B1b Cell cycle

Question 1

List the stages that occur during interphase

Answer 1

G1 - growth

S - synthesis of DNA

G2 - growth & preparation for mitosis

Question 2

When in the cell cycle does DNA replication take place?

Answer 2

Interphase

S phase

Question 3

Describe the structure of a chromosome at prophase.

Answer 3

Two identical chromatids joined by a centromere

Question 4

What happens during interphase?

Answer 4

DNA replication
Replication of cell organelles
Store of ATP synthesised
Growth of cell

Question 5

Describe what happens in prophase

Answer 5

DNA condenses onto histones
Chromosomes become visible

Question 6

What happens during metaphase?

Answer 6

Chromosomes move to the equator of the cell.
Centromere attaches to the spindle fibres.

Question 7

Describe what happens during anaphase.

Answer 7

Spindle fibres pull chromatids to opposite poles of the cell.

Question 8

Describe what happens at telophase

Answer 8

Chromosomes/chromatids arrive at the poles of the cell.

Question 9

What happens during cytokinesis?

Answer 9

Cytoplasm divides to form two new cells.

Question 10

Which stage of mitosis is shown in the diagram?

Answer 10

Anaphase

Question 11

Which stage of mitosis is shown in the diagram?

Answer 11

Metaphase

Question 12

Name the stage of mitosis shown in the photograph.

Answer 12

Metaphase

Question 13

What is the cause of tumour and cancers?

Answer 13

Uncontrolled mitosis.

Question 14

Name the process used when eukaryotic cells divide?

Answer 14

Mitosis

Question 15

Name the process used when prokaryotic cells divide.

Answer 15

Binary fission.

Question 16

Describe the process of binary fission

Answer 16

Replication of circular DNA and plasmids.
Division of cytoplasm to form two daughter cells each with a single copy of the circular DNA and a variable number of copies of plasmids.

Question 17

How do viruses make copies of themselves?

Answer 17

Inject DNA or RNA into host cell.
Host cell replicates DNA or RNA.
Host cell makes viral proteins.
Host cell constructs new virus particles.

Question 18

Cancer is caused by uncontrolled mitosis.

How do most cancer drugs work?

Answer 18

Prevent DNA replication inhibiting metaphase by interfering with spindle formation

Question 19

Describe the cells produced by mitosis

Answer 19

2 daughter cells that have the same number of chromosomes as the parent cell and each other.
Genetically identical

Question 20

How much of a single cell cycle is spent in interphase?

Answer 20

90%

Question 21

How long does a mammalian cell take to undergo 1 complete cell cycle?

Answer 21

Approx. 24 hours.

Question 22

Why are cells taken from the root tip when studying mitosis?

Answer 22

Area of root growth
Meristem = place where mitosis/cell division occurs.

Question 23

When studying mitosis why do you firmly squash the root tip?

Answer 23

To create thin layer of cells /one cell thick
Allow light to penetrate the specimen

Question 24

How can you tell when a cell has undergone DNA replication?

Answer 24

Chromosomes become visible as X shaped structures - 2 sister chromatids joined by a centromere.

Question 25

How can you make the mitotic index accurate?

Answer 25

Systematic method of counting a large number of cells so the sample is representative.