Cell Cycle Flashcards
Interphase
period between mitotic divisions
G1
S
G2
18-24 hours in lab cells
Mitosis
cell division that produces 2 cells
usually less than 1 hour in lab cells
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
cleavage furrow forms and deepens
cytoplasmic division
Stages of cell cycle
interphase
mitosis
cytokinesis
G0
inactive stage between cytokinesis and G1
white blood cells enter G0, later reenter G1, and divide
G1
immediately after mitosis
cell growth BEFORE DNA replication
production of cytoplasmic components like organelles, ribosomes, membranes, RNA
cell size doubles
S (synthesis)
DNA replication = chromosomes duplicated
sister chromatids form
G2
cell becomes ready to divide
mitochondria divide
precursors of spindle fibers synthesized
Prophase
PREPARE
chromosomes condense and become visible
nuclear envelope disappears
centrioles divide, migrate to opposite poles of cell
spindle fibers form and attach to chromosomes, stretch across the cell
Metaphase
chromosomes line up on the MIDDLE of cell
46 centromeres, each attached to 2 sister chromatids
Anaphase
APART
chromosomes begin to separate
each sister chromatid is converted into a chromosome
briefest stage, but ensures each cell receives an identical set of 46 chromosomes.
Telophase
chromosomes reach opposite poles and decondense
spindle fibers break down
new nuclear envelope forms
mitosis is completed
Meiosis
one cycle of chromosomal replication followed by 2 successive cell divisions = 4 haploid cells
homologous chromosomes
Reduction division
chromosome number reduced to half (46 to 23, diploid to haploid)
meiosis I
Prophase I of Meiosis
each chromosome pairs with its homologue
crossing over
spindle microtubules attach to each chromosome
Metaphase I of Meiosis
chromosomes and spindle poles move apart, into position midway between poles
Anaphase I of Meiosis
homologous partners move to opposite poles
Telophase I of Meiosis
cytoplasmic divison to produce 2 haploid cells, with one of each chromosome type
chromosomes are still in the DUPLICATED state
Prophase II of Meiosis
microtubules attach to the chromosomes
Interkinesis (Meiosis)
no DNA replication between two nuclear divisions
Metaphase II of Meiosis
duplicated chromosomes positioned midway between the two poles
Anaphase II of Meiosis
sister chromatids of each chromosome move to opposite spindle poles
each ‘sister’ chromatid is now a chromosome
Telophase II of Meiosis
4 haploid daughter nuclei produced
all chromosomes are now in the unduplicated state.
Spermatogenesis
primary spermatocytes enter meiosis
after meiosis i = secondary spermatocytes
after meiosis ii = haploid spermatids, undergo changes and become mature sperm
Oogenesis
primary oocytes enter meiosis during embryonic development, arrest in meiosis i
one oocyte per menstrual cycle completes meiosis i just before ovulation
haploid secondary oocyte is formed, along with a polar body (nonfunctional)
if secondary oocyte is fertilized, meiosis is completed (sperm stimulates meiosis ii)
