Lipids Biochemistry

Question 1

What is xanthelasma?

Answer 1

Yellow deposit of cholesterol underneath the skin. Usually on or around the eyelids

Question 2

What is xanthelasma result of?

Answer 2

High levels of cholesterol in bloodstream

Question 3

Describe cholesterol

Answer 3

White crystalline

Soft yellow appearance

Question 4

What chemical group does cholesterol contain and why is this important?

Answer 4

Hydroxyl group

Very fat soluble

Question 5

Are the rings of cholesterol planar?

Answer 5

NO

Question 6

What is “stacking”?

Answer 6

Sit on top of each other

Question 7

Can cholesterol stack?

Answer 7

YES

Forms crystals in blood + urine

Question 8

What happens when cholesterol is in the blood?

Answer 8

Cause precipitation
Coagulation
Blood vessel blockage
Heart disease

Question 9

How do you form cholesterol?

Answer 9

3 molecules of acetic acid activated
Becomes acetyl CoA
Combine using HMG-CoA reductase 
Form mevalonic acid
Converted to cholesterol

Question 10

What is HMG-CoA reductase?

Answer 10

Enzyme in mevalonic acid pathway (produce cholesterol)

Question 11

What do drugs do that lower cholesterol?

Answer 11

Inhibit HMGCR = lower serum cholesterol = reduce cardiovascular diseases

Question 12

What are examples of statins

Answer 12

Lovastatin (Mevacor)
Fluvastatin (Lescol)
Pravastatin (Pravachol)
Atorvastatin (Lipitor)

Question 13

Describe statins

Answer 13

All share similarities with mevalonic acid

Block HMG-CoAR

Question 14

What are the best statins + why?

Answer 14

Rosuvastatin, Pitavastatin + Atorvastatin

= tightest bound to enzyme = best at reducing cholesterol

Question 15

What is acetic acid?

2 carbon

Answer 15

Vinegar

Question 16

When are fatty acids saturated?

Answer 16

C=O

Question 17

When are fatty acids unsaturated?

Answer 17

C=C

Question 18

What can long chain fatty acids do?

Answer 18

Stack = form crystalline solids

Question 19

Why is olive oi liquid at RT?

Answer 19

Contains oleic acid
= cis C=C 
= "kink" in the chain
= no stacking
= no crystalline solid

Question 20

What do solid fats do?

Answer 20

Form clots in blood vessels more readily than liquid fats

Question 21

What do trans fats do?

Answer 21

For straight chain fatty acids
= stack
= form crystalline solids

Question 22

What do manufactures do to make their food crispy?

Answer 22

Convert unsaturated CIS oil + convert into solid tarns fats

Process = hydrogenation

Question 23

What are triglycerides?

Answer 23

3 fatty acids combined with glycerol

Question 24

Are triglycerides inert?

Answer 24

YES BUT esters “unstable”

= can be reversibly broken down

Question 25

How are triglycerides broken down?

Answer 25

1st ----> 2nd ----> 3rd | Then glycerol left

Question 26

What is the process of breaking down triglycerides regulated by?

Answer 26

Epinephrine (adrenaline)

Question 27

What is a mixed triglyceride?

Answer 27

2 saturated fatty acids attached to one unsaturated fatty acid

Question 28

What are lipoproteins?

Answer 28

Complex particles with central core containing cholesterol esters + triglycerides surrounded by free cholesterol, phospholipids + apolipoproteins, which facilitate lipoprotein formation + function

Question 29

What are apolipoproteins?

Answer 29

Proteins that bind to lipids

Question 30

What are lipoproteins spheres?

Answer 30

Allow for unreactive transport of lipids | = smallest SA = less area for it to react

Question 31

What are the 4 classes of lipoproteins?

Answer 31

``` Chylomicrons Very-low density lipoproteins (VLDL) Low-density lipoproteins (LDL) Intermediate density lipoproteins (IDL) High-density lipoproteins (HDL) ```

Question 32

How much lipid in chylomicrons?

Answer 32

99%

Question 33

How much lipid in VLDL?

Answer 33

85%

Question 34

How much lipid in LDL?

Answer 34

82%

Question 35

How much lipid in IDL?

Answer 35

80%

Question 36

How much lipid in HDL?

Answer 36

50%

Question 37

Why do the high density lipoproteins have less fat?

Answer 37

Proteins denser than fats

Question 38

Describe absorption in small intestine

Answer 38

Through striated border epithelium covering villi | Diffusion + active transport

Question 39

What is absorbed into capillaries?

Answer 39

Amino acids, sugars, minerals, glycerol, some fatty acids + vitamins

Question 40

What is absorbed into lacteals?

Answer 40

Glycerides, some fatty acids + fat soluble vitamins

Question 41

What do fatty acids + triglycerides do in the intestine?

Answer 41

Form emulsion | = achieved by bile secretion

Question 42

What happens to fats in intestine?

Answer 42

Emulsion forms micelles Micelles approach cells of intestine wall + collapse Fats + triglycerides absorbed into epithelial cells Chylomicrons pass into lymph system

Question 43

What are bile salts made from?

Answer 43

Cholesterol

Question 44

How do LDL contribute to heart disease?

Answer 44

Transported through blood Stick yo blood vessels Absorbed by cell wall of blood vessel = its oxidised

Question 45

How does our body try to protect from oxidised fats?

Answer 45

Engulf with macrophages | "blow up" in size = foam cell

Question 46

What happens when foam cell trapped in protein matrix of blood vessel wall?

Answer 46

Form lump distorts blood vessel Makes lumen narrower Lump = plaque Process = atherosclerosis

Question 47

Describe atherosclerosis

Answer 47

Plaque with fibrous cap Cap ruptures Blood clot forms around rupture = blocks artery

Question 48

Where are bile salts produce from?

Answer 48

Gall bladder

Question 49

What is the problem with bile salts being made from cholesterol?

Answer 49

For crystals = gall stones = block gall bladder