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BIOCHEM FINALS > CHOLESTEROL, LIPOPROTEIN, AND STEROID METABOLISM > Flashcards

CHOLESTEROL, LIPOPROTEIN, AND STEROID METABOLISM Flashcards

1
Q

is a fatty substance found in animal tissues.

Importance:
building cell membranes
producing hormones making vitamin D

A

Cholesterol

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2
Q

Cholesterol Sources

A

food

Liver (central role in regulates cholesterol levels in the body)

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3
Q

is a fluid that helps digest food.
made in the liver and stored in the gallbladder

A

bile

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4
Q

Contents: cholesterol, bile salts, and other substances.

A

bile

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5
Q

are particles that carry cholesterol and other fats in the blood.

A

Plasma lipoproteins

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6
Q

3 main types of lipoproteins:

A

HDL, LDL, VLDL

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7
Q

called “good” cholesterol because it helps to remove cholesterol from the blood and take it back to the liver.

A

HDL (high-density lipoprotein)-

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8
Q

called “bad” cholesterol because it can build up in the arteries and increase the risk of heart disease.

A

LDL (low-density lipoprotein)

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9
Q

carries triglycerides, a type of fat.

A

VLDL (very low-density lipoprotein)

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10
Q

is a condition in which plaque builds up in the arteries.

A

Atherosclerosis:

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11
Q

Cholesterol can enter the liver from three main sources:

A

dietary cholesterol

cholesterol synthesized in other tissues (extrahepatic synthesis)

cholesterol synthesized in the liver itself (hepatic synthesis)

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12
Q

cholesterol synthesized in other tissues

A

(extrahepatic synthesis

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13
Q

cholesterol synthesized in the liver itself

A

(hepatic synthesis)

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14
Q

are a type of lipid molecule with a characteristic four-ring structure called the steroid nucleus. They are found in all eukaryotic cells.

A

Sterols

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15
Q

[is the most abundant sterol in animal tissues. It is essential for the synthesis of bile acids, which are necessary for fat digestion.

A

Cholesterol

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16
Q

formed when a fatty acid is attached to the hydroxyl group of cholesterol. This makes the molecule even more hydrophobic than free cholesterol. not found in membranes and are normally present only in low levels in most cells

A

Cholesteryl esters

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17
Q

is the major control point for cholesterol biosynthesis.

A

HMG CoA reductase

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18
Q

*(When cholesterol levels in the cell are ___, a protein called SREBP-2 (sterol regulatory element-binding protein-2 ) is released from the endoplasmic reticulum (ER) and travels to the nucleus, where it turns on the gene for HMG-CoA reductase. (INCREASED CHOLESTEROL SYNTHESIS)

A

low

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19
Q

When cholesterol levels are __, SREBP-2 is kept in the ER and cannot turn on the gene for HMG-CoA reductase. (DECREASED CHOLESTEROL SYNTHESIS)

A

high

20
Q

When cholesterol levels are __, the enzyme is marked for destruction (DECREASED CHOLESTEROL SYNTHESIS)

A

high

21
Q

When HMG-CoA reductase is __, it is inactive. This means that it cannot make cholesterol.

A

phosphorylated

22
Q

increase cholesterol synthesis

A

Insulin and thyroxine

23
Q

__ decrease cholesterol synthesis.

A

Glucagon and glucocorticoids

24
Q

The ___ are a type of medication that LOWERS CHOLESTEROL LEVELS in the blood.

A

statin drugs

25
Q

is a mixture of water, organic molecules, and inorganic molecules.

A

Bile

26
Q

The main organic molecules in bile are ___

A

lecithin and conjugated bile salts.

27
Q

-have 24 carbon atoms, two or three hydroxyl groups, and a side chain with a carboxyl group

A

Bile acids

28
Q

is caused by the precipitation of cholesterol in the gallbladder. This can be caused by a decrease in bile acids or an increase in cholesterol secretion.

A

Cholelithiasis, or gallstone disease

29
Q

are macromolecular complexes that transport lipids in the blood.
Composed of a core of lipids (triglycerides and cholesteryl esters) surrounded by a shell of amphipathic phospholipids, free cholesterol, and apolipoproteins

A

Lipoproteins

30
Q

The lipids carried by lipoproteins can come from two sources:

A

diet (exogenous) or
synthesis in the body (endogenous).

31
Q

The cholesterol content of plasma lipoproteins is measured in a __

A

fasting blood test.

32
Q

are the largest and least dense particles, containing the highest percentage of triglycerides and the lowest percentage of protein.

A

Chylomicrons

33
Q

are successively denser, with higher ratios of protein to lipid.

A

VLDL and LDL

34
Q

__ particles are the smallest and densest.

A

HDL

35
Q

are proteins that are associated with lipoprotein particles.

Functions:
Providing recognition sites for cell-surface receptors
Activating or co-enzyming enzymes involved in lipoprotein metabolism
Providing structural support for the lipoprotein particles

A

Apolipoproteins

36
Q

is a protein that is unique to chylomicrons. It is made in the rough ER and Golgi apparatus.

A

Apo B-48

37
Q

__ helps to load apo B-48 with lipids.

A

Microsomal triglyceride transfer protein (MTP)

38
Q

is an enzyme that breaks down triglycerides in chylomicrons.

A

Lipoprotein lipase (LPL)

39
Q

As VLDLs lose triglycerides, they become smaller and denser and are called __.

A

IDLs

40
Q

are the main carriers of cholesterol in the blood

A

LDLs

41
Q

Secretion is controlled by the hypothalamus and pituitary gland, helps the body respond to stress.

A

cortisol

42
Q

Secretion is controlled by the kidneys and angiotensin II. helps the body regulate blood pressure.

A

Aldosterone

43
Q

Secretion is controlled by the pituitary gland. are converted to testosterone and estrogens in other tissues.

A

Androgens

44
Q

Secrete testosterone in response to LH (luteinizing hormone).

A

testes

45
Q

is important for male sexual development and function.

A

Testosterone

46
Q

Secrete estrogens and progesterone in response to LH and FSH (follicle-stimulating hormone).

A

ovaries

47
Q

__ are important for female sexual development and function

A

Estrogens and progesterone

BIOCHEM FINALS (6 decks)

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