ch10: how cells divide

Question 1

what does cell division produce

Answer 1

two genetically identical cells

Question 2

two keys to cell division

Answer 2

1. accurate replication of DNA
2. distribution into daughter cells

Question 3

single celled (prokaryotes) organisms use cell division to

Answer 3

reproduce (binary fusion) (has less DNA, one circular chromosome called nucleoid)

Question 4

multicellular organisms (eukaryotes) use cell division for

Answer 4

growth (to maintain tissues)

Question 5

how many pairs of chromosomes do a human cell have

Answer 5

23 pairs, 46 chromatids

Question 6

core of proteins that DNA strand is wrapped repeatedly around

Answer 6

histones

Question 7

DNA wrapped around histones

Answer 7

nucleosomes

Question 8

DNA is coiled into —— even when cell is not actively dividing (all of interphase)

Answer 8

chromatin; not organized, no structure

Question 9

DNA is further packaged into —– during cell division (all of mitosis)

Answer 9

chromosomes; organized and structured

Question 10

condensation

Answer 10

tight compaction of DNA into chromosomes

Question 11

why does DNA only condense into chromosomes during cell division

Answer 11

it needs to sort individual chromosomes to each daughter cell without getting tangled up

Question 12

during interphase, chromosomes unfold into chromatin because

Answer 12

you need to access the DNA for cell functions (G1, G2, make proteins, etc) and to replicate DNA strands during S phase

Question 13

germ cells

Answer 13

gametes, sperm, egg (singular)

Question 14

germ cells have —- of each chromosome

Answer 14

1 copy (n, haploid)

Question 15

somatic cells

Answer 15

non-reproductive cells; all cells except sperm and egg

Question 16

somatic cells have —- of each chromosome

Answer 16

2 copies (2n, diploid); two homologues for each chromosome

Question 17

how many individual chromosomes are found in a somatic (2n) human cell

Answer 17

46

Question 18

if you see 6 total chromosomes in a somatic animal cell, what is its N number of chromosomes

Answer 18

3n

Question 19

homologous chromosomes

Answer 19

maternal and paternal copies of same chromosome

Question 20

sister chromatids

Answer 20

two replicas of a singular chromosome (after DNA replication in S phase) held together at centromere by cohesin proteins at the kinetochore of the centromere

Question 21

two major phases of the cell cycle

Answer 21

interphase (normal growth and preparation for cell division; G1, G2, S phase)
and mitotic phase (replicated DNA and cytoplasm are split and cell divides; mitosis)

Question 22

stage one of interphase- G1 phase (first gap)

Answer 22

cell is biochemically active, accumulating the building blocks for DNA and protein synthesis

Question 23

G0 phase (gap 0)

Answer 23

cell is in a resting state (not actively replicating)

Question 24

stage two of interphase- S phase (DNA synthesis)

Answer 24

DNA is replicated, centrosome is duplicated (forms the mitotic spindle)

Question 25

third phase of interphase- G2 phase (second gap)

Answer 25

more synthesis, organelles duplicated, cell is preparing for mitosis

Question 26

first phase of mitotic phase- prophase (five bullet points)

Answer 26

-nuclear envelope breaks down
-cetrosomes begin migration to poles
-organelles disperse toward edges of the cell
-DNA condenses into chromosomes
-microtubules of the spindle form, and attach to the kinetochore at the centromere of the chromatids

Question 27

second phase of mitotic phase- metaphase (two bullet points)

Answer 27

-chromosomes line up along metaphase plate
-sister chromatids remain attached by cohesion proteins

Question 28

third phase of mitotic phase- anaphase (two bullet points)

Answer 28

-cohesion proteins degrade, allowing chromatids to separate
-separated sister chromatids move in opposite directions

Question 29

fourth phase of mitotic phase- telophase (two bullet points)

Answer 29

-chromosomes reach opposite poles and begin to decondense (unravel)
-nuclear envelopes begins to form around the chromsomes

Question 30

kineatochores

Answer 30

proteins that connect each sister chromatid to spindle microtubules

Question 31

cohesin (protein)

Answer 31

a protein that attaches sister chromatids together

Question 32

how are sister chromatids properly distributed during mitosis

Answer 32

• during metaphase, microtubules pull on sister chromatid kinetochores, but cohesin keeps them together
• during anaphase, cohesin is destroyed and the sister chromatids are pulled apart