cell division

Question 1

uses of cell division

Answer 1

unicelular organisms: reproduction
multicel. org.:
growth, repair, reproduction

Question 2

how many and what type of chromosomes do prokaryotes have

Answer 2

1

circular

Question 3

what’s the name of cell division done by prokaryotes

explain process

Answer 3

(bacteria+archea) do binary fission (2 exact copies of one)

• dna replicases and cell wall grows
• DNA gets pulled apart and cell separates

Question 4

what 2 types of cell division do eukaryotes do + explain their use

Answer 4

Mitosis: dividing somatic (not sex) cell
ex: growing, repairing cuts, replace old cells

Meiosis: division of germ (sex) cells-> it produces gametes that are different from the parents and the siblings
ex:eggs/sperm production

Question 5

the phases of mitotic cell cycle

Answer 5

interphase 
mitosis (m phase)

Question 6

explain interphase

Answer 6

(90% of the time its interphase)
G1: cell growth + maintenance towards end is restriction point: have to continue and replicate DNA/divide because surface area/volume is unbalanced
S phase (synthesis):dna replication (1 chromosome->2 chromatids)
G2:cell grows + prep for mitosis (*2 centrosomes, etc)

Question 7

stages of M phase (mitosis)

Answer 7

prophase 
prometaphase
metaphase
anaphase
telophase

Question 8

what is cytokinesis and when can it happen

Answer 8

division of cytoplasms

can happen after mitosis, after nuclear division

Question 9

how is chromatin made

Answer 9

DNA wound around histone protein this is called a nucleosome

Question 10

what is a eukaryotic chromosome

Answer 10

a strand of chromatin

tightly wrapped

Question 11

describe s phase

Answer 11

helix unwinds and complementary base pairing is done with each strand

Question 12

what are sister chromatids

when is it there

Answer 12

its the 1 chromosome that is now 2 identical strands held together at centromere
it is there as soon as mitosis starts also there but looser in s phase and not visible as an x

Question 13

everything about centrosomes
what?
what do they do and when?

Answer 13

made of 2 centrioles at 90º angles
at G2-M they move to opposite ends of cell
cause formation microtubules which leads to spindle structure (like claws to drag one chromosome to one side and one to the other (look it up))

Question 14

prophase

Answer 14

• chromosomes condense ( x (paired chromatids) visible)

- kinetochore (ring of protein forms in centromere area of each chromosome )

Question 15

what are the types of microtubules in the spindle

Answer 15

• polar microtubules: spindle sturcture/ track

- kinetochore microtubule: connects to kinetochore of chromosome and pulls the sisters away.

Question 16

prometaphase

Answer 16

nuclear envelope and nucleus disappear

chromosomes slowly are pushed to middle of the cell

kinetochore microtubule approach and attach them to the poles

Question 17

metaphase

Answer 17

chromosomes are in middle of cell (called equatorial plate)

at end of this phase centromeres (holding chromatid pairs together) seperate

Question 18

anaphase

Answer 18

the pairs of chromatids (daughter chromosomes) go on microtubule track to the poles

Question 19

telophase

Answer 19

spindle breaks down
chromosomes uncoil and are less condensed
nuclear envelopes and nucleoli reform,

Question 20

how does cytokinesis happen in animals

what’s it called

Answer 20

contraction of cytoplasmic microfilaments, it separates the cytoplasms of 2 daughter cells

plasma membrane furrowing/ cleavage

Question 21

how does cytokinesis happen in plants

Answer 21

vesicle fusion forming the cell plate (new cell wall)

Question 22

what type of reproduction is mitosis, who uses it?

Answer 22

asexual reproduction

unicellular org. reproducing or multicell org. breaks off to from new individual

Question 23

how could there be genetic variety in mitosis

Answer 23

mutations

because theyre clones

Question 24

what are somatic cells

Answer 24

2n diploid (2 sets of chromosomes) 
not for reproduction 

they hav homologous pairs of chromosomes with the corresponding gene (=size,shape, info)

each parent gives one homolog

Question 25

what are gametes

Answer 25

sperm/egg

• haploid n (one set of chromo) for reproduction
• half of the parents chromo are randomly taken, every kid will be different)

Question 26

what is it when 2 gametes (boy+girl) meat and fuse to form diploid zygote cell

Answer 26

fertilization

Question 27

name the sexual life cyckes

Answer 27

haplontic life cycle
alternation of generations
diplontic life cycle

Question 28

what is haplontic life cycle

Answer 28

a sexual life cycle
fungus/protist use it
zygote is only 2n stage

Question 29

what is alteration of generations

Answer 29

sexual life cycle
plants and photosythetic protist
meiosis makes n spores

1/2 haploid 1/2 diploid

Question 30

what is diplontic life cycle

Answer 30

sexual life cycle
animals use it
gametes are only n stage

Question 31

how Many times does the meiosis do nuclear /? and y?

Answer 31

2 times

to make chromosomes haploid

Question 32

prophase 1 (meiosis)

Answer 32

homologous chromosomes pair up

material is exchanged cy crossing over (recombination) between non sister chromatids of adjacent homologs

Question 33

what follows telophase 1 in meiosis

Answer 33

interkinesis (its its interphase)

DNA can replicate now

Question 34

how many cells are made from meiosis

Answer 34

4

Question 35

what is nondisjunction

Answer 35

one homologous pair of chromosmes dont separate from each other and both go to same pole (mitosis 1)
OR sister chromatids dont separate (mitosis 2)

Question 36

what are the effects when nondisjunction occurs

Answer 36

one gamete has and extra chromosome -> trisomy

one gamete is lacking a chromosome -> monosomy

if fertilized with normal gamete it crates aneuploidy

Question 37

karyotype

Answer 37

the number, shapes, and sizes of the chromosomes in a cell

Question 38

how to recognize individual chromosomes from each other

Answer 38

LENGTHS, POSISITON OF CENTROMERE BANDING PATTERNS