Unit A - mitosis/meiosis Flashcards
the cell cycle
process of cell growth leading up to division
interphase
state imbetween cell division, not actively dividing
mitosis
cell division through the nucleaus
-duplication/seperation of chromosomes
-duplication of nuclei
smaller sections of interphase
Gzero, S phase, G2, mitosis
Gzero
cell growth
-nutrient sufficent?
-chromatin
S phase
replication of genetic material (DNA)
-chromatin/chromosomes
s phase stands for
synthesis phase
G2
last minute checks, more growth
phases of mitosis
prophase (first formal step), metaphase, anaphase, telaphase
prophase
-nucleaus condenses
-last half an hour to an hour
-nuclear envelope begins to disappear
-centrioles move to opposite sides of nucleaus
-astral rays form spindal fibers
“preparation for mitosis”
metaphase
-spindle fibers stretch out throughout cell
-line up at metaphase plate
-best time for karyotyping
anaphase
chromisomes pull apart
-spindle fibers pull apart sister chromatids at centromere
telophase
end of mitosis, starts to physically seperate the cells
cytokinesis
creation of a new cell, spliting of cytoplasm
-organelles are all present, and in seperate spots
-seperation forms in the center, sinching/pinching
-produces two daughter cells
apoptosis
programmed cell death
apoptosis in toes/fingers
when humans are being formed, the skin cells between their toes and fingers have to go through apoptosis
sexual reproduction (cellular level)
combination of haploid cells into diploid cell
n+n = 2n
asexual reproducyion (cellular level)
an exact copy of a cell, to create two identical ‘daughter cells’
daughter cell
cells that are the result of a single dividing cell
asexual reproduction is
mitosis
sexual reproduction is
meiosis
diploid
two complete sets of chromosomes
-after fertilization
haploid
single set of chromsomes in an organism
example - egg cells and sperm cells
half of cells (chromosomes)
examples of mitosis reproduction
-bacteria (binary fusion)
-yeast
-spores
importance of sexual reproduction
creates variation (evolutionary advantages)
purpose of cell division
-growth of an organism
-tissue repair/replacement
-reproduction
chromatin
long linear strands of DNA and proteins, de-condensed form of DNA
chromosomes
DNA and associated protiens, densed into thick rods
-more efficent division and transport
histones
protiens on spools of DNA
-sites for DNA to wrap around, easier to transport
-what makes a chromatin, a chromosome
super coiling
wraping around histones to create rod shapes
centromere
point in the middle of an x chromosome
-attachment point for other proteins during cell division
-spindle fibers grab onto
nucleaur envelope
protection for the DNA inside the nucleaus
G1 leads to
-continuing cell cycle, so s phase
-enter Gzero (can be permanent or reversible)
example of permanent Gzero
neurons (most)
reversible quiescence
-upon certain stimulance, cells can re-enter the cycle
example : immune cells
late interphase
-DNA/organelle replication has occured, chromosome form
-centrioles divided, begining to move apart
centrioles
found perpendicular
-important proteins in the cell
astral rays
help to move around centrioles and form spindal fibers (microtubules)
microtubules
major part of cytoskeleton, help maintain shape of cell
spindal fibers purpose in mitosis
grab onto chromosomes to pull them apart
kinetochore region
where the spindle fibers grab onto chromosomes
chromatids
when chromosomes are split, single chromosome
metaphase plate
cells equator, where the spindle fibers pull apart for even splitting
karyotyping
pairing and ordering all chromosomes in an organism
centromere
center of the chromosome
sister chromatid
chromosome in pair format
nondisjunction
if sister chromatids don’t seperate
telophase (early)
-fibers are pulling, the cell begins to stretch
-cell takes on football shape
-where center fiber meets, they push against fibers to continually pull cell apart
telophase (late)
-two seperate ‘packages’ have formed
-nucleaus (two on either side) begins to reform
-spindle fibers disappear
-chromosomes unwind into chromatin
cleavage furow
-middle portion of cell in cytokinisis (where it splits)
microfilaments form contachie ring, which pinches cells into two halfs
difference between plant cell and animal cell
plant cells have cell wall AND cell membrane
-cell organelles near cleavage furrow harden to produce cell walls for daughter cells
golgi purpsoe in the plant cell
brings polysaccharides for cell wall growth
cloning
taking an organisms information putting it into a surrogates organism, then developing the surrogate into a clone
DNA lives in the
nucleaus
somatic
body cell
egg cell donor steps
remove the egg cell, take only the empty cell (get rid of the nucleaus) fuse cell
nucleus donor
take certain cell, remove nucleaus to be infused with empty egg cell
biological definition of clones
identical DNA information
what organism is the clone identical too?
donated nucleaus organism
NOT the surrogate organism
how long can cells live
120 days to 30 years
at what age is there no cells left to divide in a human
115
once cells specialize/differenciate what happens..
thier ability to divide is reduced
what cells ignore the aging rule
spermatocytes and cancer cells
telomeres
‘caps’ on the end of DNA
-space for the end of DNA to fill
-vitalroleinprotectingthedna
what phase does chromatin exist
interphase and late telophase
what phase does chromosome first exist
prophase
when does DNA duplicate itself
interphase
chromatid vs chromatin
chromatid - one side of a identical pair of chromosome
chromatin - unbound spool of DNA that will eventually wind into a chromosome
three main purposes of mitotic cell division
growth, repair, asexual reproduction
what is in the cell during interphase
nucleus, chromatin (duplicated), centrosomes (with pair of centrioles)
what is in the cell during prophase
early mitotic spindle, aster, chromosome (consisting of two sister chromatids),
what is in the cell during metaphase
chromosome, spindle fibers, centrioles. metaphase plate
what is in the cell during anaphase
centrioles, spindle fibers, sister chromasomes in chromatid form
cancer
uncontrolled cell division and growth
tumor
mass of cells that continues dividing
what makes a cell a cancer cell
contains unfixable DNA damage (mutations), doesn’t go through apoptosis instead continues dividing
cancer cells unlike normal cells can
reproduce in isolation
cancer cell functions
leech nutrients from other cells
-do not carry on bodily functions
regulators
genes that regulate proteins
telomerase
restorying telomerse, becoming immortal
metastasis
cancer cells travel to other parts of the body
what is cancer in regards to mitosis
cancer is abnormal mitosis caused by mutation
treatment to cancer
-radiation (overly mutating cancer cells so they can’t be disguised)
-chemotherapy (kill fast growing cells)
how many chromosomes are in a human body cell
46
how many chromosomes in a human sex cell
23
centromere
middle of a chromosome
counting chromosomesisreally…
counting centromeres
when do you duplicate chromosomes
interphase
from one chromatid to two chromatid’s (sister chromatids)
when do you have 46 chromosomes and 96 chromatids
after interphase, beg of prophase
mitosis resulting cells
identical
meiosis resulting cells
reduction division
gametes
reproduction cells
n
gametes
reproduction cells, haploid
n
fertilization
fusion of gametes
-creates a diploid cell
n+n=2n
zygote
body formed by fertilization
male gamete
sperm from testes
female gamete
egg from ovaries
chromosomes always pair up even if
they are visibaly different
homologous chromosomes
two chromosomes carrying same gene category from two parents
-not attached
-different than sister chromatid
where are copies on chromosomes
two centromere chromsomes (two sister chromatid’s)
where are pairs on chromosomes
/ and \
homologous pairs
diploid organisms carry two versions of each chromosome
-a duplicated chromosome, with the same genes
meiosis interphase
DNA replication occurs
-chromatin condenses into chromatid
- 46 pairs of chromosomes (96 chromatids)
tetrad
set of homologous pair
meiosis prophase 1
-nucleur envelope dissolves
-information swaps in chromosomes (creates tetrad)
-centriole moves apart, astar rays
synapsis
exchance of genetic material, from same ‘categories’
-creates variation
-genes are not lost
crossing over
-chromosomes after synapsis will have recombined information
meiosis purpose
required to produce sex cells
meiosis metaphase 1
-centrioles, spindle fibers lined up
-tetrad lined up at equator
-tetrad pairs attached to spindle fibers
meiosis anaphase 1
-spindle fibers pull apart tetrad
-segregation
-chromatids DO NOT SEPERATE, move to opposite poles
during what part of meiosis does the genetic information swap happen
meiosis prophase 1
meiosis telophase 1
-chromosomes unwind back into chromatin
-nucleur membrane starts to reappear
-cytokinesis may begin, or directly into prophase 2
*2 daughter cells that are non identical created
interkinesis
resting state between meiosis 1 and 2
-no cells duplicating
prophase 2
-chromatin recondenses into chromosomes
metaphase 2
chromosomes align at equator
anaphase 2
sister chromatids move apart to poles
telophase 2
cytokinesis happens, nuculeur membrane is reformed
-4 identical haploid daughter cells
reduction division
result of the whole process is half the orhginal chromsomes number
what stage of meiosis does crossing over happen
prophase 1
gametogenesis
generation of gametes (eg egg, sperm)
spermatogenesis
-production of male sex cells
-all sperm cells (4) receive equal amounts of cytoplasm
spermatogonium
early stage cell of sperm, prior to mitosis
autosome
every chromosome that is not a chromosome
x and y chromosome
sex chromosome
x chromosome
female
y chromosome
male
primary spermatocyte
spermatogonium growth, and maturity
secondary spermatocyte
primary spermatocyte has gone through meiosis 1
-haploid
when does spermatocyte become haploid
after meiosis 1
spermatids
undergone meiosis 2
-four unique haploids
how many spermatids are created after meiosis 2
four
maturation
spermatids are maturing/have matured into sperm cells
male spermatogenesis cycle
- spermatogonium grows
2.spermatogonium undergoes mitosis to create two diploid primary spermatocytes - undergoes meisosis 1 to turn into secondary spermatocytes
- undergoes meiosis 2 into spermatids which mature until ejaculated as sperm
spermatogenesis production site
happens in the seminiferous tubules, in testes
what does meiosis 2 produce
four unqiue haploid cells
oogenesis production site
production of ova occurs in epihelial layer of ovaries
oogenesis
production of female sex cells
-one cell recieves most cytoplasm
polar bodies
other cell that doesn’t receive cytoplasm, eventually degenerates
oogonium
starting place of oogenesis, grows until can undergo mitosis
primary oocytes
has undergone mitosis
-diploid
female cell
two x chromosomes
male cell
x and y chromosome
secondary oocyte
has undergone meiosis 1,
-created with the first polar body
(n) for both
when does meiosis 2 occur in the female cycle
if fertilization occurs
ovulated secondary oocyte (ovum)
has undergone meiosis 2
-creates 2nd polar body and ovum
1st polar body
may or may not divide a second time
-doesn’t have much of a function
another name for ovulated secondary oocyte
ovum
ovum turns into
mature egg
female sex cell cycle
1.born with primary oocytes
2. primary goes through meiosis 1, creates secondary oocyte
3. after fertilization secondary undergoes meiosis 2 and turns into a fertilized ovum
4. ovum turns into mature egg
purpose of oogenesis
-variation
-accquring haploid cell (n+n)
for the most part of multicellular life you are…
diploid
alternation of generations
referring to plant/algae
switching between asexual (mitosis) and sexual (meiosis) phases
purpose of meiosis
create haploid cells
purpose of fertilization
create diploid cells
gametes are
haploid
organisms is dominatly
diploid
gametes are formed by
meiosis
zygotes formed by
fertilization (diploid)
zygote turns into…
embyro, fetus, infant, child, adult
growth is simply…
mitosis
gomads
ovaries/testies
reductional division
meiosis going from 2n to n
fungi and algae/yeast differences
-haploid organism grows, mitosis
-gametes undergo fertilization to produce zygote (2N)
-meiosis turns back into haploid, to germinate
mitosis ends in how many pairs (d/h)
-ends intwentythreepairs
-diploid
meiosis ends in how many pairs (d/h)
-ends in 23
-haploid
chiasma
during synapsis, crossing over, intersection spot
crossing over happens during
prophase 1
recombinant chromatids
same type of information
-on different arms/areas
-still homologous
n+n=2n
fertilizaton
difference between fungi cycle and humans
humans typically stay as a diploid
-fungi stay as haploid and breifly fertilize then into meiosis right away
plants and other algae cycle
-alternate between haploid and diploid stages (equal alternation)
sporophyte-meiosis(reduction) to spores-mitosis to gametophyte-mitosis to gametes-fertilization to zygote-mitosis to sporophyte
sporophyte
diploid stage
-creates spores through meiosis
gametophyte
haploid stage
produces gametes (n) by mitosis
terms assosciated to haploid
gamete
gemetophyte
egg (ovum)
sperm
spore
terms assosciated to diploid
zygote
sporophyte
fertilized egg
nondisjunction
failure for chromosomes to seperate
why is nondisjunction more severe in meiosis
-cell is apart of zygotes of new humans, affects all their cells in that said human
(meiosis happens in gamete producing cells)
where does nondisjunction happen in meiosis (two things)
in meiosis 1 –> homologous chromosomes move to the same pole in anaphase 1
in meiosis 2 —> when chromatids fail to seperate during anaphase 2
autosomes
one of the numbered chromosomes
(not a sex chromosome)
naming of chromosome abnormalility
trisomy *number
polyploidy
having a chromosome number that is a multiple greater than two of the haploid number
benefits of polyploidy
-increases cell size
4n (tetraploid) examples
potatoes, coffee, peanuts, macintosh apples
6n (hexaploid) examples
barley, bread wheat
8n (octoploid) examples
strawberries
induced allopolyploidy
convert a sterile cross-species hybrid into a fertile allotetra-ploid
