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Biochem > Chapter 29 > Flashcards

Chapter 29 Flashcards

1
Q

what are triacylglycerols?

A

storage form of fatty acids

reservoir of potential energy

primary fuel storage in humans

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2
Q

what are membrane lipids?

A

phospholipids and sphingolipids

inner converting membrane compartments

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3
Q

What is Cholesterol?

A

membrane component and precursor to steroid hormones

increases/controls membrane fluidity

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4
Q

what is the central portion of triacylglycerol metabolism?

A

liver

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5
Q

what happens to triacyclglycerols after they become free fatty acids?

A

they are released into the bloodstream and head to the liver

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6
Q

what are the two fates of triacylglycerol?

A

glycerol

free fatty acids

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7
Q

How is Triacylglycerol synthesized?

A

Triacylglycerol synthase is bound to the endoplasmic reticulum, synthesizes triacylglycerol from phosphatide and acyl CoA

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8
Q

how are cholesterol and triacylglycerols transported into the blood?

A

in the form of lipoprotein particles

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9
Q

what do lipoprotein particles consist of?

A

they consist of a protein(s) component and various lipids, depending on the type of particle

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10
Q

what do the protein(s) of lipoprotein particles do?

A

they serve to solubilize the lipids and to direct the particles to specific targets

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11
Q

how are lipoprotein particles classified?

A

according to density

the greater the proportion of lipid, the less dense the particle

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12
Q

what is Low-density lipoprotein (LDL)?

A

the major carrier of cholesterol in the blood

bad cholesterol

distributes through body

causes plaque build up

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13
Q

what is high-density lipoprotein (HDL)?

A

carries cholesterol released into the blood back to the liver (reverse cholesterol transport)

good cholesterol

scavenge cholesterol from body for liver

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14
Q

what do Apo-lipoproteins do?

A

target the lipoprotein particles to different organs

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15
Q

what cells have LDL/HDL receptors?

A

receptor-mediated endocytosis cells

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16
Q

why is the liver so important to lipid synthesis?

A

it is the central portion of the triacylglycerol metabolism

it is the center part for leaving and receiving of cholesterol

major site of cholesterol biosynthesis

17
Q

what is the process of cholesterol formation from receptor-mediated endocytosis?

A

LDL binds to LDL receptor on a cell

it is internalized

Lysosomal Hydrolysis separates amino acids and cholesteryl oleate

cholesterol is formed

18
Q

why is cholesterol vital to the body?

A

it maintains proper fluidity of animal cell membranes and is the precursor of steroid hormones such as progesterone, testosterone, estradiol, and cortisol

19
Q

how is cholesterol synthesis regulated?

A

by controlling the amount and activity of HMG CoA reductase

20
Q

what is HMG CoA reductase?

A

the enzyme that catalyzes the synthesis of mevalonate

regulated allosterically

21
Q

what is the committed step of cholesterol synthesis?

A

Actyl CoA + acetoacetyl CoA

22
Q

when is HMG CoA reductase active?

A

during dephosphorylation

23
Q

how is HMG CoA Reductase regulated?

A

Gene expression - rate of mRNA synthesis

Rate of translation of the mRNA
degradation of the HMG CoA Reductase protein (control destruction of HMG)

Phosphorylation of HMG CoA Reductase decreases activity (controls phosphorylation of HMG)

24
Q

what can cholesterol become?

A

Glucocorticoids

Mineralocorticoids

Androgens → Estrogens

25
Q

how is vitamin D derived from cholesterol?

A

cholesterol is catalyzed by the energy of sunlight

26
Q

why is vitamin D important?

A

it plays a key role in the regulation of calcium and phosphate metabolism

27
Q

what is the active form of vitamin D?

A

calcitriol

28
Q

how is calcitriol formed?

A

from cholesterol in a pathway that involves ultraviolet light-induced cleavage of one of the rings of the steroid nucleus

29
Q

what is rickets?

A

deficiency of vitamin D that results in inadequate calcification of cartilage and bone

30
Q

what can vitamin D deficiency cause?

A

rickets

osteomalacia

31
Q

what is osteomalacia?

A

a condition characterized by soft weak bones

Biochem (12 decks)

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