Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Lipids and Lipid Metabolism > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

what are steroids

A

one subclass of a broad range of lipids which includes cholesterol known as isprenoids or terpenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is cholesterol

A
  • is a major human sterol
  • present in the diet and synthesized, especially in the liver
  • membrane component
  • precursor to bile acids and steroid hormones
  • Vitamin D precursor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

true or false; cholesterol reduces the fluidity in the membrane stabilizing the extended chain of conformations of hydrocarbon tails of fatty acids due to hydrophobic interactions

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

where is cholesterol present

A

animal tissues in the diet; as free cholesterol and cholesterol esters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

true or false; diets high in animal fats can result into dangerously high levels of blood cholesterol

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what exacerbates high cholesterol levels in the blood

A

due to the presence of fatty acids in the diet eg. from butter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

true or false; unsaturated fatty acids eg olive oil, help lower blood cholesterol

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where is cholesterol synthesized in the human body

A

the liver and contributes to its concentration in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a circulatory form of cholesterol

A

LDLs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

true or false; high levels of cholesterol inhibits the synthesis of LDL receptor proteins

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is bad that high levels of cholesterol inhibit the synthesis of LDL receptor proteins

A

means that LDL levels in the blood tend to increase, in turn enhancing atherosclerosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

true or false; there is a strong correlation between high blood cholesterol and the incidence of atherosclerosis

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what happens during atherosclerosis

A

deposition of cholesterol, esters and other materials lead to the narrowing of the arteries and subsequent damage to arterial walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is a heart attach or myocardial infection due to

A

the blocking of coronary artery which part of the heart muscle is damaged by lack of oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where is cholesterol assembled from

A

acetyl CoA units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the key units to the biosynthesis of steroids and terpenes

A

isoprene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Stage 1 of isoprenoid synthesis

A
  1. ) condensation of 2 acetyl CoA
  2. ) condensation with another acetyl CoA
  3. ) formation of mevalonate is completed by the reduction of the thioester that gives primary alcohol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Stage 2 of isoprenoid syntehsis

A
  1. ) pyrophosphorylation of mevalonate (2 mol of ATP)
  2. ) ATP driven decarboxylation and B-elimination of phosphate ion gives IPP
  3. ) enzyme catalyzed isomeration —> DMAPP
  4. ) DMAPP coupled to 2X IPP —> H+ loss to give FPP
  5. ) joining together of two FPP by a two electron oxidation gives SQUALENE
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Stage 3 of isoprenoid sythesis

A

key enzyme oxidosqualene cyclase; forms the multiple ring structure squalene 2,3 epoxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the major regulatory enzyme in cholesterol biosynthesis

A

HMG-CoA reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

true or false; HMG-CoA reductase is hormonally controlled by insulin and glucagon

A

true

22
Q

true or false; the transcription and translation of the enzyme can be suppressed by the presence of cholesterol in cells

A

true

23
Q

true or false; HMG-CoA reductase is also a target for drugs such as statins that are taken to lower blood cholesterol by inhibiting endogenous synthesis

A

true

24
Q

true or false; cholesterol is the precursors for a number of steroid hormones including sex steroids and coricosteroids

A

true

25
Q

what are androgens

A

male sex hormones

  • synthesized in the testes
  • responsible for the development of male secondary sex characteristics
26
Q

what are estrogens

A

female sex hormones

  • synthesized in the ovaries
  • responsible for the development of the female secondary sex characteristics and control of the menstrual cycle
27
Q

true or false; cholesterol undergoes minor modifications to make bile acids which condense with the amino acids glycine and taurine to form bile salts

A

true

28
Q

What are the amino acids that cholesterol condenses with to form bile salts

A

glycine and taurine

29
Q

What are isprenoids

A

come from mevalonate structure

30
Q

Purpose of vit A

A

serves as the site of the primary photochemical reaction in vision

31
Q

purpose of vit D

A

regulates Ca and Phosphorous metabolism

32
Q

purpose of Vit E

A

serves an an antioxidant; necessary for reproduction in rats and may be necessary for the reproduction in humans

33
Q

purpose of Vit K

A

has regulatory function in blood clotting

34
Q

true or false Vit A only occurs in the animal world

A

true

35
Q

Describe Vit A structure

A
  • exclusively unsaturated hydrocarbon (B-carotene)
  • found in the plant world in the form of a provitamin in a group of pigments called carotene
  • enzyme catalyzed cleavage of B-carotene followed by reduction gives two molecules of vit A
36
Q

What is Vit D

A

involved in the regulation of Ca and P metabolism

- most abundant in the circulatory system

37
Q

true or false; if vit D is exposed to UV undergoes ring opening to create vit D3

A

true

38
Q

What is the “English Disease” and what can cure it

A
  • soft bones primarily in young children
  • very common in the industrial revolution in England
  • cured by sunlight or a good diet of cod liver oil
39
Q

What causes Rickets

A

Vit D deficiency

- impaired mineralization , a lack of Calcium phosphate

40
Q

Osteoporosis

A

lack of Vit D in the elderly

41
Q

What is cholecalciferol

A

Vit D3

42
Q

What is Vit D2

A

ergosterol

  • derived from plant sterols and is present in milk
  • inactive
43
Q

What does active Vit D stimulate

A

the synthesis of calcium binding protein, increases the absorption of dietary calcium and phosphate from the gut and also assists with deposition of these ions in the bone as calcium phosphate

44
Q

recommended does of Vit D

A

10 micorgrams, 250 micrograms is safe

45
Q

what is hypervitaminosis

A

higher levels of vit D

  • causes high plasma calcium
  • over calcification
  • hypertension
  • kidney stones
46
Q

What is Vit E

A

an antioxidant; traps HOO and ROO radicals formed as a result of oxidation of O2 of unsaturated chains in membrane phospholipids

47
Q

What is the most acitive form of vit E

A

a-tocopherol

48
Q

What is vitamin K

A

important role in blood clotting

- long hydrocarbon chain consists of repeating isoprene units

49
Q

true or false; the biosynthesis of cholesterol proceeds by condensation of 5C isoprenoid unit

A

true

50
Q

where are ispoprenoid units derived from

A

the reaction of 3 acetyl CoA units

Lipids and Lipid Metabolism (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions