Membrane Structure, Lipids/Proteins

Question 1

What are the two major groups of membrane proteins?

Answer 1

• -membrane proteins(integral): embedded in the membrane and are covalently bound to other proteins
• -membrane-assoicated proteins(peripheral): proteins that are non-covalently associated with proteins

Question 2

Why are porins in bacteria important clinically?

Answer 2

-Porins allow material like nutrients through the membrane to get to the plasma membrane for cells. They also allow antibiotics to get through.
Hence gram negative bacteria can naturally be more resistant to antibiotics. This is because antibiotics cannot get across the membrane unless the porins permit them to go through. So if an antibiotic that cant get through the specific porins of the gram-negative bacteria, the bacteria becomes resistant

Question 3

What is the difference between glycoproteins and proteoglycan?

Answer 3

• glycoproteins are proteins with carbohydrates attached to them (oligosaccharide chains)
• proteoglycan are also proteins with carbohydrates attached to each other except with a longer carbohydrate chains (polysaccharides)

Question 4

where does glycosylation of membrane proteins happen?

Answer 4

-ER and the Golgi (a lot of membrane proteins coming out of these will be glycosylated)

Question 5

how may membrane proteins restricts movement of proteins in the cell?`

Answer 5

• some membrane proteins can link up in the cytoskeleton; this restricts movement of membrane proteins and they will only move is the cytoskeleton moves
• corralling is another restriction: proteins form attachments with the cytoskeleton and associated proteins to form “fences”

Question 6

True or False: membrane proteins are critical to the shape of the membrane

Answer 6

true

Question 7

What is the most abundant phospholipid?

Answer 7

Phosphoglycerides

Question 8

What is the main structure of Phosphoglycerides?

Answer 8

a) 3-carbon glycerol backbone
b) 2 C in glycerol bind fatty acids by ester bonds
a) 3rd carbon in glycerol is linked to phosphate
b) phosphate linked to head group

Question 9

What is the main structure of sphingosine?

Answer 9

a) 1 sphingosine backbone (1 amino group and 2 hydroxyl groups) instead of glycerol
b) fatty acid attached to the amino group and polar head group

Question 10

True or False: some sphingolipids are phospholipids

Answer 10

TRUE

Question 11

What is the general structure of sterols?

Answer 11

All steroids have a 4 carbon ring with a hydroxyl group at one end. Cholesterol has the hydroxyl group on the first carbon ring

Question 12

What are glycolipids and what the two types?

Answer 12

Glycolipids are lipids with carbohydrates attached to them. The two types are either a glycerol backbone or sphingosine

Question 13

What is the function of glycolipids?

Answer 13

Protect the membrane from harsh conditions
Alter the electrical field across the membrane due to the charged sugars
Helps to concentrate Ca2+ on the outer membrane
Cell recognition
Provide the entry point for bacterial toxins and viruses