Chapter 12

Question 1

what makes up chromatin

Answer 1

• one long DNA molecule
• proteins that maintain chromosome structure & control activity of genes

Question 2

what do chromatin eventually break down into

Answer 2

chromosomes

Question 3

what is the purpose of the centromere

Answer 3

join sister chromatids by the waist

Question 4

what are the two parts of the cell cycle

Answer 4

interphase (non-dividing)
mitotic phase

Question 5

what are the stages within interphase

Answer 5

G1
S
G2

Question 6

G1 phase

Answer 6

growth & increase in cytoplasm

Question 7

S phase

Answer 7

duplication of chromosomes

Question 8

G2 phase

Answer 8

growth & preparation for division

Question 9

what are the two stages of the mitotic phase

Answer 9

mitosis and cytokinesis

Question 10

mitosis

Answer 10

division of nucleus

Question 11

cytokinesis

Answer 11

division of cytoplasm and end up with 2 daughter cells

Question 12

what are the 5 subphases of mitotic phase

Answer 12

prophase
prometaphase
metaphase
anaphase
telophase

Question 13

what does “n” represent

Answer 13

how many different ones you get from mom and dad

Question 14

what is involved in prophase

Answer 14

centrosomes
centrioles
spindles

Question 15

interphase

Answer 15

• prep
• two centrosomes form
  chromosomes duplicate
• nucleoli form
• cytoplasmic contents double

Question 16

prophase

Answer 16

-microtubules begin to emerge
- form spindle
- nucleoli disappear
- chromosomes condense

Question 17

what is a mitotic spindle

Answer 17

organize microtubule arrangement
- produced by centrosomes
- required to divide chromosomes

Question 18

prometaphase

Answer 18

move chromosomes to center of cell
- spindle microtubules reach chromosomes
- nuclear envelop disappears

Question 19

metaphase

Answer 19

• mitotic spindle formed
• chromosomes align at middle
• face opposite poles

Question 20

anaphase

Answer 20

• sister chromatids separate
• daughter chromosomes moved to opposite poles
• cell elongates

Question 21

telophase

Answer 21

• nuclear envelope forms around each chromosome
• chromatin uncoils
• spindle disappears
• cytokinesis

Question 22

cytokinesis in animal cells

Answer 22

• cleavage furrow forms
  cleavage furrow deepens to separate contents

Question 23

cytokinesis in plant cells

Answer 23

cell plate forms in the middle from vesicles containing cell wall material
- cell plate grows outward to reach edges to divide cell
- each cell would now posses plasma membrane and cell wall

Question 24

how do bacteria divide

Answer 24

binary fission

Question 25

binary fission

Answer 25

- bacterial chromosomes replicate - proteins attach to chromosomes & separate them - proteins divide cytoplasm

Question 26

why does cell cycle length vary

Answer 26

due to variation of length of G1 phase

Question 27

what do rapidly dividing cells do to the G1 phase

Answer 27

eliminate it

Question 28

what happen to nondividing cells

Answer 28

get permanently stuck in G1 phase (G0)

Question 29

what can affect division rate

Answer 29

response to changing environment

Question 30

how is cell cycle regulated

Answer 30

through variation in length of cycle and division rates

Question 31

cell cycle checkpoints

Answer 31

allow for cycle to be regulated

Question 32

how do the cell cycle checkpoints work

Answer 32

Regulatory molecules at each checkpoint allow a cell to “decide” whether to proceed with division

Question 33

what happens if a cell cycle checkpoint fails

Answer 33

cancer and tumors

Question 34

cancer

Answer 34

- grow rapidly and uncontrolled - invade nearby tissues & spread rapidly - caused by defective cell cycle checkpoints

Question 35

what does mitosis start with and produce

Answer 35

- starts with diploid somatic cells - produce genetically identical daughter cells

Question 36

metaphase plate

Answer 36

during metaphase, chromosomes will line up on this plate at the center of the cell

Question 37

what is the purpose of the kinetochore

Answer 37

protein structure where the spindle fibers attach during division to pull the sister chromatids apart