is the transformative agent?


EXPERIMENT

Radioactive protein

Phage

Bacterial cell

DNA

Batch 1: radioactive sulfur (35S)

Radioactive DNA

Batch 2: radioactive phosphorus (32P)


EXPERIMENT

Empty protein shell

Radioactive protein

Phage

Bacterial cell

DNA

Batch 1: radioactive sulfur (35S)

Phage DNA

Radioactive DNA

Batch 2: radioactive phosphorus (32P)


EXPERIMENT

Empty protein shell

Radioactivity (phage protein) in liquid

Radioactive protein

Phage

Bacterial cell

DNA

Batch 1: radioactive sulfur (35S)

Phage DNA

Centrifuge

Pellet (bacterial cells and contents)

Radioactive DNA

Batch 2: radioactive phosphorus (32P)

Centrifuge

Radioactivity (phage DNA) in pellet

Pellet


Chargaff s rules
Chargaff’s Rules

In DNA:

[A] = [T] & [G] = [C]

  • Why would this be true?


Structural model of dna
Structural Model of DNA?

  • M. Wilkins & R. Franklin use X-ray crystallography to study molecular structure

  • Watson & Crick “deduced” that DNA was 2-stranded

    • Double Helix


Dna replication
DNA Replication

  • DNA  DNA

  • 2 strands separate, and each one is paired using complementary bases


Themes meh
Themes (meh.)

  • Science as a process

  • Regulation

  • Interdependence in nature

  • Science, Technology, & Society


Semiconservative replication
Semiconservative Replication

  • Each daughter molecule = 1 old strand (Conserved from parent strand) + 1 newly replicated strand

    • Called Semiconservative

    • Half of the strands are conserved from the parent

  • Competing (Incorrect models): Conservative & Dispersive


Dna replication1
DNA Replication

  • 16_05DNAandRNAStructure

  • 16_07DNADoubleHelix

  • 16_09Overview


Telomeres
Telomeres

  • Eukaryotic chromosomal DNA molecules have at their ends nucleotide sequences called telomeres

  • Telomeres do not prevent the shortening of DNA molecules, but they do postpone the erosion of genes near the ends of DNA molecules

  • It has been proposed that the shortening of telomeres is connected to aging

  • Telomerase – enzyme that lengthens the telomere

  • Telomerase in cancerous cells?


PROKARYOTE

EUKARYOTE


ad