Brainscape's Knowledge GenomeTM

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


See full index

POM > cell metabolism 2 > Flashcards

cell metabolism 2 Flashcards

1
Q

What are the 5 classes of lipids?

A

Free fatty acids

Triglycerides

Phospholipids

Glycolipids

Steroids

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

Where are fatty acids stored?

A

Cytoplasm

Often as triglycerides

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

What are triglycerides?

A

Molecules made up of 3 fatty acids attached to a glycerol molecule

Attached via ester linkages

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

What do ester linkages do?

A

Help neutralise carboxylic acid groups

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

What are fats broken down into?

A

Fatty acids and glycerol

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

What is Acetyl CoA produced from?

A

Both types of major food molecules within mitochondria (fats and sugars + polysaccharides).

Mitochondria is where most of cellular oxidation reactions occur and where majority of cellular ATP is made

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

Where is fat derived from?

A

Diet

De novo biosynthesis (liver)

Storage deposits in adipose

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

Where are bile salts made and stored?

A

Made in liver

Stored in gall bladder

During digestion they pass from bile duct into intestine

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

Whats the role of bile salts?

A

Emulsify fats in intestine aiding their digestion and absorption

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

What are the fat soluble vitamins?

A

A, D, E, K

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

What does a lack of bile salts lead to?

A

Undigested and unabsorbed fats and steatorrhea (fatty stool)

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

What is Olistat?

A

Tetrahydrolipstatin

A potent inhibitor of gastric and pancreatic lipases

Chemically synthesised derivative of lipostatin (a product of streptomycin toxytrini)

Orlistat reduces fat absorption by 30% which is almost complexity excreted in faeces

Trials show it can treat obesity for up to 2 years

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

What are the main side effects of olistat?

A

Abdominal pain, urgency to defecate, increased flatus, steatorrhea

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

Where are lipids transferred to and how?

A

Transferred to the plasma by lipoproteins

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

What are the 5 types of lipoproteins and what are their sources?

A
  • Chylomicrons (CM): intestines
  • Very low density lipoproteins (VLDL): liver
  • Intermediate density lipoproteins (IDL): VLDL
  • Low density lipoproteins (LDL): IDL
  • High density lipoproteins (HDL): Liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What the role of the different lipoproteins?

A

CM: Dietary fat transporters

VLDL: Endogenous fat transport

IDL: LDL precursor

LDL: Cholesterol transport

HDL: Reverse cholesterol transport

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

How are chylomicrons made?

A

Digested dietary products are absorbed by enterocytes that line the brush border of small intestine

Triglycerides are resynthesised and are incorporated into chylomicrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How are chylomicrons transported?

A

Transported via lymphatics and into bloodstream

They acquired apoproteins from HDL following release into bloodstream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do chylomicrons enter the bloodstream?

A

They travel from lacteals of intestine to the thoracic duct to the left subclavian vein where they enter blood stream

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

Where is lipoprotein lipase located?

A

Capillary endothelial cells lining variety of tissues including adipose, heart and skeletal muscle

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

What reaction do fatty acids undergo?

A

B oxidation

Glycerol is returned to liver to be used in gluconeogenesis

22
Q

What is the role of apoprotein?

A

Chylomicrons pick up apoproteins from HDL

These can be recognised by lipoprotein lipases on the surface of adipose and skeletal muscle

23
Q

What do lipoprotein lipases do?

A

Breakdown triglycerides into fatty acids and glycerol Chylomicron remnants can pick up more apoproteins from HDL- allows them to be recognised by the liver

24
Q

What is so important about lipoproteins?

A

Transport hydrophobic molecules in an aqueous environment

25
Q

How is a lipoprotein structured?

A

Has a monolayer containing cholesterol and apoproteins

This surrounds a core of cholesterol esters and triglycerides

26
Q

What are cholesterol esters?

A

Synthesised in plasma from cholesterol and acyl chain of phosphatidylcholine (lecithin) via a reaction catalysed by lecithin:cholesterol acyltransferase (LCAT)

27
Q

What happens when apoprotein transfers onto HDL?

A

Formation of intermediate density lipoprotein

28
Q

How is LDL formed?

A

HDL can transfer cholesterol esters to IDL to make LDL

29
Q

What are LDLs taken up by?

A

Tissues with receptors for it

Macrophages

Liver

30
Q

What are HDLs?

A

Often called ‘good cholesterol’

Take cholesterol from peripheral tissues back to liver for use or disposal

Help lower total cholesterol

31
Q

What are LDLs?

A

Often called ‘bad cholesterols’

Prolonged elevation of LDL levels leads to atherosclerosis L

DLs transport cholesterol from liver to peripheral tissues (more than 40% of their weight is cholesterol esters)

32
Q

Whats the importance of fatty acid metabolism?

A

More than half of the body’s energy comes from fatty acid oxidation

This process is known as beta oxidation and results on formation of acetyl CoA

33
Q

What happens in the beta oxidation of fatty acids?

A

Fatty acid + ATP + HS-CoA (coenzyme A) -> Acetyl CoA + AMP + PPi Enzyme: Acetyl CoA synthase

34
Q

What is the carnitine shuttle?

A

Generation of acyl CoA species occurs in outer mitochondrial membrane

To transport the species into the matrix its coupled to the molecule carnitine to from acyl carnitine. acyl carnitine and carnitine are moved to and from the matrix by translocase

35
Q

What is primary carnitine deficiency?

A

Autosomal recessive Symptoms occur during infancy or early childhood

Symptoms include encephalopathies (cardiomyopathies, muscle weakness and hypoglycaemia)

Mutation in SLC22A5 which encodes a carnitine transporter results in reduced ability of cells to take up carnitine needed for beta oxidation of fatty acids

36
Q

What happens to acyl CoA in the beta oxidation cycle?

A

Undergoes oxidation, hydration, oxidation and thiolysis reactions

This results in production of 1 molecule of acetyl CoA and an acyl CoA species which is 2 carbons shorter than original (fatty acyl CoA)

37
Q

What occurs during the cycles of beta oxidation?

A

2 carbon units are consecutively removed from acyl CoA making acetyl CoA

On the final cycle, 2 acetyl CoA molecules are made In 7 cycles, 8 molecules of acetyl CoA are made

This acetyl CoA is made from a 16 carbon palmitoyl CoA molecule (B-oxidation of palmitoyl CoA)

38
Q

How are ketone bodies made?

A

Acetyl CoA made from beta oxidation enters TCA cycle only if B-oxidation and carbohydrate metabolism are balanced since oxaloacetate is needed for entry

When fat breakdown predominates, acetyl CoA forms acetoacetate, D-3-hydroxybutyrate and acetone. This is collectively known as ketone bodies

39
Q

What enzymes does fatty acid biosynthesis include?

A

Acetyl CoA carboxylase

Fatty acid synthase

40
Q

How are fatty acids formed?

A

Formed by decarboxylative condensation reactions involving acetyl- CoA and malonyl CoA

After each round of elongation, the fatty acid undergoes reduction and dehydration by action of ketoreductase, dehydratase and enol reductase activity

Growing fatty acid is linked to acetyl carrier protein (ACP)

41
Q

What does fatty acid synthesis involve? (carrier, reducing power, location)

A

Carrier: ACP

Reducing power: NADPH

Location: cytoplasm

42
Q

What does fatty acid degradation involve? (carrier, reducing power, location)

A

Carrier: CoA

Reducing power: FAD/NAD+

Location: mitochondrial matrix

43
Q

What is the overall reaction for lipogenesis?

A
44
Q

What happens when a fatty acid longer than 16 carbons is made?

A

Elongation of acyl group to make fatty acids longer than 16 carbons occurs seperately from palmitate syntheisis in the mitochondria and ER

45
Q

What does desaturation of fatty acids require?

A

Fatty acyl- CoA desaturases

46
Q

What enzyme makes oleic acid and palmitoleic acid from stearate and palmitate and what does it do?

A

delta- 9 desaturase

Generates a double bond nine carbons from the terminal carboxyl group

47
Q

Where does de novo FA biosynthesis occur in adults?

A

Liver, adipose tissue and lactating breast

48
Q

How does de novo biosynthesis differ in cancer?

A

Can happen in cancer cells where it shouldn’t

49
Q

Can we target FA synthetase in cancer?

A

Inhibition of FASN by cerulenin (antifungal antibiotic) can reduce tumour growth of ovarian cancer cells

50
Q

What catalyses the initial step in each cycle of fatty acid B-oxidation?

A

A family of different acyl- CoA- dehydrogenases

Each one can bind too fatty acid chain of varying length:

51
Q

What is medium chain acyl-coenzyme A dehydrogenase deficiency (MCADD)?

A

Autosomal recessive

Can be fatal if undiagnosed

If diagnosed pateints should never go without food for longer than 10-12 hours- should have a high carbon diet

Patints suffering illness or appetite loss or sever vomiting may need i.v. glucose

POM (48 decks)

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