what stages does the cell cycle consist of?
INTERPHASE:
G1 phase
S (synthesis) phase
G2 phase
M (MITOTIC) PHASE
Mitosis
Cytokinesis
G1 phase
- organelles replicate
- transcription/translation
- size of cell increases
S (synthesis) phase
- DNA synthesis
- chromosomes replicate
G2 phase
- energy stores replaced
- transcription/translation
- chromosome repair
- size of cell increases
mitosis
- chromosomes separate into two nuclei
- division of the nucleus
cytokinesis
- cell divides into two
stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
prophase
- chromosomes condense and become visible in nucleus
- each chromosome consists of 2 sister chromatids joined at centromere
- nucleolus disappears
- nuclear membrane starts to break down
- centrioles move to either pole of the cell
- spindle fibres form
metaphase
- spindle apparatus has completely formed
- chromosomes are lined up at equator of the cell
anaphase
- centromeres divide into two
- spindle fibres begin to shorten
- pulling sister chromatids towards opposite poles of the cell
telophase
- chromatids have reached the poles of the cell
- referred as chromosomes
- spindle apparatus breaks down
- nuclear membranes reform
- chromosomes uncoil into chromatin state
- nucleolus reapperas
cytokinesis
- central cell membrane is pulled inwards by cytoskeleton
- eventually membranes fuse, to form tow independent cells
what does the mitotic index indicate?
the ratio between the number of cells in a tissue sample that are in mitosis and the total number of cells in the sample
mitotic index
how can the mitotic index be used to measure the effectiveness of treatments of cancer?
if the treatment is working, the mitotic index of the tumor will fall
haploid
cells with a single set of chromosomes (n)
diploid
cells with two complete sets of chromosomes (2n)
which cells in the human body are haploid?
egg cells (ova) and sperm
how many pairs of autosomes do humans have?
22 pairs of autosomes
how many pairs of sex chromosomes do humans have?
1 pair of sex chromosomes (XX or XY)
how many homologous pairs of chromosomes do women have?
23 pairs
22 pairs of autosomes
1 pair of sex chromosomes XX
what is the name of the opening into the uterus?
cervix
what destroys some of the sperm
the acid environment
what is the name of the outer layer of the egg
corona radiata
