Endomembrane System (L5)

Question 1

Is a membrane system interconnected by direct physical contact or transfer by vesicles.

Answer 1

Endomembrane system

Question 2

What are the 3 main organelles responsible for moving proteins out of the cell?

Answer 2

Endoplasmic reticulum. Golgi apparatus. Vesicles.

Question 3

What is the Endoplasmic reticulum? What are its functions?

Answer 3

Is an organelle composed of two regions the sER and rER.

sER - synthesises lipids for membranes, metabolises carbohydrates, and stores calcium ions.

rER - where ribosomes are. synthesises proteins.

• secreted membrane proteins also enter the rER to be processed and released out or retained within the cell.

Question 4

What is the function of the Golgi complex/apparatus?

Answer 4

Receives, modifies, sorts and ships out proteins arriving form rER (kind of like the courier of the cell)

• glycolysylation (modification)
• sorts proteins via molecular markers (directs proteins)
• directs vesicle trafficking via molecular markers
• molecular markers are short proteins

Question 5

A series of membrane sacs and associated vesicles.

Answer 5

Golgi apparatus.

Question 6

Where does the synthesis of cytoplasmic proteins in the rough ER occur?

Answer 6

Free ribosomes

Question 7

What is the purpose of the golgi apparatus’ polarity?

Answer 7

Polarity means it has 2 sides: vesicles arrive at the cis face. And processed vesicles arrive at the trans face.

Question 8

Addition/modification of carbohydrates to proteins.

Answer 8

Glycosylation (in the golgi)

• important for secreted proteins

Question 9

Are membrane bound cytoplasm fluid filled organelles.

Answer 9

Vesicles

Question 10

What are the types of vesicles? (4)

Answer 10

• Transport vesicles
• Secretory vesicles
• Vacuoles
• Liposomes

Question 11

T/F: The amount of sER in a cell is fixed.

Answer 11

False. It changes based on the needs of the cell to carry out functions.

Question 12

T/F: The vesicles leave from the trans face of the golgi complex.

Answer 12

True. Vesicles enter through cis face; leave through trans face.

Question 13

How does bulk transport occur across the plasma membrane?

Answer 13

Exocytosis - which transports material using glycoproteins out of the cell into the cell surface.

Question 14

What is the difference between constitutive exocytosis and regulated exocytosis?

Answer 14

CE - releases extracellular matrix proteins (contributes to the ECM). Happens more freely

RE - releases hormones and neurotransmitters. Requires a signal to prompt release of a substance

Question 15

What are the modes of bulk transport across the plasma membrane? (2)

Answer 15

Exocytosis (constitutive - contributes to ECM by releasing ECM proteins. regulatory - prompted release of neurotransmitters and hormones)

Endocytosis (phagocytosis - cell eating/uptake of food particles. Pinocytosis - cell drinking/uptake of extracellular fluid. Receptor mediated endocytosis - specialised form of pinocytosis - requires receptor proteins.)

Question 16

Membrane bound organelles made by the rER that contain hydrolytic enzymes. They degrade macromolecules and release breakdown products into the cell.

Answer 16

Lysosomes.

Question 17

What is autophagy?

Answer 17

When lysosomes digest and recycle unwanted cellular materials

Question 18

These are large vesicles commonly found in plant cells. It absorbs water allowing plant cells to grow.

Answer 18

Vacuoles.

Question 19

Why is the inside of a lysosome acidic?

Answer 19

Because it is needed for enzymes to be active. These enzymes help to breakdown macromolecules and release by-products into the cell.