Download Biol 211 (2) Chapter 12 KEY

Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
Biology 211 (2) Week 9!
!
Chapter 12!
VOCABULARY: !
Anaphase: A stage in mitosis Cell division: Creation of
new cells by division of
or meiosis during which
chromosomes are moved to preexisting cells
opposite poles of the
spindle apparatus
Centromere: joint point
where the two sister
chromatids meet
Chromatid: One of the two
identical double-stranded
DNAs composing a
replicated chromosome that
is connected at the
centromere to the other
strand.
Chromosomes: Genecarrying structure consisting
of a single long molecule of
double-stranded DNA and
associated proteins.
Cyclin: One of several
regulatory proteins whose
concentration fluctuate
cyclically throughout the
cell cycle. Involved in the
control of the cell cycle via
cyclin-dependent kinases
Cyclin-dependent kinase
(Cdk): Any of several related
protein kinases that are
functional only when bound
to a cyclin and are activated
by other modifications.
Involved in the control of
the cell cycle
Cytokinesis: Division of the
cytoplasm to form two
daughter cells. Typically
occurs immediately after
division of the nucleus by
mitosis or meiosis
G1 phase: The phase of the
cell cycle that constitutes
the first part of interphase
before DNA synthesis
G2 phase: The phase of the
cell cycle between synthesis
of DNA (S phase) and mitosis
(M phase); the last part of
interphase
Gametes: A haploid
reproductive cell that can
fuse with another haploid
cell to form a zygote. (EX:
sperm and egg)
Kinetochores: A protein
complex at the centromere
where microtubules attach
to the chromosome.
Meiosis: In sexually
reproducing organisms, a
special two-stage type of
cell division in which one
diploid parent cell produces
haploid gametes, results in
having of the chromosome
number
Metaphase: A stage in
mitosis or meiosis during
which chromosomes line up
in the middle of the cell
Mitosis: The process of
nuclear division that results
in two daughter nuclei
genetically identical with
the parent nucleus
MPF: (M-phase-promoting
factor) A complex of a cyclin
and cyclin-dependent kinase
that, when activated,
phosphorylates a number of
specific proteins needed to
initiate mitosis
p53: A tumor-suppressor
protein that responds to
DNA damage by stopping the
cell cycle, turing on DNA
repair machinery, and may
trigger apoptosis
Prometaphase: A stage in
mitosis or meiosis during
which the nuclear envelope
breaks down and
microtubules attach to
kinetochores
Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
Prophase: The first stage in
mitosis or meiosis during
which chromosomes become
visible and the spindle
apparatus forms
S phase: They phase of the
cell cycle during which DNA
is synthesized and
chromosomes are replicated
Sister chromatids: The
paired strands of a recently
replicated chromosome,
which are connected at the
centromere and eventually
separate during anaphase of
mitosis and meiosis II.
Interphase: non-dividing
phase
Spindle apparatus: The
array of microtubules
responsible for moving
chromosomes during mitosis
and meiosis; includes
kinetochore microtubules,
polar microtubules and
astral microtubules
Telophase: The final stage in
mitosis or meiosis during
which daughter
chromosomes have
separated and new nuclear
envelopes begin to form
around each set of
chromosomes
Tumor suppressors: A
protein (e.g. p53 or Rb) that
prevents cell division, such
as when the cell has DNA
damage. Mutant genes that
code for tumor suppressors
are associated with cancer.
KEY CONCEPTS:!
1. Why does replication occurs in an uncondensed state?!
1. It is easier for the polymerase to copy the DNA when it is unraveled rather than
raveled. !
2. Diagram the cell cycle, labeling the G1, G2, S and M phases. Draw the chromosomes
present at each stage. How much DNA is in the cell at G2 compared to G1? How much
DNA is in each daughter cell compared to the parent cell? !
Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
3. Chromosome replication occurs only during _______.!
1. S Phase in the Interphase, there is no chromosome replication occurring during M
Phase!
4. Diagram the sub-phases of mitosis. Label and describe each phase.!
5. What three structures make up the the mitotic spindle? Define each.!
1. Spindle fibers: what the microtubules are made of!
2. Polar microtubules: push the poles of the cell away from each other during mitosis!
3. Kinetochore microtubules: pull chromosomes to the poles of the cell during mitosis!
6. Diagram the concentrations of cyclin and MPF-Cdk during the cell cycle. How does
MPF trigger the start of mitosis?!
1. One phosphorylation on Cdk =active <— triggers the start of mitosis!
!
2. Two phosphorylation on Cdk=inactive <—have two until M Phase begins!
Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
7. Compare and contrast G1, G2 and M checkpoints. Why is it important for the cell cycle
to have checkpoints? What would happen to a cell that has a damaged p53 gene so that
it cannot make functional p53 protein?!
1. It is important because cells that fail a checkpoint are marked with a p53 gene and
labeled for cell death. If a cell has a damaged p53 gene, the cell may pass a
checkpoint, even if they have failed it. This will lead to uncontrolled growth (i.e.
cancer).