1.2 Structure and Replication of DNA Flashcards Preview

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Flashcards in 1.2 Structure and Replication of DNA Deck (20)
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1

Describe the structure of a DNA molecule

•Made up of repeating nucleotides
•Bases of adenine, thymine, cytosine and guanine

2

Specific DNA base pairings

Adenine and Thymine
Cytosine and Guanine

3

Bonds that hold the nucleotides together

Sugar-phosphate bonds which form a strong sugar-phosphate backbone

4

Describe the structure of a DNA nucleotide

•Deoxyribose sugar molecule
•Phosphate group
•DNA base

5

Number of carbons in a DNA molecule

5

6

Name the structure that forms when the two strands of DNA wind around each other

Double helix

7

The meaning of antiparallel

The two DNA strands running in opposite directions, one strand running for 3' to 5', the other running from 5' to 3'

8

What chromosomes consist of

DNA tightly coiled around associated proteins

9

What base sequences of DNA code for

Genetic information
(Base sequence of DNA determines the amino acid sequence which determines the proteins produced, determining the structure and function of the cell)

10

Define triplet

A group of 3 DNA bases

11

What each triplet codes for

A specific amino acid

12

Before cell division, what happens to the DNA molecule

The DNA molecule is replicated

13

What enzyme the DNA molecule is replicated by

DNA polymerase

14

Where DNA replication takes place on the DNA strand

Several locations on the DNA molecule

15

Why DNA replication is important

To ensure that each new daughter cell recieves a full set of chromosomes and so no genetic information is lost

16

What must be present for DNA replication to occur

•DNA to act as a template
•Primers - a short complementary strand of nucleotides that allows DNA polymerase to bind
•Enzymes- DNA polymerase and ligase
•ATP for energy

17

The only end of a strand that DNA polymerase can add free complementary nucleotides to

3' end of a strand

18

How the leading strand is replicated

Continuously

19

How the lagging strand is replicated

In fragments which are joined together by ligase

20

Functions of DNA polymerase

•Adds nucleotides to the new strand
•Only adds nucleotides to an existing chain
•Can only add nucleotides to the deoxyribose 3' end