The Cell Cycle, Mitosis, Meiosis

cell division

creates new cells (1—> 2)

asexual reproduction

creating genetically identical offspring

why is asexual reproduction good but bad as well

quick

problematic with a constantly changing environment

sexual reproduction

creating genetically diverse offspring

binary fission

a type of asexual reproduction

used by many bacteria

creates 2 daughter cells from 1 parent

chromatin

loosely wound DNA (scribbles)

chromosome

tightly wound DNA (half of X)

what is the DNA in a chromosome wrapped around

histone proteins

sister chromation

duplicated chromosome held together at centromere (X)

interphase

all of the cell cycle except M

mitosis

nuclear division that maintains chromosome number

how many chromosomes per human

46

what are the 5 phases of mitosis

prophase

prometaphase

metaphase

anaphase

telophase

what happens in prophase

nucleolus disappears

chromatin condense into chromosomes

separation of centrosomes(centrioles)

formation of spindle fibers

what happens in prometaphase

nuclear envelope disassembles

spindle fibers (microtubules) attach to chromosomes

what happens in metaphase

chromosomes align on the metaphase plane (middle)

what happens in anaphase

chromatids separate towards opposite poles

what happens in telophase

new nuclear envelope forms'

chromosomes unfold back into chromatin

nucleoli reappear

cell continues to enlongate

what is cytokinesis

occurs after mitosis

doesn’t happen to all cells

daughter cells divide

how do plant cells do cell division

form a new cell wall from cell plate

how is a cell plate formed

with vesicles that are lined up

how do animal cells do cell division

they pinch

how do animal cells pinch

they have a cleavage furrow with is a contracting ring of microfilements

what is cancer

uncontrolled cell division

what is a mass of cells called

a tumor

what do most cells need to divide

growth factor (proteins and signals tell them to divide)

why are checkpoints important

to make sure cells are good and correct so they don’t replicate bad cells

what happens if a cell fails a checkpoint

G0 —> try to fix cell—> can’t fix them destroy cell

what is it called whena cell destroys itslef

apoptosis

why is apoptosis good

it prevents cancer and only affects the 1 cell (not like all cells getting damaged)

what do cancer cells do at checkpoints

ignore them

what are the stages of cancer and what do they mean

1- small mass

2- spread in the same area

3+4- spread to other parts of the body

what us it called when cells spread to other parts of the body

metastasis

ploidy

number of sets of chromosomes (not how many chromosomes we have)

haploid

1 set of chromosomes

diploid

2 sets of chromosomes

humans are diploid or haploid

diploid we have 46 chromosomes in 2 sets 1 set from mom and 1 from dad (23 from each)

what is the 23 set of our chromosomes

the sex chromosomes

for every single type of chromosome we have how many sets

2

one of the set of 2 chromosomes is from mom and one from dad

mitosis drawing

Meiosis definition

nuclear division that halves chromosome number

What is the result cell wise of meiosis

it creates 4 haploid cells from 1 diploid cell

haploid shorthand

1n

diploid shorthand

2n

what kind of cells come from meiosis

gametes (sperm and eggs)

what kind of cells are the first cells in meiosis

germ cells

what are germ cells

they are in ovaries and testes and are supposed to make sperm and egg

why don't germ cells just immediately split into four cells

we would run out of germ cells

What do the cells do instead to preserve a germ cell

they preform mitosis (which remember preserves chromosome number)

meiosis drawing

what are the 3 ways meiosis increases genetic diversity

independent assortment, crossing over/genetic recombination, random fertilization

what is independent assortment

how they line up all ways are equally likely because it is random

when does independent assortment occur

metaphase 1

what does the diploid shorthand (2^n) mean/determine

n = sets of chromosomes (for example humans have 23)

so 2^n helps determine the number of different combinations or orders of chromosomes

(humans 2²3 = 8,000,000)

what is crossing over/ genetic recombination

when the 2 chromosomes cross over each other and swap some genes

when does crossing over occur

during Prophase 1

when crossing over what has to match for them to be able to cross over

their number (a 1 to a 1, 2 to a 2, etc)

the area that swaps on a chromosome is called

chiasma

what is random fertalization

sperm and egg are random, random sperm fertilizes random egg

what is nondisjunction

when chromosomes don’t separate correctly

how can nondisjunction occur in meiosis 1

this can happen because of the failure of a pair of homologous chromosomes to separate during meiosis 1 (an entire tetrad moves to one side)

how can nondisjunction occur in meiosis 2

the failure of sister chromatids to separate during meiosis 2

what is affected if the mistake occurs in meiosis 1

it will affect all four gametes (sperm or egg)

what is affected of the mistake occurs in meiosis 2

only 2 gametes will be affected

what is a karyotype

a picture of someones chromosomes (a photographic inventory of an individual’s chromosomes)

what are a males sex chromosomes

XY (y is a lot smaller in general)

what are a females sex chromosomes

XX

whta is it called when there is an extra copy of chromosomes 21

down syndrome (trisomy 21)

what is a survival rate of trisomy 21

it is high

do other chromosome number differences usually survive

no

is this a mutation

no a mutation is a change in DNA

what is the biggest risk factor for having a child with trisomy 21

a woman’s age

why is a woman’s age a big risk factor

nondisjunction increases as you age

what is the affect of an abnormal number of sex chromosomes

not usually any affects

doesn’t usually affect survival

but could

health issues sometimes come with what chromosomes (what may be the issue and name)

XXY

Klinefelter syndrome (male)

sterile

usually normal with what chromosomes

XXX (maybe slightly taller than average)

what are autosomes

chromosomes that aren’t the sex chromosomes

what is turner syndrome and what are the symptoms

when only one X chromosome is received (X0)

female

sterile

what is a somatic cell

a cell that is not a gamete, germ , etc cell

what is the cell cycle

G1

S

G2

M

what occurs in G1

growth

what occurs in S

DNA replication

what occurs in G2

growth and prep for mitosis

what is M

mitosis

do cells that do meiosis do the cell cycle

kinda they grow, and they replicate their DNA in the first stage of meiosis

when meiosis 1 is finished what are the 2 cells that are made

haploid