Biology 1 semester study guide

DNA stands for - Deoxyribonucleic acid


Griffith’s Experiments 


Types of Macromolecules-

  • Carbohydrates

  • Lipids

  • Proteins

  • Nucleic Acids


How did the mice from the 4th group die if S strain bacteria was dead?

  • Transformation - process by which one strain/type of bacteria was changed into another strain

    • Harmless strain to disease causing strain

  • Offspring of transformed bacteria were disease causing 

  • Conclusion- transforming factor had to the a gene


Oswald Avery - 

  • Extracted and destroyed different macromolecules from heat killed bacteria to see if transformations still occurred

  • Conclusion - the nucleic acid dna DNA stores and transmits genetic info from one generation of bacteria to the next

    • Nucleic Acid (DNA) - the only one that has a living mice




13.2 The Structure of DNA - (CONT.)


Bacteriophage - a virus that infects bacteria 

      ⬇ (ties into Hershey and Chase)

Hershey - Chase Experiment 

  • Experiment to determine whether protein coat or DNA was injected iron cell

  • Confirmed Avery’s result and convinced scientists that DNA was genetic material found in all genes of all organisms 




SUMMERY - 


Griffth- That compounds can be passed from one parent organism to another parent organism (transformation)

         -Since offspring of R strain also had the transformed compound, the compound must be a gene

Still don’t know what genes are made of yet

 Avery- discovered that genes are made of nucleic acids, specifically DNA  in bacteria

  • Prior to Avery no one knew which macromolecule genes where made of

Hershey and Chase- experimented with radioactive bacteriophages

  • Tested to see if DNA or protein was injected by bacteriophage into bacteria.

  • DNA was injected into bacteria thus proving Avery’s claim that genes are made of DNA and convincing scientists that genes in all living cells (bacteria, virus, plants, animals) was made of DNA

 Other terms: Transformation, bacteriophage







Structure of DNA - 13.2


Components of DNA

  • What macromolecules and monomers?


Purines:

Guanine 

Adenine 


Pyrimidine: (the “y”)

Cytosine 

Thymine 




Chargaff’s Rules


A = T and G = C


          100%

A       T        G      C

20%     20%        30%       30%



DNA Structure - 


G = A  OR  C = T -  WOULD NOT WORK (would not be equal)

  • Big and big 

  • Small and small


Rosalind Franklin - 

3 dimensional image (photo 51) 

What the image shows - 

  1. “X” shape shows Helix (twist)

  2. 2 strands (double helix)

  3. Dark spots show nitrogenous bases located at the center - middle of DNA molecule

 

The Double Helix Model

  • The 2 strands of DNA run anti-paralle, opposite directions

  • Hydrogen Bonds connecting the DNA together

  • The sugar phosphate is the “back bone”

  • Nitrogenous bases “sides of the ladder”

  • 5 carbon sugar called - deoxiribous 


Reading DNA

  • Always start on the 5’ end on the left and 3’ end ( ‘ = prime)

5’ C C T - G A T  3’

         3’  G G A   C T A  5’