6.1-2 Cell cycle & mitosis

Question 1

What is the role of mitosis and the cell cycle?

Answer 1

• to produce identical daughter cells for growth and asexual reproduction of cells

Question 2

What are all the cells produced by mitosis have in common?

Answer 2

• genetically identical

Question 3

What does mitosis have no involvement in?

Answer 3

• does not give rise to genetic variation
• DNA replication

Question 4

What is a simplistic version of the cell cycle?

Answer 4

• a cell forms
• it grows
• divides to form daughter cells

Question 5

What are the three phases of the cell cycle?

Answer 5

• mitosis
• cytokinesis
• interphase

Question 6

Mitosis is …

Answer 6

• a form of cell division that produces identical cells
• contains four phases

Question 7

What are the four phases of mitosis?

Answer 7

• prophase
• metaphase
• anaphase
• telophase

Question 8

Cytokinesis is when …

Answer 8

• new cell surface membrane forms down the centre of cell
• cleavage furrow starts to form, where the cell membrane constricts inwards to begin dividing the cytoplasm
• two new diploid genetically identical daughter cells produced

Question 9

Interphase is when …

Answer 9

• the mitochondria/ chloroplasts grows and prepares to divide to increase numbers
• DNA is replicated and checked for errors in the nucleus
• protein synthesis occurs in the cytoplasm
• chromosomes also begin to condense
• normal metabolic processes occur within the cell

Question 10

Prophase is when …

Answer 10

• the nuclear envelope disintergrates
  -DNA condenses to form chromosomes
• spindle fibres attach onto centromeres to begin moving the chromosomes to the centre of the cell
• centrioles move to opposite poles of the cell for the purpose of spindle formation

Question 11

Metaphase is when …

Answer 11

• chromosomes move to the equator
• attach to spindle fibres via centromeres
• ‘metaphase plate’

Question 12

Anaphase is when …

Answer 12

• the sister chromatids are separated as centromeres divide
• spindle fibres shorten
• chromatids attached to spindle fibres form little V shaped

Question 13

Telophase is when …

Answer 13

• nuclear envelope/ nucleolus reforms around each set of chromosomes
• spindle is broken down and disappears
• chromosomes become less condense
• chromatids reach the poles now called chromosomes

Question 14

What are the three roles of mitosis?

Answer 14

• growth and repair
• asexual reproduction
• binary fission (prokaryotes)

Question 15

What are the three stages of interphase?

Answer 15

• G1 (first growth phase)
• S (synthesis)
• G2 (second growth phase)

Question 16

G1 is when…

Answer 16

• protein synthesis
• new organelles are made (mitochondria and chloroplasts)
• cell grows in size

Question 17

Synthesis is when…

Answer 17

• DNA is replicated in the nucleus

Question 18

G2 is when …

Answer 18

• cell continues to grow in size
• energy stores are increased
• replicated DNA is checked for errors

Question 19

G1 checkpoint checks …

Answer 19

• cell size, enough nutrients, DNA damaged in phase
• if something is wrong cell enters G0 phase
• happens at end of G1 phase

Question 20

G2 checkpoint checks …

Answer 20

• happens at end of G2 phase
• checks that all DNA is replicated with no error
• if something is wrong cell enters G0 phase

Question 21

Spindle assembly (metaphase) checkpoint checks …

Answer 21

• checks that chromosomes are attached to spindles and aligned in the middle
• if something is wrong then the error is corrected at the next phase
• purpose of this checkpoint is to avoid aneuploidy

Question 22

Aneuploidy is …

Answer 22

• abnormal number of chromosomes in a cell