Lecture 19 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Where does glycosylation occur

A

within the lumen of the ER and the Golgi complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the difference between the smooth and rough ER

A

Rough ER: contains ribosomes that produce/secretes proteins

Smooth ER: lacks ribosomes and is the primary site for lipid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the functions of the smooth ER (SER)

A

1) Lipid Synthesis (main function)

2) Production of steroid hormones (endocrine cells)

3) Detoxification: liver cells that contain enzymes that modify foreign compounds

4) Sequestration (storage) of Ca2+ [needed for muscle contraction/relaxation]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the functions of the rough ER (RER)

A

1) Synthesis of membrane phospholipids

2) Glycosylation of proteins (addition of carb chains to specific proteins)

3) Protein folding (quality control) - molecular chaperones that help with the folding process

4) Protein synthesis, modification, and transport - proteins targeted to ER, endocrine compartments and plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where does protein synthesis occur? What is the main function?

A

Occurs in the cytoplasm

ribosomes synthesize polypeptides from mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What proteins/organelles are associated with translation of free ribosomes?

A

Cytosolic proteins
Peripheral membrane proteins
Proteins targeted to the nucleus, mitochondria, peroxisomes and chloroplasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What proteins/organelles are related to ribosomes associated with the ER membrane

A

Secreted proteins
integral membrane proteins
soluble proteins associated with the lumen of the endomembrane system
(e.g ER, Golgi, lysosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is the site of translation determined?

A

Ribosomes are targeted to the ER membrane by a specific signal sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the signal sequence for the site of translation

A

Is located in the amino-terminus (N-terminus)
Contains several consecutive hydrophobic amino acids
Directs synthesis to the ER compartment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why does a protein move through a channel and into the ER

A

For cotranslational import

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the steps of cotranslational protein import

A

1) after translation of the signal sequence, a signal recognition particle (SRP) binds to the sequence and stops translation

2) SRP binds to the SRP receptor and targets the whole translation complex to ER (SRP + ribosome + mRNA + new polypeptide)

3) SRP gets released adn the ribosome binds to the translocon, protein synthesis resumes

4) The polypeptide enters the ER through translocon and is translated. Signal peptide is cleaved off and the chaperone folds the protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is exocytosis

A

movement of cellular components to the plasma membrane

Through the biosynthetic/secretory pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is endocytosis

A

movement of cellular components from the plasma membrane to an organelle (lysosome)

Through the endocytic pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an example of exocytosis

A

Secretion of a neurotransmitter from pre-synaptic neuronal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an example of endocytosis

A

Uptake of low density lipoprotein (LDL - in the blood contains cholesterol to make membranes) particle in liver cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly