Cell Cycle Flashcards
meiosis
special 2-stage type of cell division in which 1 diploid (2n) parent cell produces haploid (n) cells (gamates)
- result: halving chromosome #
- sexually reproduction
- leads to production of gamates (sperm & eggs)
- daughter cells have half the amount of hereditary material as parent cell
Mei -> gamates
mitosis
process of nuclear division in which 2 daughter nuclei are genetically identical to the parent nucleus
- cytokinesis leads to 2 identical daughter cells
- lead to production of all other types of cells (somatic cells)
- cellular replication
mit -> somatic/other cells
phases of cell cycle
(1) M phase
(2) Interphase
interphase
portion of cell cycle btwn one M phase and the next
- DNA replication occurs here
- uncondensed chromatin
(1) G1 phase
(2) S phase
(3) G2 phase
*most cells spend their time here (not dividing stage - G1 phase)
M phase
2nd step of cell cycle
- cell division occurs here
- replicated chromosome condense
- sister chromatids separate
- 2 daughter cells formed by cytokinesis
division of nucleus & cytoplasm
M phase = PPMAT
G1 phase
1st step of interphase in cell cycle
- 4 unreplicated chromosomes
- non-dividing cells stuck here
- allow parent cell to grow large enough to divide into 2 cells that will fcn normally
growth phase
S phase
2nd step of interphase in cell cycle
- DNA synthesis (break down)
- chromosome replicated
“synthetic phase”
G2 phase
3rd step of interphase in cell cycle
- 4 unreplicated chromosomes
- sister chromatids
growth phase
gamate
haploid (n) reproductive cell
- can fuse w/ another haploid cell to form a zygote
(ie) eggs & sperm & precursor cells
gene
a section of DNA (RNA for some viruses)
- encodes info for building related polypeptides or fcnal RNA molecules along w/ regulatory sequences required for its transcription
deoxyribonucleic acid (DNA)
nucleic acid composed of deoxyribonucleotides
- double helix structure
- encodes cells’ hereditary info or genetic material
chromatid
1 of 2 identical double-stranded DNA composing a replicated chromosome
- sister chromatids connected @ centromere
number of chromosomes in human somatic cell
46 chromosomes
(23 chromosome pairs)
2n
cell cycle checkpoints
critical point in cell cycle in which cell progression is regulated
- G1 checkpoint
- G2 checkpoint
- M phase checkpoint
no pass checkpoint, cannot proceed onward
“is this ready?”
G2 checkpoint
(1) chromosomes must have replicated successfully
(2) no DNA damage
(3) MPF activated & present
G1 checkpoint
(1) adequate cell size
(2) sufficient supply of nutrients
(3) social signals present
(4) no DNA damage
M phase checkpoint
(1) chromosomes attached to spindles
(2) chromosomes properly segregated
(3) MPF absent
cytokinesis
cytoplasm divides to form 2 daughter cells
- occurs after M phase
cell divides
actin-myosin pinch plasma membrane
cytoskeleton roles during mitosis
(1) architectural framework cells can organize subcell organelles & metabolic machinery
(2) cell shape
(3) cell movement
(4) cell division
cyotoskeleton - cell shape
cytoskeleton determines cell shape (intermediate filaments)
cytoskelton - cell movement
microfilaments + microtubules assemble & dissemble to move cell
cytoskeleton - cell division
microtubules move chromosomes to daughter nucleus
kinase
enzyme that catalyzes transfer of phosphate group from ATP to a target protein
- subunit of MPF
- always present
cyclin-dependent kinase (Cdk)
protein related to kinase
- fcnal when bound to cyclin
- activated by other modifications
- regulates other proteins & cell cycle