cell growth and division depend on
protein signals & other environmental signals & checkpoints
protein signals
many proteins within the cell control the phases of the cell cycle
other environmental signals
signals from surrounding cells/even from other organs can also regulate cell growth and division
environmental conditions, including availability of nutrients, also affect the cell cycle
during the cell cycle-
a cell undergoes an inspection process to ensure that the cell is ready for the next phase in the cell cycle
feedback signals at key checkpoints in the cycle can
delay or trigger next phase of the cell cycle
three main checkpoints in the cell cycle
G1 checkpoint
G2 Checkpoint
mitosis checkpoint
G1 checkpoint
before the cell copies its DNA, the cell checks its surroundings
if conditions are favorable and the cell is healthy and large enough-- the cell enters SYNTHESIS PHASE
if conditions are NOT favorable- the cell goes into a RESTING period
certain cells, suc
G2 checkpoint
before mitosis begins, the cell checks for any mistakes in the copied DNA. enzymes correct any mistakes.
this checkpoint ensures daughter cells DNA will be identical to the DNA of the og cell
PROTEINS also double check that the cell is LARGE ENOUGH to div
mitosis checkpoint
during the METAPHASE stage of mitosis, chromosomes line up at the equator.
at this point- the cell checks that the chromosomes are properly attached to the spindle fibers (u good)
w/o dis- sista chromatids of 1+ chromosomes might not separate properly.
th
CANCER
each year, more than 1 million Americans are diagnosed with cancer :(
def: a group of severe and sometimes fatal diseases that are caused by UNCONTROLLED cell growth
uncontrolled cell growth and division can result in masses of cells that invade and DESTR
loss of controlll
normally- a cell responds properly to signals and controls
but- damage to cell's DNA can cause the cell to respond improperly/stop responding-- leaving the cell cycle UNCONTROLLED
the defective cell divides and produces more defective cells. eventually- t
benign tumor (development)
benign tumor- does NOT spread to other parts of the body and can often be removed by SURGERY
malignant tumor (development)
invades and destroys nearby healthy tissues and organs
(cancers)
can break loose from their tissue of origin and grow throughout the body- METASTASIS
once cancer has metastasized- hard to treat
metastasis
malignant tumors, or cancers, can break loose from their tissue of origin and grow throughout the body
treatment
some cancers can be treated by using drugs that kill FAST GROWING CANCER cells
bc drugs ARE chemicals-^ called CHEMOTHERAPY (aka chemo 4 short)
some cancers can be treated by SURGERY to remove of the affected organ
in RADIATION therapy- high energy rays a
chemo
using drugs that kill FAST GROWING CANCER cells
radiation therapy
high energy rays are focused on an area to DESTROY cancer cells
prevention
best way to prevent cancer is to avoid things that can cause cancer (duh)
Ultraviolet radiation (UV rays) in sunlight can damage genes that control the cell cycle
chemicals in cigarette smoke - can also affect how cell growth & division is regulated
IN SHORT ...
cell growth and division depend on protein SIGNALS & other environmental signals
feedback signals @ key checkpoints in the cell cycle can DELAY/TRIGGER next phase of the cell cycle
uncontrolled cell growth and division results in TUMORS- can invade surrou