The Endoplasmic Reticulum And Secretory Pathways

Question 1

What are the functions of the endoplasmic reticulum?

Answer 1

RER= protein synthesis, glycosylation (attaching carbohydrates to proteins or lipids) and folding of multi protein complexes

SER= lipid synthesis and detoxification by cytochrome P450 enzymes

Question 2

Fill in the blank: The rough endoplasmic reticulum is studded with _______.

Answer 2

ribosomes.

Question 3

What are the two types of endoplasmic reticulum?

Answer 3

Rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).

Question 4

Which type of endoplasmic reticulum is primarily involved in lipid synthesis?

Answer 4

Smooth endoplasmic reticulum (SER).

Question 5

Multiple Choice: What is the role of the rough endoplasmic reticulum?

Answer 5

A) Synthesize proteins B) Store calcium C) Lipid metabolism D) Detoxification

Question 6

What is the function of the smooth endoplasmic reticulum?

Answer 6

The smooth endoplasmic reticulum is involved in lipid synthesis, metabolism of carbohydrates, and detoxification.

Question 7

Fill in the blank: The endoplasmic reticulum is connected to the _______.

Answer 7

nuclear envelope.

Question 8

What is the significance of the cisternal space in the endoplasmic reticulum?

Answer 8

The cisternal space is where protein folding and modification occur.

Question 9

What are signal sequences and their role in protein synthesis?

Answer 9

Signal sequences= protein region that directs proteins to the correct cellular component

These are located at the N-Terminal end of a protein

Question 10

Describe the process of protein synthesis and modification in the rough endoplasmic reticulum.

Answer 10

1) firstly the proteins are broken down into amino acids or polypeptides (proteolysis or signal peptide)

2) then disulfide bonds form.

3) sugars are added to proteins as they enter the ER (glycosylation)

4) The sugars then detach from the proteins (deglycosylation)

5) protein folding and assembly in the Golgi apparatus

Question 11

True or False: The Golgi apparatus is involved in the modification and sorting of proteins synthesized in the endoplasmic reticulum.

Answer 11

True.

Question 12

Fill in the blank: Proteins are transported from the endoplasmic reticulum to the Golgi apparatus in _______.

Answer 12

Transport vesicles.

Question 13

Multiple Choice: What is the main destination for proteins after they leave the Golgi apparatus?

Answer 13

A) Cytoplasm
B) Lysosome
C) Plasma membrane
D) All of the above

Question 14

Explain the pathways of vesicular transport

Answer 14

Vesicles transport proteins:
1) from Golgi apparatus to lysosomes, the plasma membrane or the exterior

2) from plasma membrane to lysosomes

3) from endosomes to plasma membrane

Endosomes= membrane bound organelle which is involved in sorting and recycling of materials

Question 15

What role do vesicles play in the secretory pathway?

Answer 15

Vesicles transport proteins from the endoplasmic reticulum to the Golgi apparatus and from the Golgi to their final destinations.

Question 16

Explain the budding-movement- fusion.( Pathways of vesicular transport)

Answer 16

This refers to how proteins and lipids are transported within cells.

Budding:
The vesicles ‘bud off’ from the Golgi apparatus, carrying their cargo to another organelle.

Movement:
The vesicles then travels through the cell to its destination
-coat proteins (e.g. COPI AND COPII) help the vesicles move along microtubules.

Fusion:
-vesicle membrane fuses with the target membrane.
v-SNARE binds to t-SNARE (V-SNARE= vesicle protein and T-SNARE= target membrane).
The transport vesicle fuses to the target membrane and cargo is delivered