1.5 Nucleic Acids Flashcards Preview

Biology 7401/2 > 1.5 Nucleic Acids > Flashcards

Flashcards in 1.5 Nucleic Acids Deck (16):
1

What is DNA?

Deoxyribonucleic acid and holds the genetic information

2

What is RNA?

Ribonucleic acid which translates and transfers the genetic information to the ribosomes.

3

What is a nucleotide?

A monomer made out of a base, a pentose sugar (deoxyribose or ribose) and a phosphate group

4

What is a base?

An organic base (contains nitrogen) is either A,G,C,T (T is substituted for U)

5

What is a pyramidine?

A single ring base- Cytosine and Thymine

6

What is a purine?

A single ring base- Adenine and Guanine

7

Which bases are complimentary?

A and T form 2 H Bonds
G and C form 3 H Bonds

8

What is the backbone and its function?

The backbone is the phosphate sugar molecule and it is rigid and strong whilst protects the inner bases?

9

What is meant by an antiparralel backbone?

The direction of the backbone flips (imagine one of the sugars as an upside down house) this is because the bonds run 3' to 5' on one side and 5' to 3' on the other

10

What replaces Thymine in RNA?

Uracil

11

What is semiconservative replication?

DNA replicates by using 1 side of the double helix as a template for the new strand.

12

How is DNA unwound?

DNA Helices breaks the H bonds in between the bases of the 2 strands. This makes 2 single strands.

13

How is DNA replicated?

Complimentary base pairs of free nucleotides line up alongside one of the original strands

14

How are the 2 strands formed?

Condensation reactions join the nucleotides of the new strand together, catalysed by DNA polymerase. H Bonds form between the old and new strand and the helix rewinds.

15

Which direction does DNA polymerase work in?

It works from 3' to 5' so there is a leading strand. A lagging strand (5' to 3') is built in fragments and require DNA Ligase to 'glue' these fragments together.

16

What is Meselson and Stahls experiment?

They grew DNA in light nitrogen to produce light strands of DNA then allowed them to replicated in heavy nitrogen. This caused the different type of nitrogen strands to separate to different densities when centrifuge. They found they had 3 types of DNA light, heavy and mix. This showed semiconservative replication.