Cell biology: Organelles Flashcards
1
Q
All cyclins are degraded by what
A
Ubiquitine protein ligase
2
Q
What binds to and inactivates Cyclin-CDK complexes
A
- p21
- p27
- p57
3
Q
What controls the transcription of p21
A
p53
4
Q
Describe how Cyclin D/CDK4 control progression from G1 to S phase
A
- Cyclin D binds/activates CDK4
- Phosphorylation of Rb protein
- Rb protein is released from transcription factor E2F
- with E2F unbound, the cell is free to transcribe/synthesize components needed for progression through the S phase (cyclin E, DNA polymerase, thymidine kinase, DHF reductase)
5
Q
Cyclin B-CDK1 complex is activation by what?
A
cdc25
6
Q
activated cyclin B-CDK1 complex leads to breakdown of what?
A
nuclear lamins and initiation of mitosis
7
Q
What is used in the trafficking through Golgi?
Describe it
A
- COP-II: anterograde trafficking from rough ER to Golgi
- COP-I: retrograde from Golgi back to rough ER
- Clathrin: Far side of Golgi (trans) –> brings hydrolases to lysosomes
8
Q
Describe the post-translational modification of protein and proteoglycans by the Golgi
A
- Glycosylation of core proteins to form Proteoglycans
- Sulfation of proteoglycans and selected TYROSINE residues
- add O-oligosaccharides to SERINE and THREONINE
- adds mannose-6-phosphate to ASPARGINE residues located on Lysosomal enzymes
9
Q
This is a deficiency in Mannose phosphorylation by Golgi. so lysosomal proteins get secreted out of the cell instead of into lysosomes
A
I-cell disease
10
Q
Describe I-cell disease
A
- Death by age 8
- Corneal clouding
- coarse facies
- hepatosplenomegaly
- skeletal abnormalities
- restricted joint movement
- May have intellectual disability
11
Q
Describe the function of Peroxisomes
A
- Beta-oxidation of VERY LONG chain fatty acids and branched chain fatty acids
- **Synthesis of Plasmalogens (important phospholipids found in myelin)
- Oxidases and catalase for metabolizing ethanol (and other toxic substances)
