Lecture 8 Flashcards
(32 cards)
1
Q
Groups of the Endomembrane system
A
- Endoplasmic Reticulum
- Golgi Apparatus
- Endosomes
- Lysosomes
- Peroxisomes
2
Q
General functions of Endomembrane system
A
- Regulate protein trafficking
- Metabolism
3
Q
Top 3 percentage of volume in the cell
A
- Cytosol
- Mitchondria
- Endoplasmic Reticulum
4
Q
Two types of vesicle transport
A
- Budding
- Fusion
5
Q
Budding
A
- Bud from donor membrane compartment
- Move via motor proteins
6
Q
Fusion
A
Fuse with membrane of acceptor compartment
7
Q
Pathways of the Endomembrane system
A
- Biosynthetic pathway (secretory pathway)
- Endocytic pathway
8
Q
Biosynthetic Pathway
A
- Proteins are synthesized in the ER
- Packaged in Golgi
- Transported to various destinations
9
Q
Endocytic pathway
A
- Materials moves from outer surface of cell compartments
10
Q
Constituive secretion
A
- Materials are transportes in secretory vesicles
- Discharged continuously
- Formation of ECM, plasma membrane
11
Q
Regulated secretion
A
- Materials stored / secreted in secretory granules
- Discharged in response to stimulus
- Pancreatic enzymes
- Controlled
- Neurotransmitters
12
Q
Difference between constitutuve vs Regulated
A
Vesicles vs Granules
13
Q
Endoplasmic Reticulum
A
- Continuous with membrane of nuclear envelope
- Synthesis of most lipids and proteins
14
Q
What does the ER consist of
A
- Sac like sheets
- Branched tubules
- Cisternae space
15
Q
Rough ER
A
- Bound ribosomes
- Helicoidal membranes connect cisternae
- Continuous with nuclear envelope
16
Q
Smooth ER
A
- No ribosomes
- Highly tubular network
- Contunuous with Rough ER
17
Q
Main functions of Smooth ER
A
- Steroid hormones synthesis in endocrine cells
* Gonads
* Adrenal Cortex - Detoxification of the liver
- Calcium ion sequestration, regulated release in muscle cells (sarcoplasmic reticulum)
18
Q
Main function of Rough ER
A
Protein synthesis
19
Q
2 main locations of ribosomes
A
- Rough ER
- Cytosol
20
Q
Proteins from free polyribosomes go to
A
- Mitochondria
- Nucleus
- Peroxisomes
21
Q
ER proteins go through
A
Co - Translational translocation
22
Q
Signal Sequence
A
- 6 to 15 hydrophobic amino acid residues
- Directs nascent polypeptide + ribosome to ER membrane
23
Q
Signal Recognition Particle
A
- Recognizes signal sequence
- Binds polypeptide + ribosome = Arrests synthesis
- Complex recruited ER membrane
- SRP receptor binds with SRP
- Translocon binds to polypeptide
- Polypeptide synthesis resumes
- Co translational translocation deposits protein to ER lumen
24
Q
SRP and SRP are ____ proteins
A
G
25
Signal Peptidase
- Removes signal sequence
26
How is glycocalyx formed
- Glycotranferases: Add sugars to oligosaccharides
- Each transfers a specific monosaccharide
27
Pre assempled block of N - Glycosylation is tranferred by ER enzyme
Oligosaccharyltransferase
28
Oligosaccharyl Transferase is binded to
Aspargine
29
Many proteins are Glycosylated by _____ residues on the ER
Asparagine
30
Quality control protein for Glycocylation
- UGGT or UDP
31
What happens to misfolded proteins
- Tagged with Glucose
- Mannose removal
- Transported to cytosol
- Destroyed by proteasomes in cytosol
32
BiP
- Molecular chapeorone helps proteins fold
- Relaease of BiP and accumulation of Bip self desructs ribosomes
