1030- The cell cycle

Question 1

What is the purpose of the cell cycle - 4 points

Answer 1

To copy the genome and to divide these copies equally between the daughter cells, to replace lost or damaged cells, to allow multicellular organisms to grow to an adult size, to maintain the total cell number of an adult organism.

Question 2

Process of binary fission

Answer 2

DNA attaches to the cytoplasmic membrane , cell enlarges and the DNA duplicates , septum forms and cells divide into 2 and DNA is partitioned into 2 cells. Cells separate.

Question 3

How long does cell division and DNA replication take?

Answer 3

Cell division -20 mins ,DNA replication -40

Question 4

Replication of DNA process

Answer 4

There is one origin of replication on a DNA circular chromosome , 2 replication forks form at the origin and replication is bidirectional forming two identical copies of the circular chromosome.

Question 5

Cytokinesis process

Answer 5

ftsz is distributed randomly throughout the bacterial cell , then forms a ring protein at the inner surface of the cytoplasmic membrane ,ftsZ ring then contracts forming 2 separate bacterial prokaryotic cells.

Question 6

purpose of multifork replication

Answer 6

to ensure at least one round of replication is finished before cytokinesis.

Question 7

G1 phase

Answer 7

growth face - doubling the mass of organelles and proteins , increasing the amount of enzymes available for DNA replication.

Question 8

S phase

Answer 8

DNA synthesis phase with chromosomal mutations

Question 9

What ensures that sister chromatids do not drift apart?

Answer 9

Cohesin

Question 10

What occurs during interphase

Answer 10

Chromosomes are not visible

Question 11

What is Prophase and explain what condensin does

Answer 11

Chromosomes condense and become visible: condensin encircles loops of DNA to compress the sister chromatids and give a compact structure.

Question 12

kinetochore

Answer 12

complex of proteins attached to the centromere

Question 13

How do the sister chromatids get pulled apart?

Answer 13

when the klesin subunit of cohesin is cleaved by a protease.

Question 14

What are the basic processes common to all cell cycles? What do variations include

Answer 14

DNA replication must be done faithfully and the chromosomes must be segregated. Variations include timings.

Question 15

In what conditions will the cell cycle stop?

Answer 15

if the cell is deprived of nutrients, if the DNA is damaged or if the chromosomes fail to attach to the spindle.

Question 16

g1/s

Answer 16

cyclin E

Question 17

M phase cyclin

Answer 17

cyclin B

Question 18

purpose of checkpoints

Answer 18

to ensure the next phase isn’t initiated without the previous one finishing first

Question 19

What happens to the cycle when the DNA gets damaged

Answer 19

Cycle keeps turning despite DNA damage. Mutations

accumulate. Leads to cancer.

Question 20

What happens to the cells, checkpoints and start and stop signals with people who have cancer?

Answer 20

cells do not communicate with each other, checkpoints which protect the genome do not operate , start and stop signals for the cell cycle do not operate correctly.