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Biology - Unit 1 > Nucleic acids > Flashcards

Flashcards in Nucleic acids Deck (25):
1

What do nucleic acids consist of?

A nitrogenous base, a phosphate and a sugar

2

How is the phosphate attached to the sugar?

A phosphoester bond

3

What is the difference between ribose and deoxyribose?

Ribose = OH on Carbon 2
Deoxyribose= H on Carbon 2

4

What is the structure of a purine?

Double ring

5

Which of the bases are purine?

Adenine and Guanine (pure agony)

6

What is the structure of pyrimidines?

Single ring structure

7

Which of the bases are pyrimidine?

Cytosine thymine and uracil

8

What are phosphates linked to deoxyribose sugars by?

Phosphodiester bonds

9

Which carbons does the phosphodiester bond form between?

3'-5'

10

What are the bases in each pair linked by?

Hydrogen bonds

11

What is the name given to describe the two chains which run in opposite directions?

Antiparallel

12

How many hydrogen bonds exist between Guanine and cytosine?

3

13

How many hydrogen bonds exist between adenine and thymine?

2

14

How can mRNA form base pairs

By looping back on itself

15

How many regions does tRNA have where base pairing is possible?

5

16

Where do polymerase enzymes add nucleotides to

The 3' end of a nucleotide

17

What shape is formed during DNA replication?

A replication fork

18

What direction is the leading strand competed in?

The 5' to 3' direction

19

What does replication begin with?

An RNA primer (replaced with DNA later)

20

What does DNA polymerase do with respect to the primer?

Adds a new DNA nucleotide to the 3' end and so starts to build the new DNA chain

21

What happens to the free nucleotides?

DNA polymerase matches them to their complementary bases on the template strand of DNA

22

What does DNA polymerase catalyse?

The formation of phosphodiester bonds between the end of the growing strand and the new nucleotides.

23

How is the phosphodiester bond formed?

When the OH of the 5' phosphate and the OH of the 3' deoxyribose are involved in a condensation reaction.

24

What is the lagging strand made in?

Short 5'-3' fragments

25

What does DNA ligase do?

Links the 5' to 3' fragments of the lagging strand together by catalysing the formation of phosphodiester bonds between the nucleotides at the end of the fragments