Unit 9: Cell Cycle Flashcards
Eukaryotic chromosomes in a typical cell…
a) consist of a single circular loop of DNA
b) are visible in the cell once they condense during S phase
c) spend most of their time as tangled threads, not distinguishable by light microscopy
d) spend most of their time in pairs, joined by centromeres
e) pair up along the metaphase plate during mitosis, with connections between parental homologs
c)
When chromosomes are pulled apart at anaphase of mitosis, ____ are being separated.
a) homologous chromosomes
b) sister chromatids
c) maternally and paternally-inherited genetic material
d) identical copies of genetic material
e) b and d
e)
When viewed using light microscopy, the most obvious sign that a cell has completed mitotic prophase and transitioned into prometaphase is
a) separation of chromatids to opposite poles of the cell
b) lining up chromosomes along the equator of the cell
c) breakdown of the nuclear envelope
d) replication of DNA resulting in two sister chromatids
e) presence of synaptonemal complexes between sister chromatids
c)
Which of the following describes an event that occurs in meiosis II?
a) crossing over of non-sister chromatids
b) tetrads migrate to the metaphase plate
c) sister chromatids separate and begin moving to opposite sides of the cell
d) homologous chromosomes separate and begin moving to opposite sides of the cell
c)
Compared to somatic cell in G0, a germ cell at the completion of meiosis I has ___ amount of DNA and ___ number of chromosomes
a) half the; half the
b) the same; the same
c) the same; half the
d) double the; the same
c)
An epithelial cell lining your intestine spends most of its time in ____ of the cell cycle
a) M-phase
b) metaphase
c) interphase
d) S-phase
e) prophase
c)
G1-Cdk
a) transfers phosphate groups to target proteins
b) varies in concentration as the cell goes through the cycle
c) varies in activity as the cell goes through the cycle
d) a and b
e) a and c
e)
As a cell completes mitosis, M-Cdk (MPF) activity must decrease. How is this achieved?
a) M-Cdk is completely degraded
b) The kinase component of M-Cdk is converted to G1-Cdk, which then drives the next phase of the cycle
c) The kinase takes on a function unrelated to mitosis
d) The cyclin component is degraded
e) the kinase is degraded; concentration of the cyclin remains constant, but without the cyclin-dependent kinase, active M-Cdk is not formed
d)
A cell that is terminally differentiated
a) will never divide again
b) is capable of carrying out a specific function within the organism
c) can no longer function, and will soon die
d) a and b
e) a and c
d)
Cdk inhibitors
a) remove phosphates from Cdks, thereby inactivating them
b) can bind to G1 / S-Cdk and prevent progression into S Phase
c) promote unregulated cellular proliferation
d) can prevent division in cells with damaged DNA
e) both b and d
e)
Many tumour suppressor genes code for proteins that
a) lead to the halting of the cell cycle if DNA damage is detected
b) block the effects of mitogens
c) drive the transcription of Cdk inhibitors
d) are activated once cells become cancerous
e) a and c
e)
A cell that express a proto-oncogene will
a) probably become cancerous
b) become terminally differentiated
c) undergo uncontrolled cell division
d) undergo normal cell division in response to appropriate signals
e) a and c
d)
In response to DNA damage that is not able to repair, a human cell should
a) release cytochrome c from the mitochondria and activate caspases
b) shift the balance of Bcl-2 regulatory proteins to pro-apoptotic members
c) undergo apoptosis
d) a and c
e) a, b and c
e)
Rb is an example of
a) oncogene
b) proto-oncogene
c) mitogen
d) tumor supressor
d)
Inheriting a non-functional copy of a tumour suppressor gene (e.g. p53) from one of your parents would
a) cause non-disjunction
b) predispose you to cancer if your other copy of p53 becomes mutated
c) promote mitosis in your terminally differentiated cells
d) prevent mitosis in all your cells
e) cause uncontrolled cell division in cells lining your intestine
b)
The main purpose of the spindle checkpoint is to prevent
a) cancer
b) mutations
c) non-disjunction
d) terminal differentiation
e) DNA replication
c) non-disjunction = failure of homologous chromosomes to separate during cell division
During which phases of the cell cycle do chromosomes exist in doubled state?
a) late M and G1
b) G1 and S
c) G2 and part of M
d) all of interphase
e) G0 and G1
c)
Levels of Cdk activity change during the cell cycle, in part, because
a) levels of their cyclin regulatory components change during the cycle
b) Cdk degradation precedes entry into the next phase of the cell cycle
c) the Cdks phosphorylate each other
d) the Cdks activate their cyclin regulatory components
e) they are phosphorylated by their cyclin regulatory components
a)
A cell that passes the Restriction point (G1/S) will likely
a) undergo apoptosis
b) undergo chromosome duplication
c) continue to divide only if it is a cancer cell
d) move into the G0 phase
e) experience a drop in MPF concentrations
b)
Pause or halting the cell cycle at G1/S checkpoint
a) indicates that the cell is probably cancerous
b) would happen as a result of errors during DNA replication
c) would involve the degradation of p53
d) could involve the inhibition of G1/S - Cdk and S-Cdk complexes by p21
d)
Which of the following statements about apoptosis is/are TRUE
a) virtually all animal cells contain procaspases, which can be activated to trigger a cell suicide program
b) cells that constitutively express Bcl-2 will be more prone to undergo apoptosis
c) Bax and Bak inhibit apoptosis by binding to procaspases
d) a and c
e) a, b and c
a)
DNA is composed of four nucleosides; adenosine, cytidine, thymidine, and guanosine. If radioactive thymidine were introduced into the growth medium of the cells, it would be incorporated into the DNA molecule
a) as the cell passes the G1 restriction point
b) when centromeres so the two chromosomes can be seperated
c) at any point in the cell cycle
d) during the G1 phase when the cell does most of its growth
e) during S phase
e)
What is the major difference between meiosis II and mitosis?
a) Meiosis II results in separation of homologues, while mitosis separates sister chromatids
b) crossing over takes place in meiosis II but not in mitosis
c) homologues on the metaphase plate are paired up in meiosis II but independently arranged in mitosis
d) meiosis II takes place in a cell with ‘n’ chromosomes, while mitosis takes place in cells with 2n chromosomes
d)
Gene ‘X’ codes for a protein that, when activated by phosphorylation, binds to and inhibits G1/S-Cdk. Gene X would be described as
a) proto-oncogene
b) second messenger
c) oncogene
d) tumor suppressor
e) mitogen
d)
Function of G1-Cdk
help with passage through restriction point
Function of G1/S-Cdk
Commit cell to DNA replication
Function of S-Cdk
Carry out DNA replication
Function of M-Cdk
Promote events of mitosis
What occurs during G1 phase?
Regular cell activity and increasing cell size
What occurs during S Phase
DNA Replication
What occurs during G2 phase?
Completion of mitosis prep, condensing of chromosomes start
What occurs during M Phase?
Mitosis - chromosomes finally condense enough to be visible
Cytokinesis
G1/S Checkpoint?
Environment favourable? Damaged DNA?
G2/M Checkpoint?
All damaged DNA repaired? All DNA replicated?
Spindle Checkpoint?
Chromosomes attached to mitotic spindle?
p53
Tumour suppressor
detects DNA damage at G1/S checkpoint
Causes synthesis of G1/S-Cdk & S-Cdk inhibitors
p21
Cdk Inhibitor
Suppresses G1/S-Cdk and S-Cdk following DNA damage
