Chapter 6.1.2 + 6.2 (Exam 1) Membranes

Question 1

Are biological membrane proteins stuck in one place?

Answer 1

No, some membrane proteins can move freely and diffuse across the entire membrane bilayer

Question 2

Membranes are dynamic. What does this mean, and what is one example of this in our own cells?

Answer 2

Membranes are constantly forming, transforming, fusing, and breaking down

The endomembrane system–vesicles pinch off the RER to transport molecules such as precursor proteins to the GA to be cut

Question 3

How do membranes adhere to and recognize other cells and molecules?

Answer 3

Membranes have carbohydrates and proteins on the outer surface that serve in adhesion and as recognition sites for other cells and molecules

Question 4

What are glycolipids?

Answer 4

Carbohydrates + lipids

Question 5

What are glycoproteins?

Answer 5

carbohydrates (oligosaccharides) + proteins

Question 6

What is the difference between proteoglycans and glycoproteins?

Answer 6

Proteoglycans have a higher percentage of carbohydrates

Question 7

What are cell junctions? What are the three types?

Answer 7

Cell junctions are specialized structures that hold cells together

Tight junctions

Desmosomes

Gap junctions

Question 8

What is the function of tight junctions?

Answer 8

Tight junctions help ensure directional movement of materials and hold cells together

Question 9

What is the function of desmosomes?

Answer 9

Desmosomes function like “spot welds” to hold cells together

Question 10

What is the function of gap junctions? What is one example of this?

Answer 10

Gap junctions allow communication and hold cells together

E.g. neuron gap junctions allow ion flow to transmit APs