Bio 200 Exam 3 with 100% Correct
Answers
Chromosomes - ANSWER-Highly condensed DNA. Each daughter cell needs to get
one copy of every chromosome (22 pairs plus 1 pair of sex chromosomes)
Mitosis Stages - ANSWER-Interphase--> Metaphase--> Prophase--> Anaphase--
>Telophase
G2 Checkpoint - ANSWER-Pass this checkpoint if:
chromosomes have replicated successfully
DNA is undamaged
activated MPF is present
Metaphase Checkpoint - ANSWER-Pass this checkpoint if:
all chromosomes are attached to spindle apparatus
G1 Checkpoint - ANSWER-Pass this checkpoint if:
cell size is adequate
nutrients are sufficient
social signals are present
DNA is undamaged
Totipotent - ANSWER-all fates possible (gametes)
Pluripotent - ANSWER-multiple fates are possible (stem cells)
Unipotent - ANSWER-one fate possible, not yet structured
Differentiated - ANSWER-recognizable structured for a single cell fate
Estradiol - ANSWER-stimulates development of the female reproductive tract, growth of
ovarian follicles and growth of breast tissue
Progesterone - ANSWER-Secreted by the corpus luteum AFTER ovulation, causes
uterine lining to thicken
Lutenizing Hormone - ANSWER-stimulates estrogen production, ovulation and
formation of corpus luteum
, Follicle-Stimulating Hormone - ANSWER-stimulates growth of eggs and follicles in
ovaries (or sperm production in testes)
Social Control - ANSWER-• In multicellular organisms, cells divide in response to
signals from other cells
Rb, E2F and S phase - ANSWER-• In G0 cells, arrival of growth factors (polypeptides or
small proteins that stimulate cell division) stimulates production of E2F, a key regulatory
protein
• When E2F is activated it triggers expression of genes required for S phase
• Rb protein: A tumor suppressor protein that helps regulate progression of a cell from
the G1 phase to the S phase of the cell cycle. Defects in Rb protein are found in many
types of cancer.
• When E2F is first produced, it binds to Rb. When bound to Rb E2F cannot activate the
genes required for S phase. As long as Rb stays bound to E2F, the remains in G0.
How growth factors move cells through the G1 checkpoint - ANSWER-o 1) Enough
growth factors arrive to override the inhibitory effects of Rb
o 2) Growth factors stimulate production of E2F and cyclins that are specific to the G1
checkpoint
o 3) E2F continues to bind to Rb and remain inactive. Cyclin binds to Cdk; Cdk is
phosphorylated and inactive
o 4) Cdk is activated by dephosphorylation. It catalyzes phosphorylation of Rb.
o 5) The phosphorylated Rb changes shape and no longer binds to E2F. Rb releases
E2F.
o 6) E2F enters nucleus and triggers production of S-phase proteins.
• High concentrations of growth factors function as a social signal: signal to override Rb
and pass the G1 check point and divide
Cells become cancerous when social controls fails - ANSWER-divide in absence of the
go-ahead signal from growth factors
• Two things can go wrong:
o 1 ) excessive amounts of growth factors
o 2) cyclin production in the absence of growth signals
Cases of uncontrolled cell division - ANSWER-o 1) genes that stop or slow the cell cycle
(tumor repressor genes)
When Rb is missing or does not bind normally to E2F, any E2F that is present pushes
the cell through the G1 checkpoint and into S phase
o 2) genes that trigger cell growth and division by initiating specific phases in cell cycle
Proto-oncogenes converted to oncogene
Answers
Chromosomes - ANSWER-Highly condensed DNA. Each daughter cell needs to get
one copy of every chromosome (22 pairs plus 1 pair of sex chromosomes)
Mitosis Stages - ANSWER-Interphase--> Metaphase--> Prophase--> Anaphase--
>Telophase
G2 Checkpoint - ANSWER-Pass this checkpoint if:
chromosomes have replicated successfully
DNA is undamaged
activated MPF is present
Metaphase Checkpoint - ANSWER-Pass this checkpoint if:
all chromosomes are attached to spindle apparatus
G1 Checkpoint - ANSWER-Pass this checkpoint if:
cell size is adequate
nutrients are sufficient
social signals are present
DNA is undamaged
Totipotent - ANSWER-all fates possible (gametes)
Pluripotent - ANSWER-multiple fates are possible (stem cells)
Unipotent - ANSWER-one fate possible, not yet structured
Differentiated - ANSWER-recognizable structured for a single cell fate
Estradiol - ANSWER-stimulates development of the female reproductive tract, growth of
ovarian follicles and growth of breast tissue
Progesterone - ANSWER-Secreted by the corpus luteum AFTER ovulation, causes
uterine lining to thicken
Lutenizing Hormone - ANSWER-stimulates estrogen production, ovulation and
formation of corpus luteum
, Follicle-Stimulating Hormone - ANSWER-stimulates growth of eggs and follicles in
ovaries (or sperm production in testes)
Social Control - ANSWER-• In multicellular organisms, cells divide in response to
signals from other cells
Rb, E2F and S phase - ANSWER-• In G0 cells, arrival of growth factors (polypeptides or
small proteins that stimulate cell division) stimulates production of E2F, a key regulatory
protein
• When E2F is activated it triggers expression of genes required for S phase
• Rb protein: A tumor suppressor protein that helps regulate progression of a cell from
the G1 phase to the S phase of the cell cycle. Defects in Rb protein are found in many
types of cancer.
• When E2F is first produced, it binds to Rb. When bound to Rb E2F cannot activate the
genes required for S phase. As long as Rb stays bound to E2F, the remains in G0.
How growth factors move cells through the G1 checkpoint - ANSWER-o 1) Enough
growth factors arrive to override the inhibitory effects of Rb
o 2) Growth factors stimulate production of E2F and cyclins that are specific to the G1
checkpoint
o 3) E2F continues to bind to Rb and remain inactive. Cyclin binds to Cdk; Cdk is
phosphorylated and inactive
o 4) Cdk is activated by dephosphorylation. It catalyzes phosphorylation of Rb.
o 5) The phosphorylated Rb changes shape and no longer binds to E2F. Rb releases
E2F.
o 6) E2F enters nucleus and triggers production of S-phase proteins.
• High concentrations of growth factors function as a social signal: signal to override Rb
and pass the G1 check point and divide
Cells become cancerous when social controls fails - ANSWER-divide in absence of the
go-ahead signal from growth factors
• Two things can go wrong:
o 1 ) excessive amounts of growth factors
o 2) cyclin production in the absence of growth signals
Cases of uncontrolled cell division - ANSWER-o 1) genes that stop or slow the cell cycle
(tumor repressor genes)
When Rb is missing or does not bind normally to E2F, any E2F that is present pushes
the cell through the G1 checkpoint and into S phase
o 2) genes that trigger cell growth and division by initiating specific phases in cell cycle
Proto-oncogenes converted to oncogene
