DNA replication, the cell cycle and mitosis Flashcards Preview

MCD - Nucleic Acids and Gene Expression > DNA replication, the cell cycle and mitosis > Flashcards

Flashcards in DNA replication, the cell cycle and mitosis Deck (25):
1

Initiation steps of DNA replication

- Topoisomerase unwinds DNA.
- DNA helicase unzips two strands, uses ATP to break H bonds between base pairs.

2

Leading strand synthesis process

- RNA primer placed at origin of replication
- DNA polymerase adds to RNA primer and synthesises continuously in a 5' to 3' direction.
- RNA primer is removed

3

Lagging strand synthesis process

- DNA primase synthesises multiple short RNA fragment primers
- DNA polymerase adds to RNA primer, starting Okazaki fragment
- Ribonuclease removes RNA primer after fragment completion.
- Repair DNA polymerase replaces RNA with DNA
- DNA ligase joins the two fragments together using ATP to make newly synthesised strand continuous

4

Name of starting point for replication

Origin of replication

5

Name of site of DNA synthesis

Replication fork

6

Role of sliding clamp in DNA replication

Ensures DNA polymerase stays attached during synthesis

7

Role of single-stranded DNA-binding proteins in DNA replication

Ensures DNA remains extended for replication

8

What is semi-conservative replication

Double-stranded daughter copies of parental DNA are made up of one strand from the parental DNA and a newly synthesised strand, complementary to the parental strand.

9

Process of proof-reading and correction in DNA replication

- Before a new nucleotide is added, previous nucleotide is checked for correct base-pairing
- Any incorrect bases are removed by 3' to 5' (opposite direction to synthesis) exonuclease activity of DNA polymerase
- New correct nucleotide added

10

Process of eukaryotic chromosome replication (and diagram see notes)

- Eukaryotic chromosomes are linear and very long
- Multiple origins of replication established around 100 kilo base pairs apart
- Each replication origin gives bi-directional replication forks
- Replication forks eventually meet to synthesis entirely new chromosome

11

E.coli chromosome replication process (and diagram see notes)

- Replication starts at unique origin
- Two replication forks proceed simultaneously in opposite directions
- Bacterial chromosomes are circular and continuous so replication forks eventually meet at the other side of the chromosome to where the origin is located

12

List cell cycle phases in order

M phase
G1 phase
- G0 phase
S phase
G2 phase

13

M phase features

Mitosis and cell division

14

G1 phase features

Gap phase 1
DNA in the form of a single linear double helix

15

S phase features

Synthesis phase
DNA synthesis and replication takes place

16

G2 phase features

Gap phase 2
Each chromosome has two identical sister chromatids produced by S phase ready for mitosis (M phase)

17

G0 phase features

Exits from G1 phase
Cells which have stopped dividing, apoptotic cells etc.

18

Mitosis phases in order

Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Interphase

19

Late prophase chromosome condition

Chromosomes condensed, each contains two sister chromatids

20

Metaphase chromosome condition

Chromosomes condensed, now aligned on the central plane of the spindle

21

Anaphase chromosome condition and process

Sister chromatids move to opposite poles of spindle. Centromere splits, ensuring each new cell gets one half of new chromosomes

22

Telophase chromosome condition and process

Two daughters cells formed with half of total chromosomes in each

23

Cytokinesis process

Division of cytoplasm

24

Interphase G1 begins after telophase, main feature

Condensation of chromosomes is reversed

25

Interphase G2 before prophase of mitosis, main feature

Chromosomes uncondensed and not visible but about to undergo condensation