Lecture 5: Cell adhesions and membrane trasnport

Question 1

What are the three ways cells are held together?

Answer 1

1. Cell adhesion molecules (CAM)
2. Extracellular matrix (ECM)
3. Specialized cell junctions

Question 2

What is the Extracellular matrix?

Answer 2

• meshwork of fibrous proteins in the interstitial fluid

Question 3

True of False interstitial provides a pathway for diffusion of nutrients, wastes, and other soluble traffic between the blood and tissue ?

Answer 3

true

Question 4

What are the three types of proteins found in the extracellular matrix?

Answer 4

• Collagen
• Elastin
• Fibronectin

Question 5

What does collagen do in respect to the ECM?

Answer 5

• forms cable like fibers
• gives tensile strength

Question 6

True or false
Collagen weights 1/2 the amount of the total body protein weight?

Answer 6

true

Question 7

What does elastin do in respect to the ECM?

Answer 7

• rubber like protein fiber
• allows stretching and and recoiling

Question 8

Would the lung have more elastin than the skin?

Answer 8

yes it’s need more for the stretch factor when breathing

Question 9

What does Fibronectin do in respect to the ECM?

Answer 9

• Promotes cell adhesion
• holds the cell in place

Question 10

Reduced levels of what is related to tumor metastasis?

Answer 10

Fibronectin

Question 11

Name the three types of specialized junctions and their main function:

Answer 11

1. Desmosomes - adhering
2. Tight Junctions - impermeable
3. Gap junctions - communication

Question 12

What is the function of the Desmosomes?

Answer 12

• anchors two cells together
  that provides two cells with the strongest form of adhesions

Question 13

How do desmosomes work?

Answer 13

• we add proteins called intercellular filaments which will connect the two cells together
• than we use intracellular keratin proteins to attach tp the plaque and weave through the entire cell
• the desmosomes are attached to both inter and intra cellular filaments

Question 14

In what kind of cell would we find lot’s of desmosomes?

Answer 14

uterus

Question 15

What is the function of Tight junctions?

Answer 15

for cells to have nothing in between them (sewing them together)
- created an impermeable barrier

Question 16

In what kind of cell would we find lot’s of tight junctions and where in our body ?

Answer 16

columnar epithelium cells, in the lining of the intestine

Question 17

What is the function of gap junctions?

Answer 17

for cells to communicate at an instantaneous rate

Question 18

In what kind of cell would we want gap junctions

Answer 18

• muscle cells
• heart / cardiac cells

Question 19

True or False?
Connecting tunnels are called connexons? (wheres ions go from one cell directly to another without crossing the extracellular space)

Answer 19

true

Question 20

What is permeability?

Answer 20

means molecules can pass freely a given membrane

Question 21

What is impermeability?

Answer 21

means molecules cannot pass freely though given membrane

Question 22

Are molecules either 100% soluble or non soluble?

Answer 22

no, generally they are somewhere in between

Question 23

What can pass easily through the plasma membrane?

Answer 23

• O2
• CO2
• Fatty acids
• anything lipid soluble
• non-polar molecules

Question 24

What cannot pass easily through the plasma membrane?

Answer 24

• ions
• proteins
• glucose

Question 25

does the size of a particle have an effect on the speed at which is crosses the plasma membrane?

Answer 25

yes

Question 26

What is active force?

Answer 26

forces that require the cell to expend energy

Question 27

What is passive force?

Answer 27

forces that do not require the cell to spend energy