Overview of Lipid Biochemistry Flashcards Preview

Digestive, Endocrine, and Metabolic Systems > Overview of Lipid Biochemistry > Flashcards

Flashcards in Overview of Lipid Biochemistry Deck (24):
1

Fatty acids are categorized as either ____________.

saturated or unsaturated

2

What is triglycerol?

A three-carbon chain with hydroxyl groups on each carbon.

3

Explain how fatty acids are a part of triglycerides – which can be put into gluconeogenesis – but cannot serve as substrates for gluconeogenesis.

The triglyceride carbons that go into gluconeogenesis come from the triacylglycerol backbone, not the fatty acid chains that get esterified to triacylglycerol to form triglycerides.

4

Describe the overall structure of phospholipids.

Phospholipids are based on the structure of triglycerides: there are two hydrocarbon chains esterified to a glycerol backbone, but the third carbon is replaced by a phosphate group.

5

Which kinds of lipids are the most polar? The least?

(Most polar)
Free fatty acids

(Least polar)
Triglycerides and cholesterol esters

6

What phospholipid ratio is tested for evaluation of fetal lung disease?

Phosphatidylcholine (a type of lecithin) : sphingomyelin ratio greater than 2 indicates lung maturity

7

Describe the synthesis of fatty acids and note the regulated step.

Acetyl co-a
(Acetyl co-a carboxylase) ***REGULATED STEP***
Malonyl co-a
(Fatty acid synthase – two-carbon transfers of acetyl co-a on to malonyl co-a and the subsequent growing fatty acid)
Fatty acids

8

Lipoprotein lipase does what ____________.

moves triglycerides from the blood to the adipose tissue

9

VLDL serves what purpose?

It delivers fat from the liver to adipose tissue.

10

Acetyl co-a carboxylase is stimulated by ___________.

glucose

11

Triglycerides are moved out of adipocytes by ______________.

hormone-sensitive lipase

12

When fatty acids move into liver or muscle cells, they bond with ____________.

acyl, for fatty acyl co-a

13

What is the regulated step in lipolysis?

Carnitine palmitoyl transferase (which pumps acyl into mitochondria)

14

True or false: free fatty acids are complexed to proteins in transport.

True.

15

Ketones are made from ____________ by the enzyme _______________.

acetyl co-a; HMG co-a synthase

16

Trace the cholesterol-synthesis pathway and list the regulated steps.

Acetyl co-a
(HMG co-a synthase)
HMG co-a (hydroxymethyl glutaryl co-a)
(HMG co-a reductase) ***REGULATED STEP; USES NADPH***
Mevalonate
Cholesterol

17

What are the five major groups of lipids?

Glycolipids
Phospholipids
Cholesterol
Triacylglycerides
Free fatty acids

18

VLDL is ________________.

triglycerides packed with proteins circulating in the blood

19

When glucagon is high and insulin low, triglycerides in adipose tissue are broken down by ______________.

hormone-sensitive lipase

20

Lipase breaks down triglycerides to triacylglycerol and free fatty acids that ______________. After getting there, what happens?

circulate to the liver; they must be converted to acetyl carnitines that get pumped into the mitochondria of hepatocytes by carnitine palmitoyl transferase 1 (which is the rate-limiting step in fat oxidation)

21

In the mitochondria of hepatocytes, fatty acids get _______________.

broken down in two-carbon fragments (beta oxidation) that enter the TCA cycle as acetyl co-a

22

The rate-limiting step in ketogenesis is _____________.

synthesis of Hmg Co-a

23

Sphingolipids have a ____________ backbone.

ceramide (nitrogen-containing because it is derived from serine)

24

HDL is thought to ________________.

deliver peripheral cholesterol to the liver

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