the cell cycle and it's control(this should be in PJ1311)

Question 1

cell cycle

Answer 1

defined as ordered sequences of events that occurs in the cell in preparation of cell division

Question 2

what are the two basic functions of the cell cycle

Answer 2

Copying cellular components and DNA duplication
Dividing the cell so that components are distributed evenly to the daughter cells

Question 3

do all cells divide?

Answer 3

No some cell can’t divide e.g, eye lens, nerve cell, heart cells.

Question 4

in unicellular cells, what does the division of one cell result to

Answer 4

the reproduction of the entire organism

Question 5

multicellular organisms depend on the cell cycle for?

Answer 5

growth of cells and the organism itself
maintenance of cells
repair of damaged cells

Question 6

what happens at the G0 phase

Answer 6

Resting phase where cell has left cycle &has stopped dividing

Question 7

what happens at the G1 phase

Answer 7

1st stage of Cell growth after cell division Preparation of chromosomes for replication
Duplication of cellular components (cytoplasm and organelle)
Cell carries on its normal metabolic activities
G1 checkpoint (or restriction point); cell commits to division or exits from cell cycle

Question 8

how many phases are there during interphase, name them

Answer 8

3 phases
G1
S
G2

Question 9

what happens during the S phase

Answer 9

DNA replication

Question 10

by which mechanism does DNA replication occur

Answer 10

semi-conservative

Question 11

is cytokinesis part of mitosis

Answer 11

no, it follows mitosis

Question 12

in which direction does the synthesis of DNA occur

Answer 12

from the 5’ end to the 3’ end

Question 13

which molecule is required to initiate DNA synthesis

Answer 13

a primer

Question 14

primer

Answer 14

short strand of DNA or RNA that serves as a starting point for DNA synthesis during replication

Question 15

function of ligase

Answer 15

unwinds parental double helix

Question 16

functions of binding proteins

Answer 16

they stabilise separate strands of the DNA double helix

Question 17

primase function

Answer 17

add a primer to the template strand

Question 18

DNA polymerase function

Answer 18

binds nucleotides to form new strands

Question 19

DNA polymerase I (exonuclease) function

Answer 19

removes RNA primer and inserts the correct bases

Question 20

ligase function

Answer 20

joins Okazaki fragments and seals in the sugar-phosphate backbone

Question 21

what are some general features of DNA replication

Answer 21

DNA replication is semi conservative
It is bidirectional process
It proceed from a specific point called origin
It proceed in 5’-3’ direction
It occur with high degree of fidelity
It is a multi-enzymatic process

Question 22

mitosis

Answer 22

process by which cell separates chromosomes in its cell nucleus into two identical sets in two nuclei

Question 23

duplicated chromosomes are known as?
what are they held together by

Answer 23

chromatids
centromere

Question 24

what happens during the G2 phase

Answer 24

All cell structures needed for division are made (e.g.centrioles)
Both organelles & proteins are synthesized
Checkpoint for entry into M phase

Question 25

name the stages of mitosis

Answer 25

prophase
prometaphase
metaphase
anaphase
telophase

Question 26

what happens during prophase

Answer 26

nuclear membrane disintegrates and the nucleolus disappears
the chromosomes condense
mitotic spindle begins to form
kinetochores begin to mature and attach to spindle

Question 27

how many checkpoints do we have in interphase

Answer 27

3-4

Question 28

the function of G2 checkpoint

Answer 28

to check for DNA damage and repair it