Cell division
2018-06-04 08:42:53 3 举报AI智能生成
细胞分裂
作者其他创作
大纲/内容
Meiosis
Features
DNA replicate once, cell divide twice
germ cells
diploid to haploid
2n = 46 for humans
Interphase before meiosis
Long S phase
incomplete DNA synthesis: 0.1%-0.3% left
heterochromatin (protecting function)
regulatory G2 phase
Meiosis I
prophase I
significantly lengthened comparing to mitosis prophase
leptotene（细线期）
chromosome condense, but two sister chromatids do not separate
子主题
string-like chromomere（染色粒）
telomere connected with nuclear envelope
also called the "bouquet stage"
zygotene（偶线期）
homologous chromosome paring with each other (synapsis，同源染色体联会)
connected by synaptonemal complex（联会复合体）
formation of tetrad（四分体）
0.3% DNA synthesis (zygDNA)
pachytene（粗线期）
chromosome shortened and thickened
DNA crossing-over
at recombination nodules（重组节）
which is part of SC
P-DNA synthesis, which codes enzymes for DNA splicing and repairing
synthesize specific meiotic histones
diplotene（双线期）
SC dissolution, homologous chromosomes repelling
homologous chromosomes connected at chiasma（交叉点）
chiasma maintained by cohesin
灯刷染色体
diakinesis（终变期）
chiasma reduces
nuclear envelope disassemble
formation of meiotic spindle
tetrads move to the metaphase plate
metaphase I
tetrads positioned at metaphase plate
sister chromatids connected with MT from the same pole
anaphase I
separation of homologous chromosomes, moving two both poles
telophase I
chromosomes positioned at poles
chromosomes decondensed, but not fulled dispersed
nuclear envelope may or may not assemble
Meiosis II
similar to mitosis
significance
chromosome number agrees through epochs for organisms
generating inheritable mutations (by homologous chromosomes crossing-over)
sperm generation
发生于曲细精管
ovum generation
出生时卵母细胞停留在减数分裂I前期的终变期
受精后完成减数分裂II
Amitosis
major division method for lower organisms
do not form spindle or chromosome
fast & low energy demand
could cause genetic material distribution inequality
Mitosis
replicated DNA faithfully seperate
prophase
chromatin condensation
cohesin
binds two sister chromatids
condensin
forming a ring within chromatin
formation of mitotic spindle begins
centrosome duplication
growth of daughter centrioles complete in G2
centrosome splits in prophase
the centrosome cycle (of animal cells)
centrosome dysfunction may lead to tumorigenesis
formation of 2 asters begin
asters
centrosome
PCM
aster microtubule
cytoskeleton dissassembly
division polar established
aster begin to move to 2 polars
prometaphase
disassembly of the nuclear envelope
lamin (intermediate filament) phosphorylation
completion of mitotic spindle
mitotic apparatus
kinetochore MT
centromere-kinetochore complex
kinetochore functions
site of attachment of dynamic microtubules
residence of several motor proteins
involved in signaling pathway of mitotic checkpoints
mad & bud protein
astral MT
polar MT
chromosome alignment (at spindle equator)
metaphase
chromosome congression
push hypothesis
repulsion of astral MT
pull hypothesis
traction of kinetochore MT
anaphase
centromere split & chromatids seperate
separase
inactivate by securin & seperase phosphorylation
chromosomes move to spindle poles
anaphase A
kinetochore MT disassemble
spindle poles move farther apart
anaphase B
both push and pull
telophase
chromosome move to each pole and disperse
nuclear envelope assembly
Golgi complex & ER reform
cytokinesis
animal cells
furrow(分裂沟) form to separate cells
called the midbody
middle part of the mitotic spindle induce the furrow
plant cells
Golgi apparatus form new cell wall (cell plate细胞板)
0 条评论
下一页
