Start Meiosis -- Lecture 8 Flashcards
cytokinesis (what is it)
process of dividing 1 cell into 2
cytokinesis in animal cells:
animal cells use a ___
contractile ring
cytokinesis in animal cells:
___ use a contractile ring
animal cells
cytokinesis in animal cells:
contractile ring is composed of
actin microfilaments
myosin motor proteins
cytokinesis in animal cells:
in the contractile ring, ___ and ___ contract rapidly to pinch cell in 2, forming a cleavage furrow
actin microfilaments
myosin motor proteins
cytokinesis in animal cells:
in the ___, actin microfilaments and myosin motor proteins contract rapidly to pinch cell in 2, forming a cleavage furrow
contractile ring
cytokinesis in animal cells:
in the contractile ring, actin microfilaments and myosin motor proteins contract rapidly to pinch cell in 2, forming a ___
cleavage furrow
cytokinesis in plants:
vesicles (definition)
membrane-bound delivery vehicles
cytokinesis in plants (steps)
1) vesicles accumulate in middle of cell
2) vesicles bring the necessary material to form a temporary structure called a cell plate
3) cell plate goes thru a series of biochemical changes and becomes the cell wall
vesicles in middle –> cell plate –> cell wall
chromosome terminology:
In human cells: in G1: there are 46 one-chromatid ___
chromosomes
chromosome terminology:
In human cells: in G1: there are ___ one-chromatid chromosomes
46
chromosome terminology:
In human cells: in G1: there are 46 ___-chromatid chromosomes
one
chromosome terminology:
In ___ cells: in G1: there are 46 one-chromatid chromosomes
human
chromosome terminology:
the chromosomes are in ___: 1 from Mom, 1 from Dad
pairs
chromosome terminology:
each pair chromosomes are referred to as ___ or ___
homologs
homologous chromosomes
chromosome terminology:
homologous chromosomes are very similar but ___
slightly different
chromosomes revisited:
homologous chromosomes contain same ___ but have slightly different ___
genes
DNA sequences
chromosomes revisited:
before DNA replication, each homolog has ___ chromatid
1 chromatid
chromosomes revisited:
after DNA replication, each homolog has ___
2 chromatids
ploidy (definition)
of homologs of each chromosome in a cell
diploid (definition)
has 2 homologs of each chromosome – 1 from each parent
2n
haploid (definition)
have 1 homolog of each chromosome
n or 1n
polyploid (definition)
have 3 or more homologs of each chromosome
diploid cells (2n):
46 one-chromatid chromosomes
how many homologous pairs?
23
haploid cells (n):
23 one-chromatid chromosomes
how many homologous pairs?
none
mitosis vs. meiosis:
mitosis (definition)
a eukaryotic cell divides and makes a clone of itself
each new cell has the same # of chromosomes as the original cell
mitosis vs. meiosis:
meiosis (definition)
a eukaryotic cell divides
each new cell has 1/2 the # of chromosomes as the original cell
mitosis vs. meiosis:
why would a eukaryote go thru meiosis?
reproduction
meiosis enables reproduction
each parent is diploid (46 one-chromatid chromosome)
thru meiosis, their gametes are haploid (23 one-chromatid chromosomes)
gametes fuze into zygote, a 1-celled embryo, which is diploid (46 one-chromatid chromosomes)
gametogenesis (definition)
making sperm and egg cells
spermatogenesis results in…
results in 4 viable haploid sperm cells
spermatogenesis (process)
1, primary spermatocyte (diploid)
thru meiosis becomes…
4, mature sperm cells (haploid)
oogenesis results in…
results in 1 viable egg cell and 3 nonviable egg cells called polar bodies (all haploid)
polar bodies
3 of the 4 egg cells produced in oogenesis which are nonviable
oogenesis (process)
1, primary oocyte (diploid)
thru meiosis becomes…
4 egg cells (haploid)
1 viable egg cell and 3 polar bodies (nonviable egg cells)
meiosis overview (meiosis I):
beginning of the process
cell in G1:
- 4 one-chromatid chromosomes –> 1 diploid cell
S-phase:
- 4 two-chromatid chromosomes –> 1 diploid cell
Meiosis I (first of 2 cell divisions): - homologous pairs segregate into different cells --> 2 haploid cells
meiosis overview (meiosis I):
after meiosis I
there are 2 haploid cells, each w/ 2 two-chromatid chromosomes
meiosis overview (meiosis I):
which meiosis is called reduction division?
meiosis I
meiosis overview (meiosis I):
why is meiosis I called reduction division?
because the chromosome # is less
meiosis overview (meiosis II):
meiosis II (the 2nd of 2 cell divisions) – what happens?
chromatids separate and segregate into different cells
meiosis overview (meiosis II):
after meiosis II
4 cells each w/ 2 one-chromatid chromosomes –> haploid
