Brainscape's Knowledge GenomeTM

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


See full index

Biochem II 322 > Lecture 14 > Flashcards

Lecture 14 Flashcards

1
Q

What are the main precursors of cholesterol synthesis?

A

acetyl-CoA, acetate, mevalonate (committed step), DMAPP and IPP

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

Where does cholesterol synthesis occur?

A

Cytosol

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

Which enzyme is found in cholesterol synthesis but not ketogenesis?

A

HMG-CoA reductase

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

What is step 1 in cholesterol synthesis? What’s this reaction called?

A

React DMAPP and IPP to form geranyl pyrophosphate (10-C). This reaction is called “head-to-tail condensation”

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

What is step 2 in cholesterol synthesis (Starting from DMAP and IPP)?

A

Geranyl pyrophosphate combines with isopentyl pyrophosphate to form farnesyl pyrophosphate.

Big picture: combine two pyrophosphates to make an even bigger pyrophosphate

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

What is step 3 in cholesterol synthesis?

A

Reduce farnesyl pyrophosphate with NADPH + (H+) to form squalene

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

What is step 4 in cholesterol synthesis?

A

Add oxygen, reduce squalene with NADPH to form squalene 2,3 epoxide + water and NADP+

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

What is step 5 in cholesterol synthesis?

A

Form lanasterol

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

What is the last step in cholesterol synthesis?

A

Multistep process from lanasterol to cholesterol

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

What is step 1 in the exogenous pathway of cholesterol transport?

A

Cholesterol moves directly into intestinal mucosal cells to be packaged into chylomicrons

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

What is step 2 in the exogenous pathway of cholesterol transport?

A

Chylomicrons travel through blood vessels. Body cells recognize apolipoproteins if they need fat (i.e., adipose ,muscle, adrenal gland, gonads…etc)

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

What is step 3 in the exogenous pathway of cholesterol transport?

A

Chylomicron remnants (what’s left after delivery to the body tissues) go to the liver

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

What is step 1 in the endogenous pathway of cholesterol transport?

A

Cholesterol is converted to cholesteryl esters (CE) in the liver.

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

What are cholesteryl esters and why are they useful?

A

They’re cholesterol but with long hydrocarbon tails, which is useful for packing in transport

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

What is step 2 in the endogenous pathway of cholesterol transport?

A

Cholesteryl esters are packaged into VLDLs

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

What is step 3 in the endogenous pathway of cholesterol transport?

A

VLDLs go from the liver to the tissues in the blood

17
Q

What is step 4 in the endogenous pathway of cholesterol transport?

A

Lipases remove FAs from VLDLs, which convert them to LDLs

18
Q

What is step 5 in the endogenous pathway of cholesterol transport?

A

Unused LDLs return to the liver via LDL receptors

19
Q

What happens to a person with mutant LDL receptors?

A

They suffer from high cholesterol levels since the LDLs can’t enter the liver to be excreted or used

20
Q

Describe the process of artery occlusion due to high cholesterol levels

A

Monocytes are attracted to oxidized lipoproteins that have stuck to the extracellular matrix. They differentiate into macrophages, which cannot control how much cholesterol they take up. Eventually, they take up so much fat that they form foam cells, which eventually commit apoptosis. Plaques form from dead foam cells, cholesterol, lipoprotein, and lipid buildup

21
Q

What are polyketides?

A

They are specialized lipids typically found in bacteria. They form antibiotics.

22
Q

What are terpenes?

A

They are specialized lipids typically found in plants and give them aroma

23
Q

What are the precursors of polyketides and terpenes?

A

acetate, acetyl-CoA, IPP, and DMAPP

24
Q

What is the monomer in polyketides?

A

Malonyl-CoA

25
Q

How many types of polyketide synthases are there?

A

3

26
Q

Describe Type I polyketide synthases

A

There’s a single protein with many modules. Each active site is only used once. Product is predictable.

27
Q

Describe Type II polyketide synthases

A

There are multiple proteins that can be used once or many times. Product cannot be predicted

28
Q

Which enzymes are needed to add a malonyl-CoA unit every time?

A

Ketone synthase (KS) and transacyltransferase (AT)

29
Q

What does ketoreductase (KR) do? What happens if it’s not present?

A

It reduces carbonyls to alcohols. Without it, you’re left with a carbonyl

30
Q

What does dehydratase (DH) do? What happens if it’s not present?

A

It oxidizes alcohols to carbon-carbon double bonds. Without it, you’re left with an alcohol

31
Q

What does enoyl-reductase (ER) do?

A

It reduces carbon-carbon double bonds to hydrocarbons. Without it, you’re left with a carbon-carbon double bond

32
Q

How many carbons are in a terpene? Diterpene?

A

10

20

Biochem II 322 (20 decks)

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