W5 Fat Metabolism

Question 1

What are fats?

Answer 1

• Long chains of carbons (various lengths)

Question 2

How do fats get stored?

Answer 2

• Fats are stored as Triglycerides (TAG)

Question 3

Looking at the molecular structure of a fat how can you tell if it’s saturated or not?

Answer 3

• By the number of double bonds

Question 4

What are triglycerides carried around the body by?

Answer 4

• Lipoproteins

Question 5

What are lipoproteins?

Answer 5

• They are mini organelles that carry fats around the body

- They have water loving (hydrophilic) outside and water hating (hydrophobic) inside

Question 6

Name the four different types of lipoproteins

Answer 6

1. Chylomicron (ULDL) - Carries TAG
2. VLDL - Carries TAG
3. LDL - Carries Cholesterol Esterase
4. HDL- Carries Cholesterol Esterase

Question 7

What is the process of storing fats?

Answer 7

1. Chylomicron travels through the blood and docks onto LPL (on the vessel walls)
2. LPL then breaks the TAG down
3. Now left over is a chylomicron remnant
4. The liver breaks down and resynthesises chylomicrons

Question 8

Catabolic state:

- When you have no chylomicron the liver produces what to supply the muscles with TAG?

Answer 8

• VLDL

Question 9

• What does the lipolysis (breakdown of fats via hydrolysis) of TAG form?

Answer 9

• Lipolysis of TAG forms free fatty acids

Question 10

What is the lipolysis enzyme used for fat regulation:

Answer 10

• HSL (Hormone sensitive lipase) = only one with fat

- Lipase = enzyme hydrolysis’s TAG (FA & glycerol)

Question 11

• What is HSL activated by?

- Why do we want to activate HSL?

Answer 11

• Protein kinase

- Because in catabolic situations e.g. exercise

Question 12

• What is HSL unactivated by?

- Why do we want to unactivated HSL?

Answer 12

• Phosphatase

- Because we use HSL to store fats & It’ll happen when it’s getting a stimulus to store

Question 13

• What is Re-esterification?
• When exercising you need fatty acids out of your muscle cells. Is it harder to do this will lipolysis or Re-esterification?

Answer 13

• Putting fatty acids & glycerol back together to form triglycerides
• Re-esterification

Question 14

Give three different things that help carrier proteins can get transported across a cells membrane:

Answer 14

1. Fatty acid translocate (FAT/CD36)
2. Fatty acid binding protein (FABP)
3. Fatty acid transport protein (FATP)

Question 15

What is interstitial fluid?

Answer 15

• It’s between circulation and plasma membrane of muscle cell (sarcoplasm)

Question 16

Describe the 4 processes in which fats go from the blood stream into the muscle cell:

Answer 16

1. Fatty acids arrive at the Chylomicrons or VLDL
2. LPL is situated on endothelial cell of capillary
3. Fatty acids are transported into the cell (down concentration gradient)
4. This whole thing is a site of regulation

Question 17

• What is the Carnitine Shuttle?

Answer 17

• Getting fats into the mitochondria or how to move Acyl-coA from sarcoplasm –> mitochondria

Question 18

How many membranes do mitochondria have and what are they called?

Answer 18

• Two membranes:
  Outer - permeable to liquids
  Inner - impermeable to liquids

Question 19

What’s the 4 step process on how we get Acetyl-coA/fats into the mitochondria (Carnitine Shuttle)?

Answer 19

1. Carnitine palmitoyl transferase 1 (CPT1) sits on the outer layer of the membrane
2. Carnitine attaches to acetyl & coA is removed creating acylcarnitine. Which can then go through the inner membrane with the help of: Carnitine Acetyl Carnitine Translocase (CACT)
3. CACT helps Acetyl cross the inner membrane
4. CPT2 removes the carnitine and reattaches the coA

Now Acyl-coA is inside the mitochondria

Question 20

Beta(B)-Oxidation:
After the Carnitine Shuttle the left over acetyl-coA goes through the TCA cycle.
- What enzyme is the rate limiting enzyme in beta-oxidation?
- How many Acetyl-coA’s do you get after putting 16 through the TCA cycle?

Answer 20

• Beta Hydroxy Acyl-CoA dehydrogenase (B-HAD) is the rate limiting enzyme.
• 16 Acetyl-coA’s enter the TCA cycle and go round 7 times to produce 8 new acetyl-coA’s

Question 21

At what point does fat contribute to energy production?

1. When your glycogen levels are full.
2. When your glycogen levels are Half full.
3. When your glycogen levels are depleted.

Answer 21

3. When your glycogen levels are depleted.

Question 22

The concentration of plasma fatty acids will change during prolonged exercise.
Please describe what this change looks like.

Answer 22

• Initially there is a drop in plasma fatty acids

- Then a steady increase in plasma fatty acids

Question 23

Give me two hormone that help increase lipolysis and get fatty acids into the blood stream. Also do they increase or decrease?

Answer 23

• Insulin reduction

- Adrenaline increase

Question 24

Does plasma fatty acid availability increase fatty acid oxidation?
If so why?

Answer 24

• Yes, it does increase fatty acid oxidation
• Because increasing fatty acids results in greater flux therefore, giving the muscle the opportunity to take in the fat which results in more fat oxidation

Question 25

• When LDL is greater than HDL is this good?

Answer 25

No it is a bad thing

Question 26

What is Atherosclerosis?

Answer 26

• A disease in your arteries because of fatty material being left on the inner walls
• These foam cells are larger than macrophages (white blood cell)
• These cause damage to the cell walls

Question 27

What is Pathogenesis Atherosclerosis?

Answer 27

• A progressive disease that affects CVD (Heart disease)

- This is basically just a build up of plaque inside your arteries

Question 28

What is the single best lipid predictor of CVD (Heart disease)?

Answer 28

• HDL (High density lipoprotein)