Lecture 7

Question 1

What is the endomembrane system?

Answer 1

A functionally integrated cellular unit.

Question 2

What are the functions of Smooth ER? (4)

Answer 2

METABOLISM of carbohydrates
Lipid SYNTHESIS for membranes
DETOXIFICATION of drugs/poisons
STORAGE of calcium ions

There are a lot of sER in cells that undergo the above processes heavily. The number of sER can be increased or decreased to meet demand.

Question 3

What are the functions of Rough ER (4) + note

Answer 3

Involved in PROTEIN SYNTHESIS
Secreted and Intergrator Proteins will enter the Lumen (interior of rER) and be process via the endomembrane system.

• rough due to the ribosomes.

Special note - synthesis of cytoplasmic proteins are on the free ribosomes (not bound to anything)

Question 4

What is the correct order to flow of particles through the endomembrane system OUT?

Answer 4

rER, Vesicle, Golgi

Question 5

What are the properties of the Golgi Complex?

Answer 5

Consists of membranous sacs & associated vesicles

Has polarity, cis and trans faces.

Question 6

Which side of the Golgi to vesicles form the ER enter?

Answer 6

Cis face

Question 7

Which side of the Golgi to vesicles leave from?

Answer 7

Trans face

Question 8

What are the roles of the Golgi? (3)

Answer 8

Glycosylation of proteins (attaching sugars to proteins)

Sorting proteins (adding molecular markers to direct 
proteins to the right destinations)

Directing vesicle trafficking (adding tags to direct vesicles to correct target compartments)

Question 9

What do the two types of retrieval tags do, and why are they important?

Answer 9

1. Directs proteins back to ER or Golgi
   Important as to maintain compartment integrity and function
2. Direct to secretory pathways
   Important for the vesicles that need to be release or for surface expression.

Question 10

Exocytosis does what?

Answer 10

It TRANSPORTS material out of the cell, DELIVERS materials to the cell surface.

Question 11

What are the two types of exocytosis?

Answer 11

Regulated Exocytosis

Constitutive Pathway

Question 12

What does the constitutive pathway release?

Answer 12

The release of proteins that make the ECM out of the cell.

Question 13

What does the regulated exocytosis release?

Answer 13

Releases hormones and neurotransmitters

Question 14

What are the three types of Endocytosis?

Answer 14

1. Phagocytosis -the uptake of ‘food’ particles. Forms a phagocytic vacuole.
2. Pinocytosis - the non-selective uptake of solutes
3. Receptor Mediated Endocytosis - collects and concentrates specific molecules.

Question 15

Endocytotic pathways are directed to……

Answer 15

The endosome-lysosome pathway

vacuole comes in, fuses with lysosome, lysosome digests the bacteria

Question 16

How does the lysosome know which vesicles to digest or not?

Answer 16

This is determined by the tags that the Golgi has put on them.

Question 17

What 3 types of things do lysosomes digest?

Answer 17

1. Cellular material - they contain enzymes that can degrade proteins, lipids, nucleic acids, carbohydrates
2. Endocytosed material
3. Unwanted intracellular structures (replacing old with new) they use the components from old structures to create new.

Question 18

Why are lysosomes important? (2)

Answer 18

It is because they are important for CELL HEALTH as well as in the case of CELL DESTRUCTION , AUTOPHAGY (programmed cell death)