cell cycle

Question 1

do cells divide again after they become specialised?

Answer 1

most types of cells never divide after specialisation

Question 2

what are the 3 phases of the cell cycle?

Answer 2

1. interphase
2. mitosis/meiosis
3. cytokinesis

Question 3

what are the 3 subphases of interphase?

Answer 3

1. G1 phase
2. S phase
3. G2 phase

Question 4

when does the G1 phase of interphase occur?

Answer 4

• immediately after cyotkinesis

Question 5

what does the cell do during the G1 phase of interphase?

Answer 5

• the cell synthesises RNA, enzymes & proteins required for growth
• the cell also grows & builds up a large store of materials for mitosis

Question 6

what occurs during the S phase of interphase?

Answer 6

• DNA replication!!

Question 7

what happens to the amount of DNA present in the cell after DNA replication?

Answer 7

• the amount of DNA present in the cell is now doubled

Question 8

what happens to the cell during the G2 phase of interphase?

Answer 8

• the cell synthesises proteins, including ribosomal proteins & proteins which make up the spindle fibres of the mitotic spindle
• the cell also forms new organelles, & the centrosome duplicates, in preparation for cell division

Question 9

what happens to all non-dividing specialised cells after the M phase?

Answer 9

• they exit the cell cycle & enter the G0 (resting) phase

Question 10

what does the term ‘cytokinesis’ refer to?

Answer 10

• it refers to the cytoplasmic division of a cell between the 2 nuclei, bringing about the separation into 2 daughter cells

Question 11

are cytokinesis & mitosis/meiosis separate process?

Answer 11

• YES
• cytokinesis accompanies mitosis, usually at the beginning of telophase

Question 12

what happens to animal cells during cytokinesis?

Answer 12

• a contractile ring made of actin filaments, surround the dividing cell
• as the contractile ring contracts, it pulls the cell surface membrane inwards to form a cleavage furrow
• the cleavage furrow deepens & eventually separates to form 2 daughter cells

Question 13

what happens to plant cells during cytokinesis?

Answer 13

• a series of Golgi vesicles appear in the middle of the parent cell
• they fuse together to form the cell plate, which grows outwards, and the cell plate eventually fuses with the parent cell wall & cell surface membrane, separating the 2 daughter cells