The cell cycle

Question 1

what is a stem cell

Answer 1

an undifferentiated cell which can actively go through the cell cycle

Question 2

define differentiation

Answer 2

the physical change of a cell into a final specialised form

Question 3

what are specialised cells

Answer 3

cells with a designated shape, chemistry and role

Question 4

which cells do not go through mitosis

Answer 4

differentiated cells

Question 5

how are new cells formed from our tissues

Answer 5

all tissues contain a base layer of stem cells which differentiate to replace any cells that have died

Question 6

how many chromosomes in a single dna molecule

Answer 6

one

Question 7

how many chromosomes in two sister chromatids attached by a protein complex (two dna molecules)

Answer 7

one

Question 8

when and how are chromosomes visible

Answer 8

they are visible when supercoiled and can be seen under a light microscope

Question 9

Name the states of the cell cycle

Answer 9

• interphase (G1)
• interphase (S)
• interphase (G2)
• mitosis
• cytokinesis

Question 10

Describe what occurs during interphase (G1)

Answer 10

Cell increases in mass, duplicates all cellular contents and organelles excluding chromosomes

Question 11

What occurs during interphase (S)

Answer 11

Semi-conservative dna replication of all 46 chromosomes

Question 12

What occurs during interphase (G2)

Answer 12

Cell double checks that both S and G1 have been fully completed. Makes any needed repairs.

Question 13

What is mitosis

Answer 13

Nuclear division

Question 14

What is cytokinesis

Answer 14

Division of the cell body

Question 15

What state are chromosomes in during interphase

Answer 15

Diffuse and uncoiled (to unwind and separate)

Question 16

What state are chromosomes in during mitosis

Answer 16

Short, compact - supercoiled
(More compact so can separate within the confides of the cell)

Question 17

What is a chromatin

Answer 17

DNA molecules associated with proteins called histones

Question 18

Name the stages of mitosis

Answer 18

• prophase
• metaphase
• anaphase
• telophase

Question 19

Describe what happens during prophase

Answer 19

(Occurs at different rates)
- nuclear envelope disintegrates
- nucleolus disintegrates
- spindle fibres form (forming a spindle)
- chromosomes condense and coil becoming visible

Question 20

Describe what happens during metaphase

Answer 20

• chromosomes attach to the spindle via their centromeres
• centromeres break
• line on the equatorial plane

Question 21

Describe what happens during Anaphase

Answer 21

• sister chromatids are pulled to opposite sides of the cell

Question 22

Describe what happens during telophase

Answer 22

• two new nuclear envelopes form
• Chromatin/dna becomes diffuse
• nucleolus reforms

Question 23

What is the phase between prophase and metaphase called

Answer 23

Prometaphase

Question 24

Why does metaphase not slide into anaphase

Answer 24

The chromatids must be separated at the same time, the cell has to check that all chromosomes are attached before separating