Lecture 1: Nucleic acid structure and replication Flashcards Preview

2014 Genetics Topic 2: GL > Lecture 1: Nucleic acid structure and replication > Flashcards

Flashcards in Lecture 1: Nucleic acid structure and replication Deck (16)
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1

What are the 4 heterocyclic bases that make up the DNA sequence?

Adenine, Thymine, Guanine, Cytosine

2

What is a purine and what are the 2 heterocyclic bases examples?

A purine consists of 2 rings;a double ringed crystalline base: Adenine, Guanine

3

What is a pyrimidine and what are the 2 heterocyclic base examples?

A pyrimidine consists of one ring, crystalline base:
Cytosine, Thymine

4

How many hydrogen bonds form between C-G and what is consequence of this?

3 Hydrogen bonds form between C-G in comparison to A-T which bonds to each other with 2 hydrogen bonds. In consequence C-G requires more energy to separate.

5

what is the DNA backbone made of

2'- deoxyribose

6

What orientation does the DNA double helix conform to?

Right handed helix

7

What are the major components of RNA and how are DNA and RNA different?

RNA is one stranded
thyamine is replaced by uracil
ribose sugar instead of deoxyribose

8

true or false, DNA bases are hydrophobic

true

9

What is the consequence of the hydrophobic property of DNA bases?

They will tend to form a structure which removes them from an aqueous environment (double helix)

10

true or false, DNA soluble in water

true, this is because the DNA backbone is hydrophilic because it exposes its sugars

11

What do you call the process in which DNA is wound?

Supercoiling

12

What is a twist (T)

A twist is the number of turns (always + ve)

13

What is a writhe (W)

It is the number of times strip crosses over itself (always -)

14

What is the link number (L)

W+T

15

what enzyme breaks the ddsDNA and pass another part of the strands through the gap?

Type II Topomerases

16

which region on the DNA strand binds more strongly?

regions with high G-C content