Brainscape's Knowledge GenomeTM

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


See full index

Metabolism > Week 5 > Flashcards

Week 5 Flashcards

0
Q

What are the functional roles of apoproteins?

A

Recognition of cell surface receptors or activation of enzymes

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

Describe how the structure of a lipoprotein enables it to perform its function.

A

Hydrophobic regions that interact with lipids and hydrophilic regions that interact with water.

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

What are the two remnant classes of lipoproteins and what are they remnants of?

A

Chylomicron remnants - removal of TAGs from chylomicrons

IDLs - removal of lipids from VLDLs

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

What is the function of chylomicrons?

A

Transport of dietary lipids from gut to the tissues such as adipose tissue

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

What is the function of LDLs?

A

Transport of cholesterol from the liver to the tissues

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

What is the function of HDLs?

A

Transport of cholesterol from tissues to the liver for disposal as bile salts

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

What is the function of VLDLs?

A

Transport of TAGs from liver to adipose tissue for storage

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

Describe how fatty acids from the diet are transported to the tissues.

A

TAGs hydrolysed by pancreatic lipase, fatty acids absorbed into epithelial cells of the small intestine.
Reesterified to triacylglycerols with glycerol phosphate from glucose metabolism.
Packaged into chylomicrons with other dietary lipids (cholesterol, fat soluble vitamins). Transported to tissues via lymphatic system then blood stream.
Tissues have extracellular enzyme lipoprotein lipase - hydrolyse TAGs, take up fatty acids and convert to TAGs for storage.

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

What is the difference between a primary and secondary dyslipoproteinaemia?

A

Primary are inherited errors of metabolism, secondary are acquired secondary to diet, drugs, or an underlying condition like diabetes.

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

Why do you measure fasting plasma glucose when diagnosing hyperlipoproteinaemias?

A

Check for fasting

Check for diabetes

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

What is type 1 hyperlipoproteinaemia?

A

Defective lipoprotein lipase - chylomicrons in fasting plasma. No link with coronary artery disease.

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

What is type 2a hyperlipoproteinaemia?

A

Raised LDL due to defective LDL receptor. Associated with coronary artery disease.

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

What is type 2b hyperlipoproteinaemia?

A

High LDL and VLDL, associated with coronary artery disease. Defect unknown.

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

What is type 3 hyperlipoproteinaemia?

A

Raised IDL and chylomicron remnants due to defective Apoprotein E - associated with coronary artery disease.

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

What is type 4 hyperlipoproteinaemia?

A

Raised VLDL - defect unknown. Associated with coronary artery disease.

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

What is type 5 hyperlipoproteinaemia?

A

Raised fasting chylomicrons and VLDLs in fasting plasma - defect unknown. Associated with coronary artery disease.

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

How would you treat hyperlipoproteinaemia?

A

1) diet and lifestyle - reduce intake of cholesterol, and TAGs especially those containing saturated fatty acids.
2) statins inhibit HMG CoA reductase
3) bile salt sequestrants such as cholestyramine increase the rate of disposal of cholesterol by conversion into bile salts in the liver - they bind bile salts in the gut and prevent them being reabsorbed into the hepatic-portal circulation.

17
Q

What are the effects of statins?

A

Inhibit cholesterol synthesis by inhibiting activity of HMG CoA reductase.
Increase expression of lipoprotein lipase.

18
Q

What is lipoprotein lipase? Where is it found? What increases is expression?

A

Enzyme that catalyses hydrolysis of TAGs from chylomicrons and VLDLs - fatty acids taken up by tissues, glycerol transported to liver.
Found in capillaries in tissues such as adipose and muscle.
Insulin.

19
Q

What is LCAT?

A

Lecithin:cholesterol acyltransferase - restores the stability of lipoproteins by esterifying cholesterol from the surface, forming cholesterol esters that make up the core.
Uses fatty acids from lecithin (phophatidylcholine)

20
Q

What is the consequence of LCAT deficiency?

A

Unstable lipoproteins of abnormal structure and a failure of lipid transport - lipids are deposited in many tissues, leads to atherosclerosis.

21
Q

Why do cells prefer to take up cholesterol from plasma lipoproteins?

A

Allows whole body cholesterol content to be closely controlled.

22
Q

Which cells can’t synthesise cholesterol from Acetyl CoA?

A

Erythrocytes

23
Q

How do cells take up cholesterol?

A

Cells requiring cholesterol synthesise and express LDL receptors.
These recognise and bind Apo B100.
This is taken into the cell by receptor mediated endocytosis.
It is then subjected to lysosomal digestion - cholesterol esters are then converted to cholesterols, which are either stored as cholesterol esters, or used.

24
Q

What prevents cholesterol accumulating in the cell?

A

Cholesterol inhibits the synthesis of cholesterol within a cell. It also inhibits the synthesis and expression of LDL receptors.

25
Q

What is the difference between being homozygous and heterozygous for type 2a hyperlipoproteinaemia?

A 
Homozygous = complete absence of LDL receptors, develop atherosclerosis early in life.
Heterozygous = deficiency of LDL receptors, develop atherosclerosis later in life.
26
Q

How many electrons do not reach the end of the electron transport chain?

A

Between 0.1-2%

27
Q

What is the fate of electrons that do not reach the end of the electron transport chain?

A

Prematurely reduce oxygen to form superoxide radicals (O2-)

28
Q

What are superoxide radicals also known as?

A

Free radicals or reactive oxygen species.

29
Q

How are superoxide radicals dealt with in humans?

A

converted to hydrogen peroxide by superoxide dismutase (SOD)

Broken down to oxygen and water by catalase

30
Q

What happens if there is excess superoxide radicals that are not converted to hydrogen peroxide?

A

Oxidise proteins, lipids and DNA.

Lipid peroxidation can damage membranes.

31
Q

What other radical can damage cells, especially cell membranes?

A

Hydroxyl radicals.

32
Q

How else are radicals produced?

A

Ionising radiation
Herbicides such as paraquat
Superoxide radicals react with nitric oxide to produce peroxynitrite (ONOO-)
Drugs such as antimalarials.

33
Q

What is glutathione?

A

Tripeptide (glutamate-cysteine-glycine)

34
Q

How is glutathione involved in neutralisation of ROS?

A

Naturally abundant in cells, can donate its hydrogen from its SH group and reduce ROS, forms glutathione disulphide.

35
Q

How is glutathione disulphide converted back to glutathione in cells?

A

Regenerated by NADPH

36
Q

What is oxidative stress?

A

Low levels of antioxidants - underlies a range of conditions including atherosclerosis, Parkinson’s and Alzheimer’s.

37
Q

What is the role of oxidative stress in inflammation?

A

iNOS (inducible nitrogen oxide synthesis) synthesises large amounts of nitric oxide which is converted into peroxynitrite radicals.

38
Q

What is an oxidative burst?

A

Release of ROS in a monocyte and neutrophil destroys cell and surrounding fungal or bacterial cells.
Produced by membrane bound multienzyme complex NADPH oxidase.

39
Q

How does NADPH oxidase work?

A

Present in cell membrane and membranes of phagosomes, transfers electrons from NADPH across the membrane to oxygen - makes superoxide radicals.
Important in atherosclerosis.

Metabolism (9 decks)

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