Presentation is loading. Please wait.

Presentation is loading. Please wait.

© 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 1 The Search for Genetic Material Early geneticists didn’t know what the genetic material was,

Published byMartina Bennett Modified over 9 years ago

Similar presentations

Presentation on theme: "© 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 1 The Search for Genetic Material Early geneticists didn’t know what the genetic material was,"— Presentation transcript:

1 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 1 The Search for Genetic Material Early geneticists didn’t know what the genetic material was, what carried genes The genetic material needed to:  Contain information  Be able to be copied easily  Be variable to account for diversity

2 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 2 Was it DNA or Protein? Geneticists thought that Chromosomes might carry the genes (from mitosis)  Composed of DNA and protein Which is the genetic material?  Protein is large, complex and stores info  DNA seemed too small and simple

3 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 3 Griffith’s Experiment Two strains of bacteria  R – harmless (1)  S – deadly (2) Heat killed Strain S is also harmless (3) Something from heat killed Strain S makes Strain R deadly (4)

4 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 4 Avery, MacLeod, and McCarty Isolated compounds from Strain S Added these to Strain R DNA transformed Strain R into Strain S Proved DNA was the genetic material

5 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 5 DNA, Genes, & Chromosomes Inside a cell, we have chromosomes Each chromosome is made up of one molecule of DNA and many proteins Along the DNA are regions that code for information (genes) Animation of this relationship Animation

6 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 6 Watson & Crick Determined the 3-D structure of DNA  Structure revealed its function X-ray crystallographic studies showed that  Double helix  Ladder twisted into a spiral coil

7 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 7 The Double Helix Two long strands of nucleotides Sugar-phosphate backbone Base-pairing holds the strands together

8 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 8 Base-Pairing Rules Strands held together by base-pairing  Hydrogen bonds between bases Strict base-pairing rules:  A binds to T  G binds to C Makes copying the sequence possible

9 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 9 Fulfills Three Requirements Contains info of the genetic material  Sequence of bases stores this info Easily copied  Each strand is a template for the other Accounts for diversity  Alleles have different DNA sequences

10 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 10 Individuals have slight differences in sequence Different species have greater differences Variation & Diversity Person 1 Person 2 Chicken

11 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 11 DNA Replication DNA Synthesis during S- phase of Interphase H-bonds between 2 strands are broken Two Strands separate Each strand is a template for the other

12 DNA Synthesis & Replication: DNA “unzips” Two opposite strands separate Matching bases are added to each side Result: Two copies of the original DNA molecule

13 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 13 Many enzymes and proteins are involved  Initiate replication  Unwind the DNA -helicase  Stabilize the open strands  Add & connect bases to form backbone (DNA polymerases) Enzymes also needed to correct mistakes Mistakes result in mutation DNA Replication

14 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 14 Two Types of Mutations Base Changes  A change in the sequence of nucleotide bases  Most are silent (do not change a protein) Chromosomal Abnormalities (macro- mutations)  Large changes in whole regions of DNA  Most are lethal

15 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 15 Base Mutations Incorrect base-pairings that are not fixed  Mutagens increase the frequency Next replication includes these changes Source of new alleles (new variation)  A few are beneficial (make a better protein)  Most are silent (make no change in a protein)  Some are harmful (most that change a protein)

16 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 16 Mutations Ask for examples of mutant human genes Bad mutations include ->  sickle cell anemia, hemophilia, color blindness. Can you find a mutation in this picture?mutation in this picture

17 Mutations There at least two mutations -> blue eyes, white skin (occurred long ago).

18 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 18 DNA Repair DNA polymerases often insert incorrect bases  DNA mismatch Proofreading enzymes correct mistakes

19 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 19 DNA Repair Enzymes recognize damaged DNA Cut the backbone on either side Damaged DNA is removed DNA is corrected

20 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 20 Inherited Repair Disorders Xeroderma pigmentosum

21 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 21 The Griffith experiment showed that A. Something heritable was being passed between the bacterial strains. B. DNA was the genetic material. C. Protein was the genetic material. D. Strain S was lethal to mice. Concept Quiz

22 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 22 Watson and Crick showed that A. A binds to T and G binds to C. B. One strand is a template for the other strand. C. The DNA molecule can be easily replicated. D. All of the above. Concept Quiz

23 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 23 DNA repair is A. Only important during replication. B. Found in some species. C. Vital to maintaining DNA’s integrity. D. An inherited disorder. Concept Quiz

24 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 24 Process Animation 12.1a DNA Repair: Mutations from DNA Replication  Macintosh Macintosh  Windows Windows

25 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 25 Process Animation 12.1b DNA Repair: Mutations from Sunlight  Macintosh Macintosh  Windows Windows

Download ppt "© 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e 1 The Search for Genetic Material Early geneticists didn’t know what the genetic material was,"

Similar presentations

DNA: The Genetic Material

DNA: The Genetic Material
Discovering DNA: Structure and Replication

Discovering DNA: Structure and Replication
1 DNA and Replication. 2 History of DNA Early scientists thought protein was the hereditary material –Protein is more complex than DNA –Proteins are composed.

1 DNA and Replication. 2 History of DNA Early scientists thought protein was the hereditary material –Protein is more complex than DNA –Proteins are composed.
Chapter 9 DNA: THE Genetic Material. Transformation Frederick Griffith, a bacteriologist, prepared a vaccine against pneumonia Vaccine – a substance that.

Chapter 9 DNA: THE Genetic Material. Transformation Frederick Griffith, a bacteriologist, prepared a vaccine against pneumonia Vaccine – a substance that.
DNA and Heredity. DNA and Heredity DNA is found in the cell’s __nucleus_______. DNA is found in the cell’s __nucleus_______. In the nucleus, we find the.

DNA and Heredity. DNA and Heredity DNA is found in the cell’s __nucleus_______. DNA is found in the cell’s __nucleus_______. In the nucleus, we find the.
In 1928, Frederick Griffith, a bacteriologist, was trying to prepare a vaccine against pneumonia.

In 1928, Frederick Griffith, a bacteriologist, was trying to prepare a vaccine against pneumonia.
Chapter 12.  1928 – Griffith  Discovered bacteria transferred something between them that changed them into a new strain.  Called this “bacterial transformation”.

Chapter 12.  1928 – Griffith  Discovered bacteria transferred something between them that changed them into a new strain.  Called this “bacterial transformation”.
Discovering DNA: Structure and Replication

Discovering DNA: Structure and Replication
DNA Structure and Function Chapter 12. Discovery of DNA Nucleic Acids were discovered in 1869 by Friedrich Mieschner as a substance contained within nuclei.

DNA Structure and Function Chapter 12. Discovery of DNA Nucleic Acids were discovered in 1869 by Friedrich Mieschner as a substance contained within nuclei.
What we’ve learned so far… Cells make proteins Genetic information is passed on through chromosomes Compacted DNA and proteins= chromosomes Genetic information.

What we’ve learned so far… Cells make proteins Genetic information is passed on through chromosomes Compacted DNA and proteins= chromosomes Genetic information.
DNA: The Genetic Material

DNA: The Genetic Material
DNA, PROTEIN SYNTHESIS, & Mutations Chapters 12 Pages 287-308.

DNA, PROTEIN SYNTHESIS, & Mutations Chapters 12 Pages
DNA Chapter 12. DNA  Holds our ______________ ______________  Like a ______________  Important for ______________ to occur  Biologists had to discover.

DNA Chapter 12. DNA  Holds our ______________ ______________  Like a ______________  Important for ______________ to occur  Biologists had to discover.
Chapter 12: DNA The Blueprint of Life.

Chapter 12: DNA The Blueprint of Life.
Gene Expression & DNA Replication DNA must be copied so that the DNA is the same in all cells Differences in gene expression give rise to: – different.

Gene Expression & DNA Replication DNA must be copied so that the DNA is the same in all cells Differences in gene expression give rise to: – different.
Goal: Students will be able to explain how DNA was identified as the genetic material, describe the basic processes of replication, transcription, and.

Goal: Students will be able to explain how DNA was identified as the genetic material, describe the basic processes of replication, transcription, and.
DNA Replication. Cell Division and DNA Replication Cells divide -->Growth, Repair, Replacement Before cells divide they have to double cell structures,

DNA Replication. Cell Division and DNA Replication Cells divide -->Growth, Repair, Replacement Before cells divide they have to double cell structures,
DNA Chapter 12. GENETIC MATERIAL In the middle of the 1900’s scientists were asking questions about genes. What is a gene made of? How do genes work?

DNA Chapter 12. GENETIC MATERIAL In the middle of the 1900’s scientists were asking questions about genes. What is a gene made of? How do genes work?
DNA Chapter 12. DNA  Holds our genetic information  Like a library  Important for mitosis to occur  Biologists had to discover the chemical nature.

DNA Chapter 12. DNA  Holds our genetic information  Like a library  Important for mitosis to occur  Biologists had to discover the chemical nature.
DNA Structure and Replication Genetics DNA Can replicate Is the hereditary material Controls cellular activities by coding for and controlling protein.

DNA Structure and Replication Genetics DNA Can replicate Is the hereditary material Controls cellular activities by coding for and controlling protein.

Similar presentations

Ads by Google