Physiology part 2

Question 1

What does the plasma membrane control?

Answer 1

The entry of nutrients and exit of waste and products

Question 2

What does the plasma membrane maintain?

Answer 2

Differences in ion concentration inside and outside the cell

Question 3

What does the plasma membrane participate in?

Answer 3

Joining of cells to form tissues and organs

Question 4

What does the plasma membrane enable?

Answer 4

Enables a cell to respond to changes in the environment

Question 5

What are functional differences between cells due to?

Answer 5

Composition of their plasma membrane

Question 6

What are the two principle constituents of the plasma membrane?

Answer 6

Lipid and protein

Question 7

What is the membrane primarily composed of?

Answer 7

Phospholipids 
Head(negatively charged, hydrophilic)
Tail (uncharges, hydrophobic)

Question 8

What structure do phospholipids form in fluid?

Answer 8

Bilayer

Question 9

Describe the bilayer

Answer 9

Fluid, not rigid (cooking oil, not lard)

Phospholipids are constantly moving;
(twirl, vibrate and move around their own half of the membrane millions of time per second)

Question 10

What is the role of cholesterol in the membrane?

Answer 10

Aids in the stiffening

Can easily flip leaflet

Question 11

Name three common membrane lipids?

Answer 11

Phosphatidylinositol
Phosphatidylserine
Phosphatidlycholine
Shingomyelin
Galactocerebroside
Cholesterol

Question 12

What is the bilayer impermeable to?

Answer 12

Charged molecules

Question 13

What can cross the membrane fairly freely?

Answer 13

Small uncharged polar molecules

Question 14

What are the three most important functions of the lipid bilayer?

Answer 14

1) forms the basic structure of the membrane.

2) hydrophobic interior serves as a barrier
>cell can maintain differences in solute composition and concentrations inside/outside the cell

3) responsible for fluidity of the membrane
>Enables cells to change shape (e.g. RBC or a skeletal muscle cell)

Question 15

What are the two broad classes of membrane proteins?

Answer 15

Peripheral or integral

Question 16

Describe peripherally associated membrane proteins?

Answer 16

Not embedded within the membrane

Adhere tightly to the cytoplasmic or extracellular surfaces of the PM

Question 17

What are the three ways integral proteins can be associated?

Answer 17

Span the membrane several times- transmembrane

Embedded but do not cross

Linked to lipid component of the membrane or a fatty acid derivative that intercalates to the membrane

Question 18

How are peripheral proteins bonded?

Answer 18

Non-covalently bonded with integral proteins

Question 19

How are integral proteins that do not span the membrane bonded?

Answer 19

Via ogliosaccharide

OR

directly linked to a fatty acid or prenyl group

Question 20

What are the functions of integral membrane proteins?

Answer 20

Ligand-binding receptors

Adhesion molecules

Pores and channels

Carriers

Pumps

Enzymes

Intracellular signalling

Question 21

Which receptors are ligand-binding receptors?

Answer 21

Hormone receptors

Question 22

What do adhesion molecules do?

Answer 22

form physical contacts with the surrounding extracellular matrix or cellular neighbours

Question 23

What are adhesion molecules important for?

Answer 23

Regulating cell shape, growth and differentiation, allowing cell to adapt to surroundings

Question 24

Give two examples of adhesion molecules

Answer 24

Integreins: cell matrix adhesion molecules

Cadherins: bind glycoproteins

Question 25

What is the role of pores and channels?

Answer 25

Conduits allow water and specific ions to flow passively through bilayer

Question 26

What is the role of carriers?

Answer 26

Either facilitate the transport of a specific molecule or couple the transport of a molecule to that of other solutes

Question 27

What is the role of pumps?

Answer 27

Use energy that is released through the hydrolysis of ATP to drive the transport of substances into or out of the cell against energy gradients

Question 28

Give examples of integral membrane enzymes?

Answer 28

Membrane bound enzymes in small intestine

Carbonic anhydrase

Question 29

Give examples of integral membrane proteins that participate in intracellular signalling and their location?

Answer 29

GTP-binding proteins
Kinases

Associated with cytoplasmic surface of PM

Question 30

What are docking marker acceptors?

Answer 30

Locates on inner membrane surface

Interact with secretory vesicles leading to exocytosis of the vesicle contents

Question 31

What is membrane carbohydrate?

Answer 31

small amount of membrane carbohydrate located on the outer surface of cells

Question 32

Where are short carbohydrate chains often bound?

Answer 32

To membrane proteins and to a lesser extent lipids

>glycoproteins and glyloclopods

Question 33

What do glycoproteins and glycolipids form?

Answer 33

The glycocalyx

Question 34

What do membrane carbohydrates serve as?

Answer 34

Self-identity markers that enable cells to identify and interact with each other

Question 35

What do-self identity markers prevent?

Answer 35

Cells overgrowing territory

Question 36

What are the three types of specialised cell junction?

Answer 36

Tight junctions

Desmosomes

Gap junctions

Question 37

Describe the tight junctions

Answer 37

Join lateral edges of epithelial cells near their lumenal membranes

Question 38

Describe desmosomes

Answer 38

Adhering junctions that anchor cells together, especially in tissues subject to stretching

Question 39

Describe gap junctions

Answer 39

Communicating junctions that allow the movement of charge carrying ions and small molecules between two adjacent cells

Question 40

Where are desmosomes found?

Answer 40

Skin, heart, uterus