Endomembrane System and Bulk Transport Processes

Question 1

What is included in the endomembrane system? (7)

Answer 1

• nuclear envelope
• endoplasmic reticulum ( smooth + rough)
• Golgi apparatus
• vesicles
• lysosomes
• vacuoles
• plasma membrane

Question 2

What is the endoplasmic reticulum?

Answer 2

A series of flattened sacs, and tubules connecting them, including two components: smooth and rough

Question 3

What are the functions of the smooth endoplasmic reticulum? (4)

Answer 3

• metabolism of carbohydrates
• Lipid synthesis for membranes
• Detoxification of drugs and poisons
• Storage of calcium ions

Question 4

What are the functions of the rough endoplasmic reticulum?

Answer 4

• involved in protein synthesis
• secreted and membrane-bound proteins enter the lumen of the rER and are processed by rER and then rest of the endomembrane system for release from cell

Question 5

What is the golgi complex?

Answer 5

series of membrane sacs and associated vescicles

Question 6

What are the functions of the Golgi Complex?

Answer 6

• receives, modifies, sorts and ships proteins from rough ER

Question 7

What are some key details about the Golgi complex?

Answer 7

• has polarity ( trans and cis face)
• vesicles from rER arrive at cis face
• processed vesicles leave the trans face

Question 8

What is Glycosylation? (golgi complex)

Answer 8

• addition or modification of carbohydrates into proteins

- important for secreted or cell surface proteins

Question 9

How does the golgi complex sort proteins?

Answer 9

• adds molecular markers to direct proteins to the correct vesicles before “budding” from trans face

Question 10

How does the Golgi Complex direct vesicle trafficking?

Answer 10

• adds molecular tags to vesicles leaving the trans face to direct them to the correct targets
• tags are often short proteins exposed on the vesicle surface
• Act as docking sites when they reach their targets

Question 11

What are the two types of exocytosis?

Answer 11

• Constitutive exocytosis

- Regulated exocytosis

Question 12

What does constitutive exocytosis do?

Answer 12

releases extracellular matrix proteins

Question 13

What does regulated exocytosis do?

Answer 13

• releases hormones and neurotransmitters

Question 14

What is endocytosis?

Answer 14

The uptake of molecules and particulate matter at the plasma membrane

Question 15

What are the 3 types of endocytosis?

Answer 15

• phagocytosis
• pinocytosis
• receptor mediated endocytosis

Question 16

What is phagocytosis and what are the key details?

Answer 16

• cell eating
• uptake of “food” particles
• forms a phagocytic vacuole which is “digested” by lysosomes

Question 17

What is pinocytosis and what are the key details?

Answer 17

• Cell “drinking”
• uptake of extracellular fluid containing various solutes such as proteins and sugars
• up-take vesicle is formed with the aid of a coat protein
• up-take in non selective

Question 18

What is receptor-mediated endocytosis and what are the key details?

Answer 18

• specialized form of pinocytosis
• allows the cell to take up bulk quantities of specific substances which may only be present at low concentrations in the extracellular fluid.
• receptor proteins are used to selectively capture the required solute

Question 19

What are lysosomes?

Answer 19

Membrane bound organelles made by rER and golgi body that contain hydrolytic enzymes

Question 20

What are the features and functions of lysosomes?

Answer 20

• acidic interior to aid with digestion
• degrade proteins, lipids, carbohydrates, and nucleic acids and release breakdown products into cell
• digest and recycle unwanted materials in process called autophagy

Question 21

What are vacuoles and what are the key features?

Answer 21

• large vesicles derived from rER and Golgi

- food vacuoles are involved in phagocytosis