Lecture 10 - Cell Cycle and Cytokinesis Flashcards
what are histones?
alkaline proteins which DNA is coiled around to form chromosomes they order DNA to form nucleosomes
what are somatic cells?
all body cells except sperm and egg cells
what is apoptosis?
programmed and targeted cell death
what is necrosis?
death of all cells or most cells in an organ or tissue
what is cell death controlled by?
controlled by suicide gene activation
what is atrophy?
rate of death of cells is higher than cell formation (proliferation)
what is dysplasia?
increased proliferation and decreased apoptosis
Describe interphase
cell grows ands prepares for division contains G1, s and G2 junctions/ phases
what is the G1 phase?
does not pass without growth factors, 8-10 hours of cycle, protein synthesis and centrosome replication begins
what is the s phase?
8 hours, DNA replicates catalysed by DNA polymerase + helicase, forms origin Y shape called the replication fork
what is G2 phase?
4-6 hours, synthesis of enzymes and proteins essential for division, replication of centrioles
what is the mytotic phase?
contains karyokinesis and cytokinesis
what is karyokinesis?
division of the nucleus
what is the cleavage furrow?
gap between the two cells splitting
what is G0 phase?
resting period in the cell cycle, cell grows and divides and programmed cell death occurs
what are cyclin dependent kinases?
regulate the initiation of cell growth, cell cycle is switched on and off by cyclins
what is the checkpoint in G1 phase?
restriction point, cells that should cease division exit the cell cycle and enter G0, cells that continually divide have to overcome the restriction check point
where are what is the second checkpoint?
at the end of G2 phase, triggering the start of mytotic phase
what is the reason for checkpoints?
checkpoints are guardians of the genome, cancer cells can override the checkpoints and cyclin kinases have to be turned off without these check points cancer would be more apparent due to multiple genetic mutations
