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BMS 100 Test 2 > Lipids: Fatty Acid Structure > Flashcards

Lipids: Fatty Acid Structure Flashcards

1
Q

Two main classes of lipids:

A

1) Fatty acids

2) Isoprenoid

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2
Q

Naming fatty acids:

2 naming conventions

A

1st naming convention

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3
Q

Naming fatty acids:

2 naming conventions

A

2nd naming convention

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4
Q

Unsaturated fatty acids:

A

Double bonds can be cis or trans.

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5
Q

Unsaturated fatty acid:
Cis

A

Creates a “bend” in the structure.

Naturally made fat

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6
Q

Unsaturated fatty acids:
Trans

A

Have tighter bonds and “straight”

Some are made naturally by the gut bacteria (meat products)

The rest are made commercially as a by-product of partial hydrogenation

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7
Q

What does the bend on a cis bond do to membrane fluidity?

A

The “bends” cause kinks in the aceyl chains of phospholipid bilayers of membranes causing the junctions to become loose. This increases membrane fluidity.

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8
Q

Partial hydrogenation targets cis-bonds in fatty acids to:

A

Add hydrogens and turn oils into solid fats.

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9
Q

How can partially hydrogenated fats be labelled as 0 trans fat?

A

Using reduced pressure and blending oil reduces the trans fat content.

Less than 0.5 grams per serving can be labelled as “0% trans fat.”

Associated with increased risk of coronary heart disease

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10
Q

Fatty acid synthesis:

A

Occurs in cytoplasm (16:0 palmitate)
Substrates: Acetyl CoA & malonyl CoA

(malonyl CoA= acetyl CoA w/ extra CO2 group)

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11
Q

Fatty acid synthase:

A

Enzyme for fatty acid synthesis:

Exists as a dimer (two fatty acid chains can be made at once)

Contains two S groups: one from cysteine, one from B5
(cis binds acetyl groups, and B5 binds malonyl groups)

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12
Q

B7: biotin:

A

Coenzyme of fatty acid synthesis:
helps add CO2 to acetyl CoA to make malonyl CoA (malonyl CoA)

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13
Q

B5:

A

part of fatty acid synthase:
also part of acetyl CoA and malonyl CoA

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14
Q

B3:

A

NADPH
reduces the fatty acid chain

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15
Q

Which pathway provides NADPH?

A

Pentose phosphate pathway

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16
Q

How do you get to a 16 carbon chain?

A

You repeat the elongation cycle.

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17
Q

How do you get the chain off the enzyme?

A

Use water to break the bond:
hydrolysis

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18
Q

How do you make the chain bigger than a 16C chain?

A

Elongate using enzymes embedded in the ER membrane.

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19
Q

How do you make odd-numbered fatty acid chains?

A

Starting with propionyl CoA (3C) rather than acetyl CoA (2C) in step one can make odd-numbered chains.

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20
Q

How do you get unsatturated fatty acids?

A

Some from the ER: desaturase enzymes use NAD (P) H (B3) to create double bonds

Some are essential, only get them from diet desaturase enzymes are only found in plants.

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21
Q

Essential fatty acids:

A

needed to support the cardiovascular, immune, reproductive, and nervous systems.

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22
Q

How do you regulate fatty acid synthesis?

A

Glucagon: released when blood sugar is low

Insulin: released when blood sugar is high

Epinephrine: released during sympathetic responses

-Synthesis is oppositely regulated to break down (beta ox)
-Synthesis promotes storage of fats as TG’s

23
Q

Glucagon promotes beta ox (and therefore decreases fatty acid synthesis)

A

Glucagon plays a crucial role in promoting beta-oxidation by increasing the availability of FFAs, removing regulatory barriers, and directly activating enzymes involved in the process. Provides the body with an alternative source of energy when glucose is limited.

24
Q

Inhibits acetyl CoA carboxylase:

A

Glucagon & epinephrine

25
Q

Activates acetyl CoA carboxylase:

A

Insulin

26
Q

Acetyl CoA carboxylase catalyzes:

A

It catalyzes the first committed step in fatty acid synthesis: the addition of bicarbonate to acetyl-CoA to make malonyl CoA.

27
Q

Triglycerides:

A

Three fatty acids are attached to a glycerol backbone via an ester linkage.

Provides energy and insulation.

28
Q

Which packs tighter? triglycerides of glycogen and why?

A

Triglycerides: because it is more hydrophobic than glycogen. Can attract more hydrophobic molecules and exclude water.

29
Q

Triglyceride synthesis:

A

Lipogenesis
liver and adipocytes: cytosol of cells

Starts with addition of 2 fatty acids to a glycerol backbone.

Makes substrates: glycerol -3- phosphate backbone, 3 fatty acyl CoAs.

Transfer 2 fatty acid chains to the backbone sequentially

Replace the phosphate on the backbone witht he 3rd fatty acid chain

30
Q

What enzyme adds a phosphate to glycerol?

A

Glycerol Kinase

31
Q

Adipose and liver convert DHAP from ______ to glycerol 3 phosphate using _________.

A

cytosol and mitochondria of cells

using glycerol 3 phosphate hydrogenase (GPDH)

32
Q

Fatty acids are added to a CoA carrier using _____

A

ATP

33
Q
A

A: Pyruvate
B: acetyl CoA
C: Polyphenol sulfide
D: pyruvate carboxylase
E: acetyl CoA
F: acetly coA carboxylase
G: NADPH; fatty acid synthesis, steroid hormone production

34
Q

Phospholipids & glycosphinolipids

A
35
Q

Phosphoglycerides:

A

Made: ER

First three steps: acylation of glycerol 3 phosphate, phosphorylation of diacylglycerol, attachment of a head group to phosphatidic acid

36
Q

Glycerol-3-P is made from ____ in liver and adipose tissue. Liver can also make it from______.

A

Pyruvate; DHAP

37
Q

Fatty acids are activated by attachment to a _____ carrier.

A

acyl carrier protein (ACP)

38
Q

_____ fatty acids are sequentially added to the glycerol 3 p

A

saturated fatty acids

39
Q

Adding the head group on a phospholipid:

A

First, a CMP is added to create a good leaving group

Next, the CMP is removed to add head group attached via nucleophilic substitution.

40
Q

Sphingolipids:

A

Sphingomyelin:

Phosphate-alcohol head group

Backbone= sphingosine (part of ceramide)

Has two fatty acid tails:
-one is sphingosine backbone
-One is added to sphingosine to make a ceramide

Found in cell membranes: important component of myelin

41
Q

Tay-Sach’s disease:

A

Glycosphingolipids

accumulation of sphingolipids

Accumulates lyssosomes due to an enzyme deficiency

Most severe excess occurs in the brain

Build up leads to neuronal damage: neurodegeneration can lead to death by 5 years of age.

42
Q

Eicosanoids: Derived from arachidonic acid or similar 20 C fatty acids

A

Include prostaglandins

Physiological functions depend on type:
-Vasodilation
-Vasoconstriction
-Platelet aggregation

43
Q

Waxes:

A

Mixtures of nonpolar molecules, including fatty acids linked to long-chain hydrocarbon alcohols via ester bonds

44
Q

Categories of isoprenoids:

A

1) Terpenes
2) Mixed terpenes
3) Steroids

45
Q

Terpenes:

A

Isoprene units linked together

Smallest terpene= 2 isoprene units linked together=monoterpene

Names of common terpenes:
-farnescene
-squalene
-beta carotene

46
Q

Mixed terpenes:

A

Terpenes with non-terpene component attached :

-CoQ
-Vit K
-Farnesylated proteins

47
Q

Steroids:

A

Complex molecules made from 6 isoprene units

Made from cholesterol

48
Q

Cholesterol synthesis review:

A
49
Q

Most cholesterol synthesis occurs in the liver:

A

-Makes bile
-Make lipoproteins: LDL to cary cholesterol to tissues

LDL binds to a receptor on the cell and is internalized, broken down within the cell, and cholesterol is released.

50
Q

Familial hypercholesteremia:

A

inherited defect of LDL receptors:
leads to an increase in circulating LDL, and therefore cholesterol, in the blood

-Increases risk of myocardial infarction

51
Q

Cholesterol is a precursor to steroid hormones:

A

al animal steroids are derived from cholesterol.

Cholesterol is converted to pregnenolone, which is then converted to various other steroids hormones

52
Q

Plant sterols have a similar structure to cholesterol:

A

Used in plant membranes

can compete with intestinal cholesterol absorption.

(helps lower LDL cholesterol levels)

53
Q

Cardiac glycosides are derivatives of plant sterols:

A

Note the lipid attached to the carbohydrate: this is an isoprenoid ring structure.

Digoxin: used to treat heart failure and atrial fibrilation

BMS 100 Test 2 (16 decks)

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