Lecture 16 Flashcards
____ phase is essentially eliminated in rapidly dividing cells
G1 Phase
Non dividing cells get permanently stuck in G1 phase going, then go into the ____ phase
G0
The _____ of cell division can also respond to changes in environmental conditions
Rate
______________ _________ (MPF) is present in the cytoplasm of M-phase cells and induces mitosis in all eukaryotes
Mitosis - promoting factor
MPF is composed of ___ distinct subunits: a protein kinase and a cyclin
Two
The protein _____ is an enzyme that catalyzes the transfer of a phosphate group from ATP to target protein (phosphorylation)
Kinase
The _____ subunit functions a a regulatory protein
Cyclin
The concentration of MPF cyclin ________ during interphase, then peaks in M phase before decreasing again
Increases
The MPF protein kinase is a cyclin-__________ kinase (Cdk) that is active only when bound to the cyclin subunit.
Dependent
When cyclin proteins are high, more MPF is active and the target proteins are __________, initiating mitosis
Phosphorylated
A ________ is an enzyme that can phosphorylation a protein (add a phosphate group)
Kinase
The MPF activity peaks at the ____ Phase
M
After the MPF binds to cyclin,MPF’s Cdk subunit becomes phosphorylated at two sites, rendering it _______
Inactive
Late in G2 phase enzymes cause one of the phosphate groups on the Cdk subunit to drop off.
This dephosphorylation reaction changes MPF’s _______, activating it.
Shape
Once MPF is activated, it triggers a chain of events, culminating in the condensation of chromosomes and formation of the mitotic _________ apparatus
Spindle
During anaphase, an enzyme complex begins ______ MPF’s cyclin subunit, then MPF triggers a chain of events that leads to its own destruction.
Degrading
When more and more ______ binds to MPF, leads to phosphorylation but is still inactive
Cyclin
Late G2 enzyme, dephosphorylates, MPF is ________.
Active
Anaphase - and enzyme _____ cyclin and renders, MPF deactivated
Degrades
Cell Cycle check points :
1.) G1 checkpoint
- the cell “decides” to divide
2.) G2 checkpoint (has everything in needs to replicate)
- the cell make a commitment to mitosis
3.) ___-Phase checkpoint
-the cell ensures tat all chromosomes are attached to the spindle
M Phase
G1 Checkpoint:
- Cell size is adequate
-nutrients are sufficient
- social signals are present
- ___ is undamaged
DNA
Mature cells do not pass the __ Phase, they go into the G0 Phase
G1
G2 checkpoint:
- chromosomes have ________ successfully
-DNA is undamaged
-activated MPF is present
Replicated
M-Phase checkpoint:
- chromosomes have attached to spindle apparatus
- chromosomes have properly segregated and ___ is absent
MPF
G1 checkpoint determines whether the cell will continue through the cycle and divide, or ____ the cycle to enter the G0 phase
Exit
The _____ protein either pauses the cell cycle or initiates apoptosis (causes the cell to die) if the DNA is physically damaged.
P53
Tumor suppressor: damage to the ___ gene can lead to uncontrolled cell division
p53
G2 checkpoint is controlled by ___
MPF
The M-Phase checkpoint prevents _________ chromosome separation that could give daughter cells the wrong number of chromosomes
Incorrect
The three ____________ checkpoints prevent the division of cells that are damaged of that have other problems, and they prevent the growth of mature cells that should stay in the G0 state
Cell-cycle
_______ is a common, sometimes lethal disease that effects many humans
Caused by:
- uncontrolled cell growth, that invade nearby tissues, and spread to other sites in the body (metastasize)
Cancer
_____ cancers arise from cells in which cell-cycle checkpoints have failed
(Also related to when p53 fails)
ALL
_______ - oncogenes:
- Tell cells to go (act as gas)
-Defects make proteins required for cell growth active when they should not be
Proto
________-suppressor genes:
-Tell cells to stop (act as break)
- Defects that prevent tumor suppressor genes from shutting down the cell cycle (break failure)
tumor
_______ __________ - are often proteins that can bind to cell surface receptors and allow the cell to undergo cell division
Growth Factors
___________ - can cause cancer when introduced into a cell
Oncogenes
________ inhibition is one such signal. As cells grow and touch one another, they send signals to stop growing
Contact
Cancer cells ignore these signals through mutations in proteins that prevent the cell cycle from progressing. These regulatory proteins are called _________ suppressors
Tumor
When tumor suppressors are mutated, the cell cycle will _______ when it should not
Progress
Cancer cells that metastasize have lost cell _________.
adhesion
When a checkpoint is activated due to DNA damage, the cell tried to repair the damage through DNA _______ mechanisms. If the damage is too far gone and unrepairable the cell with undergo Apoptosis (program cell death)
Repair
Cancer cells ignore these signals through mutations in proteins that prevent the cell cycle from progressing. These regulatory proteins are called _______ suppressors.
Tumor
When tumor suppressors are mutated, the cel cycle will ______ when it should not.
Progress
Due to programmed cell death (p53) the cell will ___ if it can not be fixed
Die
When a checkpoint is activated due to DNA damage, the cell tried to repair the damage through DNA ______ mechanisms.
Repair
If a cell is damaged to much, the cell activates the Program Cell Death or ________ “POP the cell”
Apoptosis
If an apoptotic signal is _________, the cell will not die and it will continue through the cell cycle.
Mutated
ASE = _________
Enzyme
Most cancers result from _______ defects in cell-cycle regulation.
Multiple
Adding a phosphate group .
Phosphorylation
Removing a phosphate group
Dephosphorylation
A family of enzymes that regulate cell division.
Cyclin-dependent Kinase (Cdk)
The MPF cyclin is specific to the _____
MPF
A proto-oncogenes is a normal gene that helps a cell, and an oncogene is a _________ proto-oncogene that can cause cancer
Mutated
Which phase of the cell cycle would most adult quiescent cells be in ?
A.) G1
B.) G2
C.) M
D.) G0
D.) G0
What is the relationship between cyclin and the MPF?
A.) Substrate to the enzyme
B.) Allosteric regulatory molecule
C.) Active site antagonist
D.) Competitive inhibitory molecule
B.) Allosteric regulatory molecule
Which of the following is not a true statement?
A.) The rate of cell division in the human body is approximately equal to the rate at which cells become damaged or die.
B.) Normal cells have mechanisms that regulate cell division.
C.) The inability to control cell division may result in cancer.
D.) All cells undergo repeated cell division throughout their lifetime.
E.) With the exception of blood cells, human cells remain in one location throughout their lifetime.
D.) All cells undergo repeated cell division throughout their lifetime.
(Mature cells often go into G0, instead of continuing through the cycle)
(Some cells, but not all, nerves are usually in G0 Phase)
