Cell Division Flashcards
process by which cells reproduce themselves
cell division
Cell division enables multicellular organism
to grow and develop
to replace worn out and damaged tissues
Cell division enables multicellular organism
to grow and develop
to replace worn out and damaged tissues
cell division consists of two activities
karyokinesis
cytokinesis
two kinds of nuclear cell division
mitosis
meiosis
a cycle that a cell undergoes that the cell undergoes that a time it is formed until it prepares itself for cell division
cell cycle
molecules synthesized in G1
protein
RNA
3 types of RNA molecules
RRNA
TRNA
MRNA
how many hydrogen bonds between adenine and thymine
2 bonds
how many hydrogen bonds between cytosine and guanine
3 bonds
most critical stage of the cell cycle
s stage
type of cells that do not regenerate
brain cells and heart cells
arranged to be spindle fibers
microtubules
binding sites for spindle fibers
kinetochore
come from centrioles attach to kinetochore
kinetochore microtubule
grow outward but do not attach to kinetochore
nonkinetochore microtubule
radiate outward, important in the stability of the location of centrioles
aster microtubule
cells divide how many times in mitosis
once
cells divide how many times in meiosis
twice
meiosis I is also called this
reduction division
meiosis II is called this
equatorial division
homologous chromosomes (
autosomes
what pairs of chromosomes are considered as autosomes
1-22
determines the sex of the child
father
can detect a person’s genetic defect
karyotyping
also known as down syndrome
trisomy 21
spermatogenesis/oogenesis
gametogenesis
main organ of the male reproductive system
testes
immature cells (2n) in sperms
spermatogonia
spermatogonia undergo what to become a primary spermatocyte
mitosis
after undergoing mitosis has the complete set of chromosomes (spermatogenesis)
spermatocyte
spermatogonium > mitosis results in how many chromosomes
diploid (2n)
has a haploid amount of chromosomes in spermatogenesis
secondary spermatocyte
the primary spermatocyte undergoes this to become the secondary spermatocyte
meiosis I
the secondary spermatocyte undergoes this to become the early spermatid
meisosis II
number of chromosomes of a early spermatid
haploid
early spermatid undergoes this to become a late spermatid
maturation
the late spermatid undergoes maturation to become this
spermatozoa
spermatogenesis ratio
1:2:4
in the spermatogenesis ratio, the 1 in 1:2:4 is what type of sperm
1 primary spermatocyte
in the spermatogenesis ratio, the 2 in 1:2:4 is what type of sperm
2 secondary spermatocyte
in the spermatogenesis ratio, the 4 in 1:2:4 is what type of sperm
4 spermatozoa
primary reproductive organ of females
ovaries
prior to birth, the female gametes are these
oogonium (2n)
during childhood, the ovary of a female child has this
primary oocyte (2n)
each month the primary oocyte undergoes this to become a secondary oocyte
Meiosis I
this is the stage where the egg is released
secondary oocyte
contains half the number of chromosomes (n) (oogenesis)
first polar body
when the egg meets the sperm, the secondary oocyte undergoes meiosis II when this happen
fertilization
when the secondary oocyte is fertilized by a sperm this forms
ootid
ootid develops into a what after meiosis II
ovum
ratio in oogenesis
1:2:4
ratio of viability in oogenesis
1:1:1
production of sperm occurs when
every day
production of egg cells occurs when
monthyl
before birth what is the term for egg cells
oogonium
how many chromosomes in oogonium, primary oocyte, secondary oocyte, ootid, and ovum
oogonium (2n)
primary oocyte (2n)
secondary oocyte (n)
ootid (n)
ovum (n)
during childhood, the ovary is what
inactive
the secondary oocyte forms during what
puberty
how many chromosomes in spermatogonium, primary spermatocyte, secondary spermatocyte, early spermatid, late spermatid, and immature sperms
spermatogonium (2n)
primary spermatocyte (2n)
secondary spermatocyte (n)
early spermatid (n)
late spermatid (n)
immature sperms (n)
series of activities through which a cell passes from the time it is formed until it reproduces
cell cycle
last for about 90% of the cell cycle
cell division
two major activities of the cell cycle
interphase/ m phase
cell division
refers to the resting phase of cell cycle
interphase
during this stage, the replication of DNA, centrosomes and centrioles occurs and the RNA and protein needed to produce structures required for doubling all cellular components are manufactured
interphase
three distinct periods of interphase
G1
S
G2
the G in G1 stands for
growth/gap
during which cells are engaged in growth, metabolism, and the production of substances required for DNA synthesis and cell division
g1 period
highly changeable ranging from non-existent in rapidly dividing cells to days, weeks, or years
g1 period
average time period of G1
8-10 hours
cells that are intended to never divide again are permanently arrested in this stage
g1 phase
examples of cells in G1 state after about 6 months of development
nerve cells
rest in G1 phase becoming permanent cells of the central nervous system
nerve cells
is the period of interphase during which chromosomes are replicated
s period
the S in S period stands for
synthesis
what happens in S period for the DNA
double helical structure partially unwinds strands separate at points where hydrogen bonds join base pairs
what happens to the exposed base after the strands separate in s period
picks up a complementary pair
what will stop the process of exposed base finding their complementary pairs
until each of the two original DNA strands is matched and joined with a newly formed DNA strand
how long does s phase take place
6-8 hours
what happens when a cell goes through S phase
committed to enter cell division
the mitochondria divide and the cell continues to grow in preparation for cell division
g2 period
since the G-phases are stages when there are no events related to chromosomal replication, they are though of as ___
gaps or interruptions in DNA synthesis
karyokinesis
mitosis
karyokinesis is divided into what
prophase
metaphase
anaphase
telophase
finalizes cell division
cytokinesis
time required for mitosis differs with what
kind of cell
location
other factors (temperature)
how long does mitosis and cytokinesis happen
1-2 hours
somatic “body” cell division
mitosis
parent cells divide to produce what
two identical daughter cells
the process ensures that each daughter cell has the same number and kind of chromosomes as the original parent cell
mitosis
mitosis is the kind of cell division that allows what (3)
growth of multicellular organisms
asexual reproduction
wound healing
meaning of pro in prophase
before
what happens to the chromatin in prophase
condenses and shortens into chromosomes
how many identical double-stranded DNA are there in prophase
a pair
pair of double-stranded DNA molecules
chromatids
chromatids are held together by a small spherical body called
centromere
used for the proper segregation of chromosomes
centromere
protein complex that is attached to the outside of each centromere
kinetochore
what happens to the nucleoli, nuclear envelope, RNA synthesis in mitosis
nucleoli - disappears
RNA synthesis - stops
nuclear envelope - breaks down and is absorbed in the cytosol
what will the centrioles do in prophase
move at the opposite poles of the cells and start to form the mitotic spindle
three types of microtubule that form as the mitotic spindle continues to develop
nonkinetochore microtubule
kinetochore microtubule
aster microtubules
grow from centrosomes, extend inward, but do not bind to kinetochores
nonkinetochore microtubule
grow from centrosomes, extend inward, and attach to kinetochores
kinetochore microtubule
grow out of chromosomes, but radiate outward from the mitotic spindle
aster microtubules
attachment site for chromosomes and also distributes chromosomes to the opposite poles of the cell
spindle
part of prophase that the chromosomes moves toward the equator of the cell
late prophase
period when maximum condensation of chromosomes is very evident
metaphase
the centromeres of the chromatid pairs line up at the exact center of the mitotic spindle called the
metaphase plate/equatorial plane region
characterized by the splitting and separation of centromeres and the movement of two sister chromatids of each pair towards the opposite poles of the cell
anaphase
sister chromatids in anaphase are referred to as
daughter chromosomes
the movement of chromosomes is due to what in anaphase (kinetochore and nonkinetochure microtubules)
shortening of kinetochore microtubules
elongation of non kinetochore microtubules
begins as soon as chromosomal movement stops
telophase
opposite of prophase
telophase
what happens to the identical set of chromosomes at the opposite poles of the cell in telophase
it uncoils and revert to their threadlike chromatin form
what happens to kinetochore/nonkinetochore microtubules in telophase
kinetochore - disappear
nonkinetochore - elongate even more
what happens around each chromatin mass in telophase
new nuclear envelope reform around each chromatin mass
what happens to the nucleoli and mitotic spindle in telophase
new nucleoli reappear
mitotic spindle breaks up
division of parent cell’s cytoplasm and organelles
cytokinesis
occurs during the telophase stage with formation of the cleavage furrow
cytokinesis
slight indentation of the plasma membrane extending around the center of the cell
cleavage furrow
what happens when cytokinesis completes
interphase begins
result of cytokinesis
two separated daughter cells
reproductive “gamete” cell division
meiosis
how many haploid nucleis are produced in meiosis
A
four
how many chromosomes produced in mitosis
46
how many chromosomes in a daughter cell in meiosis
23
can exchange genetic material before being separated (meosis)
homologous chromosomes
is the daughter cell different from parents and each other
yes
mechanism by which gametes (sex cells) are produced, the basis of sexual reproduction
meiosis
what will happen to the number of chromosomes asexually reproducing without meiosis
would be doubled in each generation
meiosis is characterized by two successive divisions that result to the formation of haploid gametes
meiosis I and II
also called reduction division since the number of chromosomes in a cell is halved (2n -> n)
Meiosis I
preceded by interphase apparently identical to that of mitosis, DNA and organelles are duplicated and stored ATP is used
Meiosis I
stages of Meiosis I
prophase I
metaphse I
anaphase I
telophase I
substages of prophase I
leptonema/leptotene
zygonema/zygotene
pachynema/pachytene
diplonema/diplotene
diakinesis
stage of prophase I where there is an initiation of homology search
leptonema/leptotene
means “thin threads”
leptonema/leptotene
stage of prophase I where chromosomes appear like “beads-on-a-string”
leptonema/leptotene
means “yoked threads”
zygonema/zygotene
stage of prophase I where condensation continues
zygonema/zygotene
stage of prophase I where there is rough pairing
zygonema/zygotene
initial alignment of homologous chromosomes
zygonema/zygotene
stage of prophase I where bivalents form
zygonema/zygotene
what is the number of chromosomes in bivalents
n
means thick threads
pachynema/pachytene
homologous chromosomes are already distinguished under the microscope
pachynema/pachytene
stage of prophase I where there is an intimate pairing of homologous chromosomes
pachynema/pachytene
what do you call the intimate pairing of homologous chromosomes
synapsis
the four sister chromatids are evident in pachynema and form a
tetrad
suppose that 2n = 6 and n =3 , how many bivalence, tetrads in leptonema
none
suppose that 2n = 6 and n =3 , how many bivalence, tetrads in zygonema
bivalence = 3
tetrads = none
suppose that 2n = 6 and n =3 , how many bivalence, tetrads in pachynema
bivalence = none
tetrads = 3
suppose that 2n = 6 and n =3 , how many bivalence, tetrads in diplonema
bivalence = none
tetrads = 3
means “double threads”
diplonema/diplotene
stage of prophase one or more areas of the non-sister chromatids remain in contact; sites of crossing over
diplonema/diplotene
one or more areas of the non-sister chromatids remain in contact
chiasmata (sing. cihiasma)
genetic exchange between maternal and paternal chromosomes
crossing over
means “moving apart”
diakinesis
chromosome separation proceeds but as this happens, the chiasmata move towards the end of each tetrad
diakinesis
the chiasmata moving towards the end of each tetrad
terminalization
disintegration of nucleolus and nuclear membrane
diakinesis
centromeres of each tetrad attach to the mitotic spindle
diakinesis
maximum condensation of chromosomes is attained (meiosis)
metaphase I
terminal chiasmata of each tetrad are visible and appear to be the only factor holding the non-sister chromatids together
metaphase I
movement of homologous chromosomes to the metaphase plate
metaphase I
tetrads separate and dyads move toward opposite poles
anaphase I
new nuclear membrane reforms
telophase I
nucleus enter into a short interphase
telophase I
some cells proceed directly to Meiosis II, skipping this
telophase I
also called equatorial division since the haploid cells produced by meiosis I divide producing 4 haploid cells that are genetically different from each other
meiosis II
very similar to mitosis in that it results in the separation of sister chromatids
meiosis II
stages of meiosis II
prophase II
metaphase II
anaphase II
telophase II
each dyad is made up of two sister chromatids joined together by a common centromere
prophase II
alignment of centromeres at metaphase plate
metaphase II
suppose that 2n = 6 and n =3 , how many bivalence, tetrads, dyads in metaphase I
bivalence = none
tetrads = 3
dyads = none
suppose that 2n = 6 and n =3 , how many bivalence, tetrads, dyads in anaphase I
bivalence = none
tetrads = none
dyads = 6
suppose that 2n = 6 and n =3 , how many bivalence, tetrads, dyads in telophase I
bivalence = none
tetrads = none
dyads = 6 (in total), 3 (per daughter cell)
splitting of centromeres and movement of monads towards the opposite poles of the cell
anaphase II
suppose that 2n = 6 and n =3 , how many bivalence, tetrads, dyads in metaphase II
bivalence = none
tetrads = none
dyads = 6 (in total), 3 (per daughter cell)
suppose that 2n = 6 and n =3 , how many bivalence, tetrads, dyads in anaphase II
none
suppose that 2n = 6 and n =3 , how many monads in anaphase II
in total = 12
per daughter cell = 6
monads reach opposite poles
telophase II
nucleolus and nuclear membrane reform (meiosis II)
telophase II
chromosomes uncoil and become inconspicuous; cytokinesis occurs
telophase II
difference between mitosis and meiosis in the kinds of cell they divide
mitosis = somatic
meiosis - gametes
suppose that 2n = 6 and n =3 , how many monads in telophase II
total = 12
per DC = 3
difference between mitosis and meiosis in the number of divisions per cycl
mitosis = one
meiosis = two
difference between mitosis and meiosis in the number of daughter cells formed per cycle
mitosis = two
meiosis = four
difference between mitosis and meiosis in the chromosome no. of daughter cells
mitosis = diploid (2n)
meiosis = haploid (n)
difference between mitosis and meiosis in progeny/daughter cells
mitosis = genetically identical
meiosis = genetically different
difference between mitosis and meiosis in time of cycle
mitosis = throughout life
meiosis = completed after sexual maturity (humans)
difference between mitosis and meiosis in uses
mitosis = growth, repair, asexual reproduction
meiosis = sexual reproduction, generating new gene combinations
