DAT bio chapter 5 Cell Division Flashcards
Genome
- all the DNA in a cell.
Chromosome
composed of a single DNA molecule. Multiple chromosomes up the entire genome.
Homologous chromosome pairs
Two different copies of the same chromosome. one copy is give by the mother and the other copy given by the father
Sister chromatids
identical copies of a replicated chromosome. joined together at the centromere to form a dyad
Dyads -
replicated chromosomes containing
two sister chromatids that look like an “X”.
Centromeres -
- regions of DNA that connect
sister chromatids in a dyad.
Kinetochores -
proteins on the sides of
centromeres that help microtubules pull sister
chromatids apart during cell division.
Karyokinesis
division of the nucleus.
Cytokinesis
physical division of the
cytoplasm and cell membrane.
Parent cell
one parent cell produces two
daughter cells after division.
Ploidy
describes the number of chromosome
sets found in the body. Humans are diploid
because they contain two sets of
chromosomes (46 chromosomes, 23 pairs),
one from each parent. However, they also
have haploid cells (gametes) that only contain
one chromosome set (23 chromosomes).
Sex chromosomes
- one pair in the human
body; they determine sex.
Autosomes -
- 22 pairs in the human body; they
are nonsex chromosomes.
Gametes -
haploid cells (sperm and eggs).
Germ cells
diploid cells that divide by meiosis
to produce gametes.
Gametocyte
- eukaryotic germ cells that can
either divide to form more gametocytes or
produce gametes.
Somatic cells
- all body cells excluding the
gametes. Diploid in humans.
Cell cycle is divided into what two phases?
interphase (G1 , G0 , S,
and G2 ) and the M phase.
what percent of the cell cycle happens in during interphase?
90%
Where does karyokinesis and cytokinesis occur.
M phase
DAT Mnemonic for the cell cycle:
Go = Gap Phase 1 (G1 ) of interphase Sam = Synthesis Phase (S) of interphase Go = Gap Phase 2 (G2 ) of interphase Make = Mitosis of the M phase Cake = Cytokinesis of the M phase
Steps for interphase (Gap phase 1 (G1 )
cell grows in preparation
for cell division. Also checks for favorable
conditions. If favorable, cell will enter S phase.
If unfavorable, cell will enter G0 phase.
What is G0 phase
- cells still carry out their
functions but halt in the cell cycle. Cells
that do not divide are stuck here.
Steps for interphase (Synthesis phase (S))
Centrosome is duplicated
DNA is replicated. Each chromosome replicates to form two sister chromatids held at a centromere
Steps for interphase (Gap phase 2 (G2)
cell continues to grow and
prepare for cell division by checking DNA for
any errors after replication. Also checks for
mitosis promoting factor (MPF), which needs
to be present in adequate amounts for cell
cycle continuation. Organelles are replicated
here.
What is microtubule organizing centers? where are they present?
Present in eukaryotic cells. they organize extension
of microtubules, which are made of the protein
tubulin. MTOCs are responsible for forming the
spindle apparatus, which guides chromosomes
during karyokinesis.
Centrosomes
organelles found in animal cells
that contain a pair of centrioles. They act as
microtubule organizing centers (MTOCs).
3 microtubules in the spindle apparatus
Kinetochore microtubules
Astral microtubules
Polar microtubules
Kinetochore microtubules
extend from
centrosomes and attach to kinetochores on
chromosomes.
Astral microtubules
extend from
centrosomes to the cell membrane to orient
the spindle apparatus.
Polar microtubules
extend from the two
centrosomes and connect with each other.
They push centrosomes to opposite ends of
the cell.
Centrioles
hollow cylinders made of nine
triplets of microtubules (9x3 array).
Centrosomes location
located near the nucleus and contain a pair of
centrioles oriented at 90 degree angles to one
another (attached to each other by
interconnecting fibers). They replicate during the
S phase of the cell cycle so that each daughter cell
after cell division has one centrosome.
what material surrounds the
centrioles and is responsible for microtubule
nucleation (anchoring tubulin to start microtubule
extension).
pericentriolar material
What is microtubule nucleation>
(anchoring tubulin to start microtubule
extension).
Cilia and flagella
nine doublets of
microtubules with two singles in the center (9+2
array).