2.6 Cell Division Flashcards
(37 cards)
cytokinesis
division of cytoplasm → 2 new daughter cell
interphase
phase when cell isnt diving
subdivided into growth/ synthesis phases
mitosis
type of nuclear division
produces genetically identical daughter cells to parent cell
stages in mitosis
- PROPHASE
- nuclear envelope breaks
- chromosomes becomes visible as condenses
( consisted of 2 chromatids)
- centrioles move to poles, causes microtubules to form spindle - METAPHASE
- chromosome line up at equator of spindle, attached to centromere
3.ANAPHASE
- centromere of each pair of chromatid split
- chromatid, pulled apart by microtubules, to opposite poles, centromere first
( –> chromosome)
- TELOPHASE
- nuclear envelope reforms around each set of chromosomes
- separated chromosome reaches poles of spindles, uncoils
- cell contains 2 nuclei( same to parents)
stages in mitosis
- PROPHASE
- nuclear envelope breaks
- chromosomes becomes visible as condenses
( consisted of 2 chromatids)
- centrioles move to poles, causes microtubules to form spindle - METAPHASE
- chromosome line up at equator of spindle, attached to centromere
3.ANAPHASE
- centromere of each pair of chromatid split
- chromatid, pulled apart by microtubules, to opposite poles, centromere first
( –> chromosome)
- TELOPHASE
- nuclear envelope reforms around each set of chromosomes
- separated chromosome reaches poles of spindles, uncoils
- cell contains 2 nuclei( same to parents)
meiosis 1
Prophase 1
- nuclear envelope breaks
- chromosomes becomes visible as condenses
( consisted of 2 chromatids)
- centrioles move to poles, causes microtubules to form spindle
- chromosome comes together in their homologous chromosome form a bivalent
- Crossing over of non-sister chromatic - causes chiasmata to form
→ shuffles allels
Metaphase I
- Bivalent moves to equator of spindles
- Attached to spindle by centromere
- independent assortment of chromosomes
→ random assortment of maternal/ paternal chromosome
Anaphase I
- homologous chromosome are separated back to chromosome, and moved to opposite poles by motor protein
Telophase I
- Nuclear envelope forms around each set of chromosome and uncoils
- Spindles fibers starts breaks
meiosis 2
Prophase 2
- Nuclear envelope breaks
- Chromosomes coils and condenses
- have 2 chromatids, not identical (bc crossing over in prophase 1)
- Spindles form
Metaphase 2
- Chromosome align along equator of spindle
- Attached centromere
- independent assortment of chromatids
→ random assortment of chromatids
→ further distribution of genetic material
Anaphase 2 - Centromere divide - Chromatids of each chromosome are pulled apart toward opposite poles →chromatids segregation - Spindles fibber shorten
Telophase 2
- Nuclear envelope forms around each set of chromosome
- Chromosome uncoils
- Spindles fibber break down
- animal: 2 cell divide → 4 haploid cells
- plant: a tetra of 4 haploid cells
why sexual reproduction involve meosis
- 2 gamate nuclei are going to fuse
- to maintain normal(46) chromosome number, chromosome no in gamates must be halved
- fusion of 2 haploid(n) cell nuclei produces a diploid(2n) nucleus
describe how meiosis produces genetic variation in gametes
- shuffling allele (crossing over in prophase 1)
- independent assortment of chromosomes in metaphase/anaphase 1
- independent assortment of chromatids in metaphase/anaphase 2.
describe how fertilisation produces genetic variation in gametes
The resulting zygote will contain genetic material from two unrelated individuals.
genetic variation good
individual more adapted to change in environment
population survive and
drive evolution
stage of meiosis chromosome no halved
Telophase 1/end of meiosis 1.
product of meiosis
- Four haploid nuclei (cells) that are genetically different from each other and from the parent cell.
stages in cell cycle that DNA replication occurs
interphase, S phase
significance of complementary base pairing during DNA replication
A-T
G-C
ensures proper base incorporated DNA strand
thus making identical copies of DNA strand
meiosis and fertilization give rise to genetic variation
- random arrangement of bivalents/ pair of chromosome
maternal, paternal chromosome could go to either pole
crossing over
exchange of material between homologous chromosomes/ non-sister chromatids
segregation of alleles in meiosis
combination of alleles are broken up
random fertilization
many possible combination of male and female gamtes
exchange of segments of chromatids by breaking and rejoining
crossing over ( prophase)
centrioles
- a pair of organelle in animal cells
- build microtubules to form spindle
cell cycle
interphase, mitosis, cytokinesis
asexual
reproduction no gametes, fertilisation
zygote
produced by fusion of 2 gametes
mitosis
nuclear division produces 2 daughter cell genetically similar to each other/ parent cell
centromere
- where 2 chromatids are held
- where microtubules of spindle attach during cell division
chromatids
1 of 2 identical part of chromosome
