Cell cycle Flashcards
1
Q
interphase
A
- cell undergoes normal growth and metabolism
- prepares for cell division
- Gap 1
- Synthesis of DNA
- Gap 2
2
Q
Gap 1
A
- G1
- active metabolism
- accumulation of building blocks and energy
3
Q
Synthesis of DNA
A
- S
- DNA replication occurs
- each DNA molecule produces identical copy
- cetrosome is duplicated
4
Q
Gap 2
A
- G2
- active metabolism
- protein synthesis
- duplication of organelles
- once in this phase, everything is sped up
5
Q
G0
A
- resting
- a period in the cell cycle in which the cell is not dividing of preparing to divide
6
Q
Quiescent state
A
- G0 resting state
- cell is not dividing or preparing to divide
7
Q
terminally differentiated state
A
- cells that leave the cell cycle and do not re-enter the cell cycle
- cells just die and get replaced
- skin cells
8
Q
reversible quiescent G0 phase
A
- capable to return to the cell cycle
- stem cells
- hepatocytes
9
Q
Mitotic phases
A
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
10
Q
prophsae
A
- chromosomes condense and become visible
- spindle fibers emerge from centrosomes
- break down nuclear envelope
- nucleolus disappears
11
Q
prometaphase
A
- chromosomes condense more
- kinetochores appear at centromeres
- miotic spindle microtubules attach to kinetochores
- centrosomes move toward opposite poles
12
Q
metaphase
A
- miotic spindle is fully developed
- centrosomes are at opposite poles
- chromosomes lined up in the middle
- each sister chromatid is attached to a spindle fiber
13
Q
anaphase
A
- cohesion proteins that bind sister chromatids break down
- sister chromatids change names and are pulled toward poles
- non-kinetochore spindle fibers lengthen to elongate cell
14
Q
when do sister chromatids change names and what is their new name
A
- anaphase
- chromosomes
15
Q
telophase
A
- chromosomes make it to opposite poles and decondense
- nuclear envelope surrounds each set of chromosomes
- mitotic spindles break down
16
Q
Cytokinesis animal cells
A
-cleavage furrow separates the daughter cells
17
Q
cytokinesis plant cells
A
-cells plate separates daughter cells
18
Q
How many internal checkpoints are there?
A
3
19
Q
G1 checkpoint
A
-restriction check for.. -cell size -nutrients -growth factors -DNA damage
20
Q
G2 checkpoint
A
check for…
- cell size
- accurate DNA replication
- if mistakes, the cell cycle will stop
- avoid producing mutated cell
21
Q
M checkpoint
A
check for…
- chromosome attachment to the spindle
- make sure they separate into each daughter cell
22
Q
positive regulation molecules
A
- cyclins
- Cdk
23
Q
positive regulation
A
-allow cell to move to the next phase
24
Q
cyclins
A
- changes of different cyclins throughout the cell cycle
- direct correlation between cyclin accumulation and the 3 checkpoints
- sharp decline in cyclin levels following each checkpoint
25
what degrades cyclins?
-cytoplasmic enzymes
26
when are cyclins active?
-when bond to respective Cyclin-dependent kinase
27
Cdk
- cyclin binds to Cdk
- complex is phosphorylated
- activated complex phosphorylates target protein
- active target protein advances through the cell cycle
28
What cyclin is continuously on throughtout the cell cycle>
-Cyclin D
29
Negative regulation molecules
- Rb
- p53
- p21
30
Rb regulation of the cell
- negative regulation
- controls transcription of genes necessary for transition into S phase
- UNphosphorylated Rb binds to transcription factor E2F so it cannot bind to DNA and transcription is blocked
31
phosphorylated Rb
- triggered by cell growth
- releases E2F
- allows advancing in the cell cycle
32
Rb
- retinoblastoma protein
| - prevents initiation of the cell cycle in G1 phase
33
p53 regulation of the cell
- transcriptional repressor
- can repress transcription and promote apoptosis through interaction of apoptotic regulators in cytosol
- detects cell damage
34
what can p53 do to the cell cycle?
1. program for apoptosis
OR
2. recruit proteins to help the damage then restart the cell cycle
35
p21 regulation of the cell
- inhibiting the activity of cyclin E-associated CDK2
- prevents E2F-mediated gene transcription and cell cycle progression
- induced in response to p53
36
Mitogens
- EXTERNAL stimuli that cause the cells to proliferate
- make cell return to G1 if in G0
- starts cell division
37
intergins
-mitogens provided by extracellular matrix
38
mitogenic
-cell-to matrix contact
39
antimitogenic
- cell-to-cell contact
- contact inhibition
- there are too many cells! stop dividing!
40
distant sources that supply extracellular signals
- growth factors
| - cytokines
41
platelet derived growth factor
- PDGF
| - participates in wound healing
42
epidermal growth factor
- produced locally, used locally
- stimulates proliferation of epithelial cells
- primarily acts in tissue of origin
43
fibroblast growth factors
- family of 22 proteins that act on 4 different tyrosine kinase receptors
- stimulate fibroblasts and other cells!
44
insulin like growth factor 1
-released from the liver in response to growth hormone
45
vascular endothelial growth factor
| **********
- VEGF
- produced by cells that stimulate vasculogenesis and angiogenesis
- new blood vessel formation
- important for wet AMD
46
nerve growth factor
-stimulates the growth and differentiation (BUT NOT MITOSIS) of postganglionic sympathetic neurons
47
what leads to cancer?
| *********
-unregulated cell cycle
48
six hallmarks of cancer
- cell growth and division absent of proper signals
- continuous growth contrary to signals
- avoidance of apoptosis
- limitless cell division
- promoting blood vessel construction
- invasion of tissue
49
oncogenes
| ********
- mutated NORMAL genes
- encode POSITIVE cell cycle regulators
- mutated and stimulated all the time
50
Tumor suppressor genes
| ********
- genes that encode for NEGATIVE cell cycle regulators
| - stops the cell cycle
51
mutated p53
-does not detect mutations and does not stop cell cycle
