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biology ch cell growth and division

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why are cells so small
messages from the nucleous must be able to reach all parts of the cell
if the cell was too big, diffusion would happen too slowly
a bigger call needs more nutrients but has relatively less surface area to take in nurtients
surface area vs volume
surface area- 1w6
volume- 1wh
cell cycle
the life of a cell from the end of one cell division to the end of the next cell division
Go phase
cells dont divide again
interphase
preparation
G1 phase
gap one or growth one- cells grow
s phase
synthesis- replicating the organnelles for the daughter cells to have
G2
gap two or growth two
chromatid
condensed form - X - connected by a centromere - they are identical chromosomes
chromatin
uncondensed form- (crazy strands)
stages of mitosis
prophase---first
metaphase--middle
anphase---part
telephase---away
prophase
chromosones codense from chromotin to chromotids
nuclear envelope starts to disspear
centorioles start going to the ends of the cell and spindle fibers form
metaphase
chrmosones line up in the middle of the cell and spindle fibers attach to the centrimere
anaphase
sister chromotids are pulled apart
spindle fibers pull the chromotids to opposite ends of cell
animal cells have cleavage furrow
plant cellls begin to form a cell plate
telaphase
nuclear envelope built from ER around each set of chromosones nucleus reforms
chrmosones become chromatin
cytokinesis
final division of cytoplasm so there is two separate cells
animals-cell membrane pnches off
plants- cell plate forms new cell membrane dividing the daughter cells
cyclins
proteins that regulate the cell cycle in eukaryotes
internal regulations
regulate process so there is no mistakes
only lets the cycle begin when other cycles are done
external regulations
tells it to divide or stop divding chemical
messages from another nucleus
cancer
too many cells dividing and building up and cells dont respond to cell cycle regulators
tumor
cells growing unregulated