CHP 11: Molecular Structure of DNA and RNA

What is Griffith’s Transforming Principle?

It demonstrated that bacteria can transfer genetic material

What was Griffith’s experiment?

Inject dead smooth bacteria and living rough bacteria into mice

What was the result of Griffith’s experiment?

Smooth bacteria was removed (rough bacteria was acquiring traits from the dead smooth bacteria)

What was the smooth bacteria?

Pathogen

What was the rough bacteria?

Not a pathogen

Avery, Macleod, and McCarty’s experiments were based on…

Griffith’s experiments

What did Avery, Macleod, and McCarty do?

Extracted material from smooth bacteria and mixed it with rough bacteria

What did Avery, Macleod, and McCarty find?

When RNA proteins were destroyed, rough still became smooth. When DNA was destroyed, rough bacteria did not become smooth.

What did Avery, Macleod, and McCarty’s discoveries suggest?

DNA was the inherited molecule

What were the Hershey-Chase experiments?

Infecting bacteria with viruses in attempt to prove that DNA is the genetic material of living organisms

Nucleic Acids

A chain of nucleotides which forms the repeating structure of nucleic acids

Nucleotides

Building blocks of nucleic acids

What are nucleotides composed of?

Five carbon sugar, phosphate group, and nitrogenous base

When nucleotides are linked they form…

A strand of DNA or RNA

When two strands of DNA interact they form…

A double helix

A double helix forms

A chromosome

In nucleotides the carbons in sugar are numbered…

1’ to 5’

1’

Where the base attaches

3’

Has -OH and is where new nucleotides attach

5’

Has phosphate, which is what attaches to the 3’ -OH of another nucleotide

Nucleic acids are held together by

Phosphodiester bonds

The linkage of nucleic acids creates a…

Phosphate-sugar backbone

Strands have directionality

‘5 end and ‘3 end

Pauling

Proposed DNA occurred in a helix based on molecular modeling (triple helix)

Franklin and Wilkins

Performed x-ray diffraction, which suggested a helical structure too wide to be a single strand

Chargaff

Discovered that the amount of T in DNA always matched the amount of A, and C always, matched G

Watson and Crick

Used information to determine the structure of DNA, how it is replicated, and how it is involved in producing phenotypes

The double strand in DNA occurs because…

Bases interact with each other through hydrogen bonds

Hydrogen Bonds

A only pairs with T and C only pairs with G

A and T Bond

2 H bonds

C and G Bond

3 H bonds

DNA strands are

Complementary and Antiparallel

RNA

Single stranded in cells

DNA

Double stranded in cells

RNA has

Ribose and Uracil

Uracil

Pairs with Adenine in RNA

Thymine

Pairs with Adenine in DNA

RNA Secondary Structure

RNA strands can fold in themselves due to hydrogen bonding between complementary bases