Structure And Function Of Lipids

Question 1

Lipids:

- structure

Answer 1

3 fatty acids bound to glycerol called a triglyceride

Question 2

Glycerol:

- structure

Answer 2

Propane-1,2,3- triol

Question 3

Saturated vs unsaturated

Answer 3

Saturated lipids are solid fats, that contain only carbon single bonds and keep a compact structure
Unsaturated lipids are liquid oils, that contain some carbon single and double bonds that cause the fatty acid to be branched creating the oil

Question 4

Trans vs Cis fatty acids

Answer 4

Trans and acid are both unnatural, and consist of some carbon double bonds
Trans FA: elaidic acid
Via FA: oleoic acid
Full saturated form is called stearic acid

Question 5

Naming polyunsaturated FAs

Answer 5

Skeleton structure

18:1 signifies that the lipid is 18 carbons long and the 1 is the double bond of present

Question 6

Phospholipid:

- structure and function

Answer 6

2 FAs, glycerol, phosphate attached to an alcohol
Function: hydrophobic exclusion forces phospholipidsnintonparticualr higher level structures, a hydrophilic head and a hydrophobic tail
A Micelle is formed by detergent molecules
The phospholipids form a phospholipid bilateral

Question 7

Phospholipids:

- types

Answer 7

Phosphatidyl choline
Ethanolamine
Serine
Inositol 
Glycerol

Question 8

Triacylglycerols:

- melting point

Answer 8

Form a solid form by van der Waals interactions between the acyl chains
The presence of unsaturated FAs is a triacylgylcerol reduces the molecular lacking, so that less energy is needed for melting

Question 9

Oil transformation to fats

Answer 9

By hydrogenation of adding hydrogen across double bonds in the acyl chains (saturating the double bond)

Question 10

Fats:

- energy source

Answer 10

Can be used in mitochondria to form ATP, via conversion to acetyl CoA (by glycolysis)

Question 11

Lipid storage

Answer 11

Adipose cells

Question 12

Lipid energy output

Answer 12

9 kcal g-1

Question 13

Lipid characteristics

Answer 13

Water insoluble

Lipophilic

Question 14

Combination of many fatty acids to form a fat

Answer 14

Formation of an ester bond, allowing the formation of several layers or sheets

Question 15

Trans fats:

- diet and health

Answer 15

Increase CVD as there is an increase LDLs and a reduction in HDLs
Increase in trans fats consumption 2% equates to a 23% increase in CVD risk

Question 16

Lipid absorption

Answer 16

1. Bile salts emulsify dietary fats in SI forming micelles
2. Intestinal lipases degrade
   Triacylgylcerols
3. FAs and other prods taken up by intestinal mucus and converted to triacylgylcerols
4. Triacylgylcerols are incorp with cool and apolipoprots into chylomicrons
5. Chylomicrons move through lymph and blood to tissue
6. Lipoprot lipase convert triayclegylcerols to FAs and glycerol
7. FAs enter cells, are oxi as fuel or reesterified for storage

Question 17

Lipoprot lipase location

Answer 17

Attached to blood capillary walls

Question 18

Fatty acid oxidation:

- stages

Answer 18

1. Oxi conversion of 2-carbon units from the carboxyl end of the FAs into acetyl CoA (Beta oxi), accompany gem NADH and FADH2
2. Oxi of acetyl CoA in TCA gen NADH and FADH2
3. Oxi phospho; electrons transferred from NADH and FADH2 to O2 gen ATP

Question 19

Beta oxi

- location

Answer 19

Mitochondrial matrix:

• small FAs diffuse freely across mito mem
• larger FAs transporters via carnitine transporter

Question 20

Beta oxidation:

- overview

Answer 20

1. Dehydro; remove 2H, double bond at C2-3 FAD reduced (trans-2-wnoyl CoA)
2. Hydration; addition of water (L beta hydroxy acyl CoA)
3. Dehydro; remove 2H, NAD reduced (Beta ketoacyl CoA)
4. Thiolysis; formation of acetyl-CoA

Question 21

ATP

Answer 21

Adenosine Trios Phosphate

Question 22

Cholesterol absorption:

- small intestines

Answer 22

From intestinal lumen:

• facilitated diffusion of Na/gluc
• Na/gluc symporter
• brush border sucrase

Question 23

Cholesterol:

• hydrophobic effect
• characteristics

Answer 23

Forms a ball, hydrophilic outside and hydrophobic outside

Amphiphilic

Question 24

Cholic acid

- chemical structure

Answer 24

Many OH and COOH

Question 25

Triacylglycerol:

- consists of

Answer 25

Cholic acid + assoc with triacylglycerols forms a triacylglycerols

Question 26

Triacylglycerols:

- characteristics

Answer 26

Major energy store, highly reduced (38 JKg-1), anhydrous storage and stored in adipose cells
Linked by Ester bonds (linkages)

Question 27

Lipolysis:

- breakdown

Answer 27

Triacylglycerols breakdown into glycerol and FAs to be broken down to glucose in the liver and FAs to other tissues for B oxi

Question 28

Lipoproteins:

- structure

Answer 28

Contain triacylglycerols and cholesteryl esters, surrounded by phospholipids, cholesterol and apoplipoproteins

Question 29

Cholesterol:

- conversion

Answer 29

Chol + FAs + ATP —> cholesterol esters

Question 30

Cholesterol conversion:

- hormones

Answer 30

C18: oestrogen
C19: androgens
C21: gluco/mineralocorticoids (cortisol and aldosterone)