Cell Division

Question 1

how many chromosomes in humans?

Answer 1

46 chromosomes (23 homologous pairs)

Question 2

what does a centrosome contain?

Answer 2

pair of centrioles

Question 3

centrioles

Answer 3

produce spindle fibers that separate sister chromatids during anaphase

Question 4

regulation of cell cycle

Answer 4

• surface-volume ratio
• genome-volume ratio

Question 5

surface-volume ratio

Answer 5

if the volume ratio is small when cell is too big it makes cell exchange hard leading to cell death/division to increases surface area

Question 6

genome-volume ratio

Answer 6

if it decreases, the cell exceeds ability of its genome to produce proteins needed to regulate the cell

Question 7

cell cycle

Answer 7

interphases consiting of G1, S, G2 phase

Question 8

when does interphase occur?

Answer 8

after mitosis and cytokinesis

Question 9

G1

Answer 9

cell increases in size and G1 checkpoint ensures everything is ready for DNA synthesis

Question 10

where does most cell growth occur?

Answer 10

G1 phase

Question 11

S phase

Answer 11

DNA synthesis; 2nd molecule of DNA replicated from 1st into sister chromatids

Question 12

where is DNA replicated?

Answer 12

S phase

Question 13

G2 phase

Answer 13

rapid cell growth; preparation of genetic material for cell division, cell replicates organelles

Question 14

G0 phase

Answer 14

inactive state of cells not actively growing/dividing
- nerve and & cardiac cells

Question 15

when does the spindle apparatus form?

Answer 15

during prophase

Question 16

what does each sister chromatid have?

Answer 16

kinetochore

Question 17

where does kinetochore attach

Answer 17

MT attach’ MT don’t directly attach to chromosomes

Question 18

prophase chromosomes/chromatids

Answer 18

46 chromosomes
92 chormatids

Question 19

metaphase chromosomes/chromatids

Answer 19

46 chromosomes
92 chromatids

Question 20

anaphase chromosomes/chromatids

Answer 20

92 chromosomes
92 chromatids

Question 21

telophase chromosomes/chromatids

Answer 21

92 chromosomes
92 chromatids

Question 22

cytokinesis chromosomes/chromatids

Answer 22

46 chromosomes
46 chromatids

Question 23

prophase

Answer 23

• nuclelus disassembles, nucleoulus disappears
• chromatin condenses into chromosomes

Question 24

metaphase

Answer 24

• chromosomes line up
• each metaphase chromosome consists of 2 attached chromosomes
• each chromatid complete with centromere and attached kinetochore

Question 25

anaphase

Answer 25

* MT shorten and each chromosome is pulled apart into 2 chromatids * chromatids pulled to opposite poles **disjunction** * at the end each pole has a complete set of chromosomes

Question 26

telophase

Answer 26

* nuclear envelope reforms * chromosomes decondense back into chromatin and nucleoli reappear

Question 27

meiosis

Answer 27

produces 4, non-identical haploid daughter cells from one diploid parent cell * does this by repeating nuclear division twice

Question 28

meiosis 1

Answer 28

homologous chromosomes separate

Question 29

prophase 1 chromosomes/chromatids

Answer 29

46 chromosomes 92 chromatids

Question 30

prophase 1

Answer 30

* spindle forms, nuclear envelope breaks down * chromosomes pair up lengthwise through **synapsis** forming tetrads to allow for crossing over * pairs linked with chiasmata * MT attache to chromosomes at kinetochore and move them towards metaphase plate

Question 31

chiasmata

Answer 31

regions where crossing over occurs

Question 32

metaphase 1 chromosomes/chromatids

Answer 32

46 chromosomes 92 chromatids

Question 33

metaphase 1

Answer 33

* homologous chromosomes arranged at metaphase plate * independent assortment of chromosomes occur because arrangement is random

Question 34

anaphase 1 chromosomes/chromatids

Answer 34

46 chromosomes 92 chromatids

Question 35

anaphase 1

Answer 35

homologous chromosomes separate and spindle apparatus guides to opposite poles

Question 36

telophase and cytokinesis chromosomes/chromatids

Answer 36

46 chromosomes 92 chromatids

Question 37

telophase 1

Answer 37

* homologous chromosomes are separates from each other to each end of cell

Question 38

cytokinesis 1

Answer 38

2 haploid daughter cells containing one chromosome for every homologous pair

Question 39

meiosis II

Answer 39

sister chromatids separate

Question 40

prophase ll chromosomes/chromatids

Answer 40

23 chromosomes 46 chromatids

Question 41

prophase ll

Answer 41

spindle apparatus forms and MT move chromosomes towards metaphase plate

Question 42

metaphase ll chromosomes/chromatids

Answer 42

23 chromosomes 46 chromatids

Question 43

metaphase ll

Answer 43

* sister chromatids no longer genetically identical due to crossing over * chromosomes lined up at metaphase plate

Question 44

anaphase ll chromosomes/chromatids

Answer 44

46 chromosomes 46 chromatids

Question 45

anaphase ll

Answer 45

* chromatids separate, move toward opposite poles * separated chromatids now chromosomes

Question 46

telophase ll and cytokinesis chromosomes/chromatids

Answer 46

46 chromosomes 46 chromatids

Question 47

telophase ll

Answer 47

* nuclei formation and decondensing of chromosomes * result is **4** genetically distinct daughter cells

Question 48

sources of genetic variation

Answer 48

* crossing over * independent assortment * random joining of gametes

Question 49

crossing over

Answer 49

non sister chromatids of 2 homologous chromosomes exchange genetifc material during prophase l

Question 50

independent assortment

Answer 50

during metaphase l, random orientation of chromosomes allows for production of gametes with diff. assortment of alleles

Question 51

genetic linkage

Answer 51

gene closer on chromosome more likely to be inherited together