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Biochemistry Pt. 3 > Biochemistry - Membrane Lipids > Flashcards

Biochemistry - Membrane Lipids Flashcards

1
Q

Are sphingolipids amphiphatic?

A

Yes.

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2
Q

Describe the basic structure of glycerophospholipids.

A

Glycerol backbone usually with a saturated FA on C1, and unsaturated FA on C2, and an alcohol group on C3 via a phosphodiester linkage.

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3
Q

What is cardiolipin and where is it found?

A

It is a glycerophospholipid with two phosphate groups and is commonly found on mitochondrial membranes.

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4
Q

Which membrane (outer vs. inner) is phosphatidyl choline (PC) usually found?

A

Outer.

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5
Q

Which membrane (outer vs. inner) is phosphatidyl ethanolamine (PE) usually found?

A

Inner.

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6
Q

Which membrane (outer vs. inner) is phosphatidyl serine (PS) usually found?

A

Inner.

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7
Q

Which glycerophospholipid, when found on the outer membrane, is a potent signal for apoptosis?

A

Phosphatidyl serine (PS)

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8
Q

What is unique about glycerophospholipids found in lung alveoli?

A

The C2 FA is saturated to prevent alveolar collapse.

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9
Q

Which glycerophospholipids can be interconverted?

A
  1. PE to PS (only way in humans to make PS).

2. PE to PC via methylation

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10
Q

What is a plasmalogen? What are two important functions of these molecules?

A

A glycerophospholipid with a fatty alcohol in an ETHER linkage at C1.

Functions:

  1. Platelet-activating factor is a plasmanyl (no double bonds vs plasmenyl has 2x bond)
  2. Found on the mitochondrial inner membrane because they are resistant to oxidative damage that could potentially hydrolyze ester bonds.
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11
Q

What do phospholipases do?

A

They cleave bonds of glycerophospholipids to create signaling molecules.

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12
Q

What do PLA2s do?

A

Cleave PUFAs off glycerophospholipids. The PUFAs are then acted upon by oxygenases to create intercellular signaling molecules.

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13
Q

Are PLAs found in venom? What cells do they mess with?

A

Yeah. They act as hemolytic detergents against RBCs.

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14
Q

Name an important FA that is involved in intercellular signaling via phospholipase A2s.

A

Arachidonic acid.

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15
Q

What enzyme acts upon arachidonic acid to generate prostaglandins?

A

Cyclooxygenase

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16
Q

What two important chemical changes occur when arachidonic acid is reacted to form prostaglandins by cycloxygenase?

A

Double bonds are lost and a cyclic molecule is the result.

17
Q

What does the “2” in prostaglandin G2 indicate?

A

It indicates the remaining number of double bonds (arachidonic acid, its precursor, has 4 double bonds)

18
Q

What do lipooxygenases do? What chemical change occurs?

A

Make leukotrienes from arachidonic acid. Peroxide is added (note: no change in double bonds)

19
Q

What does the “5” in 5-lipooxygenase mean?

A

It indicates which carbon will have the peroxide added.

20
Q

What are the three places lipooxygenases can add peroxides to arachidonic acid?

A

5, 12, 15

21
Q

Are leukotrienes linear molecules?

A

Yes.

22
Q

How are PIPs created?

A

Phosphorylation (by a kinase) of phosphatidyl-inositol.

23
Q

What do PLCs do?

A

They cleave IPs (inositol phosphates) off phosphatidyl inositol WITH the phosphate group.

24
Q

What does IP3 do?

A

It is a second messenger molecule that results in release of Ca2+ from the ER, activating protein kinase C and calmodulin kinase.

25
Q

What important membrane lipid is a crucial component of the myelin sheath? What else is special about this molecule?

A

Sphingomyelin. It is the only sphingolipid with a phosphate group.

26
Q

What is multiple sclerosis?

A

Autoimmune disease results in demyelination in the CNS.

27
Q

What molecule serves as the backbone of a sphingolipid?

A

Ceramide.

28
Q

What is the structure of a glycolipid?

A

Ceramide backbone with an ester linkage to glucose (resulting in a globoside) or galactose (resulting in a sulfatide).

29
Q

What is a ganglioside?

A

A glycolipid (ceramide + sugar) + neuramic acid (it is a charged molecule)

30
Q

What is the enzymatic defect in Tay Sachs, and what builds up?

A

Hexosaminidase A deficiency results in GM2 build-up.

31
Q

What two membrane molecule classes are involved in cellular recognition (such as the blood-group antigens)?

A

Gangliosides and globosides.

32
Q

What lipids are used for protein anchoring on the cytoplasmic side of the cell?

A

Palmitate, myristate, and farsenine.

33
Q

What lipid is used for protein anchoring on the ectoplasmic side of the cell?

A

GPI anchor

34
Q

Which glycerophospholipids are made via head group activation (vs. DAG activation)?

A

PE, PC

35
Q

Which enzyme does aspirin inhibit?

A

Cyclooxgenase.

Biochemistry Pt. 3 (6 decks)

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