Lipid Catabolism

Question 1

What does an increased fat intake without appropitate energy expenditure lead to?

Answer 1

Increased number of adipocytes

More fat in the adipocytes

Question 2

What is an adipocyte?

Answer 2

A fat cell

Question 3

What does control of energy balance depend on?

Answer 3

Genetic
- protein messengers, regulating appetitie

Environmental
- food abundance, fashionable foods

Question 4

What is fat needed for?

Answer 4

As an energy source (twice as much as carb and protein)

for essential fatty acids
- some polyunsaturated fatty acids cant be made in the body, so you need to take them in your diet

For fat soluble vitamins
- ADEK - absorption of these vitamins is closely linked to that of fat

Question 5

What might a deficiency in certain fatty acids result in?

Answer 5

Deficiencies can lead to membrane disorders, skin permeability and mitochondrial damage (reduction in energy production)

Question 6

What does the uptake of vitamins need?

Answer 6

Associated with the uptake of fat

Question 7

What are the different types of lipids?

Answer 7

Simple lipids (triglycerides, fatty acids)
Compound lipids (phosolipids, glycolipids, lipoprotein)
Steroids (cholesterol, steroid hormones)

Question 8

What make up lipids?

Answer 8

Hydrocarbons
- hydrogen and carbon

Usually contain long chain fatty acids
Insoluble in water

Question 9

What is the main energy form in adipose tissue?

Answer 9

Triglycerides

Question 10

Describe triglycerides?

Answer 10

Hydrophobic
Compact - why fat can provide so much energy
Made up from 3 fatty acids and glycerol

Question 11

What is the linkage between the glycerol and fatty acids?

Answer 11

ester link

Question 12

Are fatty acids straight or branches?

Answer 12

Straight usually

Question 13

What does saturated mean?

Answer 13

No double bonds

Question 14

What does unsaturated mean?

Answer 14

One double bond

Question 15

What does polyunsaturdated mean?

Answer 15

Several double bonds

Question 16

What is configuration do the double bonds in fatty acid?

Answer 16

Cis

Question 17

What is cis configuration?

Answer 17

R1 and R2 are horizontally opposite each other on the same plane

Question 18

What is trans configuration?

Answer 18

R1 and R2 are diagonally opposite each other in the double bond

Question 19

Can our body synthesis polyunsaturated fatty acids?

Answer 19

Not usually

Question 20

How are fatty acids named?

Answer 20

Carboxyl group is number 1 C1 and then the rest named after that

OR

Carbon that is adjacent to the carobxyl group is alpha, and then there is an omega carbon - greek way

Question 21

Describe the melting point of fatty acids. 8 carbons long, and longer?

Answer 21

8 Carbons or less - liquid at room temp

longer - are solid

Question 22

Do double bonds higher or lower the melting point?

Answer 22

Lower the melting point

Question 23

Describe the state of plant and animal fats?

Answer 23

Plant - liquid, contain unsaturated fatty acids

Animal - Solid, contain stearic acid and palmitic acid

Question 24

What are the main products of lipid digestion?

Answer 24

Glycerol
Fatty acids
monoglycerides

Question 25

Where is glycerol readily absorbed?

Answer 25

into epithelial cells of intestine

Question 26

Where are the products of lipid digestion absorbed into?

Answer 26

The mucosal cells of the intestine
short and medium chain - entry portal blood
Long chain and mono - resynthesized into triglycerides (chylomicrons)

Question 27

What is the chylomicron a good way for? (NOT GOOD)

Answer 27

a way of transporting dietary fats into the bloodstream

Question 28

What happens to the chylomicrons at uncle and adipose tissue?

Answer 28

They are attacked and cleaved by lipoprotein lipases

Question 29

What then happens to the free fatty acids broken up by the lipoprotein lipase?

Answer 29

They are resynthesized to triacylglycerols (in adipose tissue for storage)
Oxidised to provide energy

Question 30

What is lipolysis?

Answer 30

The breakdown of lipids

Question 31

What is fat stored as?

Answer 31

Adipose tissue

Question 32

What breaks down the stored fats?

Answer 32

Hormone sensitive lipase ( e.g adrenaline - sensitive) occurs when energy is needed

Question 33

What happens to the fatty acid if it needs to be used for energy?

Answer 33

It needs to be oxidised to generate energy
But before that it must be converted to CoA derivatives
Occurs in the cytoplasm
Requires 2 ATP

Question 34

Where does further oxidation of fatty acids take place?

Answer 34

Further oxidase of fatty acids occurs in the mitochondiral matrix

Thus there needs to be a transport mechanism to take into mitochondria

Question 35

What mechanism takes the fatty acid to be further oxidised in the mitochondrial matrix?

Answer 35

Carnitine shuttle

Question 36

How does the carnitine shuttle work?

Answer 36

In the cytoplasm the fatty acids are transferred from acyl-CoA to carnitine
Acyl-carnitine transporter in inner membrane - facilitates anti port of acyl carnitine into the mictrondriaon and carnitine out
Net result - acyl CoA located in mitochondrial matrix

Question 37

What is beta oxidation?

Answer 37

Cycle of reactions that happen in the mitochondrial matrix

Question 38

What is the product of each cycle of beta oxidation?

Answer 38

1 Acetly-CoA
1 Fatty acyl-CoA shortened by 2 carbon atoms
1 FADH2
1 NADH + H+

Question 39

How is glycerol broken down?

Answer 39

Activated to glycerol-3-phosphate by glycerol kinase

Question 40

Where are ketone bodies formed?

Answer 40

In liver mitochondria

Question 41

What can peripheral tissues do with ketone bodies?

Answer 41

Alternative way for the body to move energy around, they can covert back to acetyl-CoA which can enter the TCA cycle

Question 42

What happens to oxaloacete in starvation or uncontrolled diabetes?

Answer 42

It is consumed for gluconeogensis

Question 43

What can accumulation of ketone bodies in the blood do?

Answer 43

Can lead to severe acidiosis
Impairs tissue function, particularly CNS
Smell of acetone can be detected in breath