lipids

Question 1

In triacylglycerols the fatty acid is attached to the glycerol molecule using which type of bond?

Answer 1

“ESTER BONDS: 3 carbon chains attached to a glycerol, Join FAs using ester bond to glycerol, Usually different FAs on each glycerol

Question 2

What are the two most common head groups of phospholipids?

why?

Answer 2

serine and choline because their charges balance with the phosphate. Ethanolamine is also a phospholipid head group.

Question 3

Why do humans need essential fatty acids?

Answer 3

We need essential fatty acids as humans can’t insert double bonds beyond n-9. We need these double bonds close to omega carbon (carbon on the tail of the FA), as we need to fold and convert this fatty acid into something else.

Question 4

how does cholesterol maintain the fluidity of cell memebrane at different temp?

Answer 4

HIGH TEMP - maintains memebrane integrity preventing more fluidity
LOW TEMP - prevents crystalisation and fatty acid association (not too rigid) of membrane

Question 5

Where is the carboxylic acid group (COOH) situated in a fatty acid?
A in the middle 
B at the head of the FA 
C at the tail of the FA 
D one third of the way down the FA 
E two thirds of the way down the FA

Answer 5

Carboxyl group (COOH) at one end (head of FA)

Question 6

what is most common number for carbon chain length and pka of fatty acid
A 12-20 // 2.8-4
B 16-18 // 4.7-5
C 12-16 // 2.8-4
D 14-16// 4.7--5

Answer 6

16- 18 and pka = 4.7-5

Question 7

how does chain lenght and saturation influence the melting point of FA?

Answer 7

longer the length, the higher the melitng point as there are more vanderwalls forces
> more electrostatic interactions
more saturated, less double bonds there are so higher melting point
> (vice versa) double bonds kink the chain wakening electrostatic interactions loweirng melt point

Question 8

stearic aicd has what ratio of carbon:double bond?

A 16:0
B 18: 0
C 18:1 (n-9)
D 18:3 (n-3)

Answer 8

> most common SATURATED FA ~ butter

so 18:0

Question 9

name essential fatty acids

omega..

Answer 9

omega 3 - alpha linoleic acid 18:3 n-3
omega 6 - linoleic acid 18:2 n-6
» arachadonic acid becomes essentiral if DEFICIENT in omega 6

Question 10

what is the ideal ratio for omega 3 and omega 6?

> eat your fish lads!

Answer 10

2:1 - 4:1 ratios!

but modern diets do not get enough

Question 11

what is a spingolipid? give an example of one

Answer 11

FA + amine alcohol (sphingosine) instead of glycerol
myelin sheath!
> spingososine + FA = ceramide –> glycolipid is ceramide and carb
SO glycolpids have a sphingolipid base!!!

Question 12

give the basic steroid structure

Answer 12

3x hexagon
1x pentagon
> inhibited by statins, many hormones (sex and cortisol)

Question 13

what is a good source of mega 3

Answer 13

oily fish! 2wice a week lads!

Question 14

lipopolysaccharide and glycolipid difference

Answer 14

needs polysaccharide -LONG CHAIN with lipid

glycolipids - any carb attatched to lipid so can be SMALL

Question 15

Which of the following is not a function of TAGs?
A Insulation
B Protection
C Form myelin sheath
D Energy store

Answer 15

OPTION C

Sphingomyelin is the lipid that forms myelin sheath!!
> eey i knew that!

Question 16

What is the most common monounsaturated fatty acid?
Stearic acid
Palmitic acid
Oleic acid
Linoleic acid 
Arachidonic acid

Answer 16

OPTION C
oleic acid as seen in plant oils
18:1 (n-9)`

Question 17

What is Palmitic acid also known as?
Octadecanoic acid
Hexadecanoic acid
cis-Δ9- Octadecanoic acid
Octadectrienoic acid
Eicosatetraenoic acid

Answer 17

OPTION B

got 16 carbons hence the hexa-

Question 18

Which of the following does not use cholesterol as a precursor?
Sex hormones
Glucocorticoids
Mineralocorticoids
Vitamin B
Bile salts

Answer 18

OPTION D

Vitamin D is a cholesterol precursor - acts as a steroid hormone!

Question 19

Which of the following does not use terpenoids as a precursor?
Vitamin A
Vitamin K
Ubiquinone
Bile salts
Co-enzyme Q

Answer 19

OPTION D

bile salts use cholsetol/steroid precursors