Chapter 29 - Cell Cycle Regulation and Cancer

stem cells

retain the ability to divide

what are the main checkpoints that have “stop/go” signals?

G₁, M, G₂

G₁ checkpoint

looks for correct size, the availability of nutrients, and any damage to DNA

M checkpoint

ensure that chromosomes are aligned in the center of the cell

oncogenes

the “go” signal

when do oncogenes cause cancer?

they can be too strong and override the stop signal

tumor suppressor genes

the “stop” signal

when do tumor suppressor genes cause cancer?

they can be too weak and cause masses to form

tumor

a mass of cancer cells

benign

slower growing and less expansive/invasive

malignant

rapidly grows, very invasive

ras gene

initiate pathway even in the absence of needed factors

p53

let cells with damaged DNA to go through cell division

telomeres

when a portion is lost the chromosome shortens at each division, stops division once a certain amount is lost

telomerase

rebuilds telomeres, stem cells use this enzyme to keep dividing

contact inhibition

division stops when cells have too much contact

anchorage dependence

only divides when in contact with other cells

MPF

made of the buildup of cyclins and CDK