ch 23 Flashcards
what are the external events that control the cell cycle? what effect do they have (+/-)?
-death of neighboring cells (+ ) - opens up the space
-growth hormones (-/+)
-crowding (-) - the cells stop dividing if they come in contact with another cell
-cell size (+) - divides to become smaller
what are the internal events that control the cell cycle?
-checkpoints
-regulatory molecules
What protein is responsible for cancer cells? why?
-telomeres since they are abnormally active
-after every replication will replenish itself maintaining its length
why are normal cells limited to a finite life span? when is the protein active?
-since there are a number of divisions that they can live through until the telomeres get to a certain length (caused by the chewing) and will stop dividing
-telomeres are not active in somatic or adult cells only in stem cells and young cells they are
what would happen if the cell did not stop dividing?
-cancer: a disease caused by uncontrollable cell growth caused by an absence of appropriate signals or the presence of inhibitory signals
what are some key characteristics of cancer?
-cytoskeletal change (does not look normal)
-reduced adhesion and increased ability to relocate (move around to different organs)
-reduced differentiation( stays immature by replicating fast and makes a bunch of mistakes)
-immortality
Ability to stimulate blood vessel growth (stimulate the body to grow blood vessels next to the mass creating a highway for it to transport through the body )
what does cancer build up from?
mutations that accumulated which originated from a single cell (we know this because of X-inactivation)
growth factors
-molecules that are released by certain cells that stimulate other cells to do anything (die, divide etc)
steroid and protein-based hormones
–protein can not entire the cell by itself
-steroid can go through the membrane and come in contact with the receptor inside
cell surface proteins
proteins displayed on the cell surface that trigger signal transduction pathways
=receptor for the growth factor and when it is triggered it will cause differential gene expression
what will trigger signal transduction?
-receptor-ligand interactions
=molecules transmitting signals to other molecules
= Eventually the activated protein will enter the nucleus and control gene expression (RAS is a common 1)
what are intracellular signals controlling cell division?
cyclins and cyclin-dependent kinases (CDKs)
cyclins
proteins that fluctuate cyclically in concentration in the cell (not always)
= drivesparts of the cell cycle
cyclin-dependent kinases (CDKs)
these are enzymes in constant concentrations in the growing cell but mostly in the inactive form
-they have to be activated by a cyclin
what are the two types of genes associated with cancer?
proto-oncogenes
tumor suppressor genes
