KINE 2P09: LECTURE TWO

Question 1

What is a cellular membrane?

Answer 1

Also called the plasma membrane, it is found in all cells and separates the interior of the cell from the outside environment.

Question 2

what makes the membrane composition

Answer 2

proteins, lipids, and carbohydrates

Question 3

define membrane function

Answer 3

Regulates the transport of materials entering and exiting the cell.

Question 4

mechanisms used to link cells together

Answer 4

Gap junctions, tight junctions, and desmosomes.

Question 5

two classes of membrane proteins

Answer 5

1. Integral membrane proteins
2. Peripheral membrane proteins

Question 6

what do Integral membrane proteins do

Answer 6

They are closely associated with the membrane lipids and cannot be extracted from the membrane without disrupting the lipid bilayer. (They are amphipathic)

Question 7

Peripheral membrane proteins

Answer 7

1. Are not amphipathic
2. do not associate with the lipids’ nonpolar regions in the membrane’s interior.
3. They are located at the membrane surface, bound to the polar regions of the integral membrane proteins.

Question 8

Typical Transmembrane Protein

Answer 8

1. Cholesterol
2. Glycoproteins/glycolipids

Question 9

Integrins

Answer 9

Transmembrane proteins bind to specific proteins in the extracellular matrix and link them to membrane proteins on adjacent cells.

Question 10

Desmosomes

Answer 10

The region between two adjacent cells where the apposed plasma membranes are separated by about 20 nanometers.

Question 11

Characterized by accumulations of protein known as ____ along the cytoplasmic surface of the plasma membrane.

Answer 11

dense plaques or Neighboring cells

Question 12

____ are proteins that extend from the cell into the extracellular space, linking up and binding with ____ from an adjacent cell.

Answer 12

Cadherins

Question 13

Tight Junctions

Answer 13

form when the extracellular surfaces of two adjacent plasma membranes join together so that no extracellular space remains between them. (no gap between them)

Question 14

Tight junction forms….

Answer 14

Barriers that limit the movement of material between cells (for example epithelium lining the gut and bladder).

Question 15

Gap junctions

Answer 15

consist of protein channels linking the cytosols of adjacent cells

Question 16

connexins

Answer 16

The two membranes join, forming small, protein-lined channels linking the two cells.