chapter twelve

Question 1

what does cell division result in?

Answer 1

2 daughter cells

Question 2

what is the purpose of cellular division?

Answer 2

reproduction, growth, repair

Question 3

unicellular cell division

Answer 3

clones
- ex. amoeba

Question 4

multicellular cell division

Answer 4

• reproduction (some organisms that don’t form gametes - asexual/sexual)
• growing (embryo, new blood cells)
• differentiating (which genes where expressed when)
• repair

Question 5

genome

Answer 5

a cell’s DNA/genetic information

Question 6

chromatin

Answer 6

entire complex of DNA and proteins that make up chromosomes

Question 7

what is the purpose of protein in DNA?

Answer 7

combats negative charge of nucleotides

Question 8

chromosomes

Answer 8

structures composed of chromatin
- eukaryotic (long DNA molecule w/ many proteins)
- after S phase, they have sister chromatids

Question 9

sister chromatids

Answer 9

joined copies of the original chromosome
- attached by cohesions

Question 10

centromere

Answer 10

region made up of repetitive sequences in the chromosomal dNA where the chromatid is attached most closely to a sister chromatid
- where kinetochores bind

Question 11

homologous chromosomes

Answer 11

pair of chromosomes that have same order of genes but with some variation

Question 12

somatic cells

Answer 12

diploid
- 2n number of chromosomes

Question 13

gametes

Answer 13

haploid
- n number of chromosomes

Question 14

mitosis

Answer 14

division of genetic material in the nucleus

Question 15

cytokinesis

Answer 15

division of the cytoplasm
- follows mitosis

Question 16

what do the cell division cycles consist of?

Answer 16

alternating M ( mitotic - mitosis/cytokinesis) phase with interphase (90% of cycle)

Question 17

3 phases of interphase

Answer 17

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

Question 18

G1 phase

Answer 18

first gap, metabolic activity/growth

Question 19

S phase

Answer 19

“replication”, synthesis/duplication of chromosomes, metabolic activity

Question 20

G2 phase

Answer 20

second gap, metabolic activity/growth, preparation for division

Question 21

stages of mitosis

Answer 21

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase

Question 22

spindle

Answer 22

fibers made of microtubules and proteins
- elongate by polymerizing and incorporating more tubulin

Question 23

kinetochore

Answer 23

structure made up of proteins that have assembled on specific sections of DNA at each centromere
- where spindle attaches during prometaphase

Question 24

centrosomes

Answer 24

the of microtubule-organizing center
- aster

Question 25

aster

Answer 25

radial array of short microtubules that extend from each centrosomes during division

Question 26

how many centrioles are in centrosomes in animal cells?

Answer 26

2

Question 27

prophase

Answer 27

• chromosomes (as chromatin) become condensed
• spindle appears between centrosomes
• nucleolus disappears
• centrosomes pushed away from each other

Question 28

prometaphase

Answer 28

• nuclear envelope fragments
• microtubules attach to kinetochores

Question 29

metaphase

Answer 29

• chromosomes arrive at metaphase plate (equidistant between spindle’s poles)
• kinetochore microtubules and nonkinetochore microtubules

Question 30

kinetochore microtubules

Answer 30

jerk chromosomes back and forth, attached to kinetochores

Question 31

nonkinetochore microtubules

Answer 31

interact w/ those from opposite poles of spindle to lengthen cell

Question 32

anaphase

Answer 32

• sister chromatids separate
• chromosomes move to opposite ends of cell

Question 33

telophase

Answer 33

• reversal of prophase
• each cell gets new nuclear envelope

Question 34

cytokinesis

Answer 34

• splitting of cytoplasm through cell plate or cleavage furrow

Question 35

cleavage furrow

Answer 35

• animal cells
• pinches cell in 2
• shallow groove near old metaphase plate
• actin filaments - ring of actin filaments (contractile) on cytoplasmic side, interacts w/ myosin to contract

Question 36

cell plate

Answer 36

• plant cells
• vesicles move along microtubules to middl elf cell and coalesce

Question 37

binary fission

Answer 37

cell grows to double its size then divides
- duplicates of DNA attached to plasma membrane
- used by prokaryotes/bacteria

Question 38

what is another name for mitosis

Answer 38

karyokinesis

Question 39

how many chromosomes present in interphase

Answer 39

46

Question 40

number of chromosomes in each mitotic phase

Answer 40

prophase, prometaphase, metaphase - 46
anaphase - 92
cytokinesis - 46 in each of 2 cells