6: Biochemistry - Lipid catabolism

Question 1

What is the accurate name for a fat cell?

Answer 1

Adipocyte

Question 2

Increased fat intake without appropriate energy expenditure leads to (an increase / a decrease) in the number and fat content of adipocytes.

Answer 2

an increase

Question 3

Fat is an important source of ___.

Answer 3

energy

Question 4

What name is given to fatty acids which are required for body function but aren’t synthesised within the body itself?

Answer 4

Essential fatty acids

Question 5

Absorption of which important molecules is closely associated with fat absorption?

Answer 5

Vitamins (A,D,E,K)

Question 6

Give two examples of simple lipids.

Answer 6

Fatty acids

Triglycerides

Question 7

Which compound lipids transport fats in the plasma?

Answer 7

Lipoproteins

Question 8

Which group of lipids includes cholesterol** and hormones?

Answer 8

Steroids

Question 9

Lipids are (carbohydrates / hydrocarbons).

Answer 9

hydrocarbons

Question 10

Lipids are (soluble / insoluble) in water.

Answer 10

insoluble

Question 11

Are lipids hydrophilic or hydrophobic?

Answer 11

Hydrophobic

remember that they’re insoluble in water

Question 12

Which type of lipid is the primary storage molecule for fat?

Answer 12

Triglyceride

Question 13

What are the four main components of a triglyceride molecule?

Answer 13

Glycerol

3 fatty acids

Question 14

Molecules around a C=C double bond in fatty acids tend to be of a (cis / trans) configuration.

Answer 14

cis

Question 15

Essential fatty acids tend to be (saturated / unsaturated / polyunsaturated).

Answer 15

polyunsaturated

Question 16

What are the three main products of triglyceride digestion?

Answer 16

Fat is digested into:

glycerol

fatty acids

monoglycerides

Question 17

In which cells is glycerol absorbed in the GI tract?

Why can it be absorbed so early compared to fatty acids?

Answer 17

Intestinal epithelial cells

Glycerol is hydrophilic, fatty acids are hydrophobic

Question 18

In which cells are fatty acids and monoglycerides absorbed in the GI tract?

Answer 18

Intestinal mucosal cells

Question 19

After their absorption into intestinal mucosal cells, how are long chain fatty acids and monoglycerides prepared for transport in the blood?

Answer 19

Converted back into triglycerides

Question 20

Dietary fats (i.e digested fat - fatty acids and triglycerides) are transported in the blood as ___.

Answer 20

chylomicrons

cholesterol and protein are added on

Question 21

What is a chylomicron?

Answer 21

A transport vessel for dietary fat, made of protein and cholesterol

Question 22

Which enzyme cleaves chylomicrons to release the fatty acids and triglycerides it contains?

Answer 22

Lipoprotein lipase

Question 23

Which cells require the breakdown of chylomicrons to use the fatty acids and triglycerides?

Which cells use each product?

What is each product used for?

Answer 23

Adipose cells and Muscle cells

Adipose cells use the triglycerides

Muscle cells use the fatty acids

Triglycerides are STORED in adipose cells

Fatty acids are OXIDISED in muscle cells

Question 24

What happens to fatty acids in adipose cells?

Answer 24

Resynthesised into triglycerides

Stored

Question 25

What happens to fatty acids in **muscle cells**?

Answer 25

**Oxidised for energy**

Question 26

What is **lipolysis**?

Answer 26

**Breakdown of lipids**

Question 27

Which type of enzyme **cleaves** triglycerides to release fatty acids and glycerol?

Answer 27

**Lipases**

Question 28

Which emergency hormone regulates the effects of **lipases**?

Answer 28

**Adrenaline** i.e fat is broken down for oxidation when it is needed, fight or flight

Question 29

Can fatty acids be oxidised immediately to generate energy? Why?

Answer 29

**No** They can't pass through the mitochondrial membrane (hydrophobic) so they require a carrier

Question 30

How are fatty acids modified in the cytoplasm before their transport to the mitochondria for oxidation?

Answer 30

**CoA** added to form **acyl-CoA**

Question 31

How much ATP is required to add **CoA** to a fatty acid molecule?

Answer 31

**2 ATP**

Question 32

Which **group** transports acyl-CoA across the mitochondrial membrane?

Answer 32

**Carnitine** technically CoA doesn't pass across but why the fuq would we need to know that for mbchb medicine

Question 33

Each round of **beta oxidation** (oxidation of fatty acids in the mitochondria) generates electron ___ which can generate energy via the cytochrome system.

Answer 33

**carriers** like NADH and FADH

Question 34

Oxidation of fatty acids with funny structures requires the catalysis of additional \_\_\_.

Answer 34

**enzymes**

Question 35

What byproduct is produced by the digestion of **glycerol**?

Answer 35

**Ketone bodies**

Question 36

What is the fate of acetyl-CoA generated from fatty acid oxidation?

Answer 36

**Enters TCA cycle** and is oxidised

Question 37

Which ketone usually deals with Acetyl-CoA in the TCA cycle?

Answer 37

**Oxaloacetate**

Question 38

During **prolonged starvation**, what happens to oxaloacetate?

Answer 38

**It is consumed for gluconeogenesis**

Question 39

What accumulates in the body of someone with **diabetes** or **prolonged starvation**?

Answer 39

Acetyl CoA because no oxaloacetate is around to deal with it

Question 40

**Acetyl-CoA** is **(acidic / alkaline****)**.

Answer 40

**acidic**

Question 41

What is the condition caused by accumulation of **acetyl-CoA** in the body?

Answer 41

**Ketoacidosis**