Lecture 4 - Lipids

Question 1

What are lipids ?

Answer 1

Large bio molecules
NOT polymers
Largely non polar and insoluble in water
Hydrophobic interactions causing grouping in water

Question 2

Describe the function and structure of a triglyceride

Answer 2

A glycerol backbone with three fatty acid chains attached which are linked via Ester bonds Formed via dehydration Reactions
Broken down by hydrolysis requiring intestinal triglyceride lipase and water

Question 3

Describe fatty acids

Answer 3

Saturated - single bonds - compact and solid at room temp
Unsaturated - double bonds /at least one - this forms a kink in the chain which can affect the solubility further - loosely packed due to cis double bonds and liquid at room temp

Question 4

Describe steroids and give an example

Answer 4

4 fuses carbon rings with various side groups
Lanosterol is the building blocks formed by the cyclisation of squalene
E.g cholesterol , sex hormones , corticosteroids, vitamin D

Question 5

Describe phospholipids

Answer 5

Lipids with a phosphate group covalently bonded to a glycerol backbone
Phosphate is polar and can have a variable chain
They form the phospholipid bilayer

Question 6

What is a Micelle

Answer 6

Spherical arrangement of lipid molecules

Question 7

Describe glycolipids

Answer 7

A lipid covalently bonded to an oligosaccharide which forms part of the cell membrane and glycocalyx

Question 8

Describe lipoproteins

Answer 8

Soluble complexes that transport lipids which are synthesised in the liver
Spherical particles with a central hydrophobic core q

Question 9

Describe apoproteins

Answer 9

Stabilise structure and regulate enzymatic activity at the lipoprotein interface

Question 10

What are the main apoproteins for chilomicrons, VLDL, IDL,LDL AND HDL

Answer 10

B-48, E, E, B-100, A-1

Question 11

Describe VLDL lipoproteins

Answer 11

Very low density lipoproteins

Produced in the liver from synthesised triglycerides and cholesterol esters to carry fat to target tissues

Question 12

Describe HDL lipoproteins

Answer 12

Carries cholesterol to the liver , reducing atherosclerosis

Question 13

What is adipose tissue and what is stored there ?

Answer 13

Triglycerides are stored as fatty acids in apodocyte cells in apodocyte tissue which is essentially fatty tissue with two types white and brown

Is is an endocrine organ producing pro inflammatory hormones which promote blood clotting

Question 14

Describe white adipose tissue

Answer 14

Gives insulation and cushions internal organs and reduces heat loos from skin - primarily found beneath the skin

Question 15

Describe brown adipose tissue

Answer 15

Has lots of mitochondria which produces heat as a waste product of respiration
Useful for generating body heat and are mainly found in shoulder blades, kidneys, spinal chord And around main internal organs

Question 16

What is excess adipose tissue associated with ?

Answer 16

Thrombosis, stenosis and aneurysms

Question 17

Describe vitamin A, D,E,K

Answer 17

A is retinol
D is cholecaliciferol - helps with Ca2+ absorption
E is tocopherol - antioxidant
K is phylloquinone - coagulation

Question 18

Describe hormones

Answer 18

Chemical messengers

Steroidal hormones are derived from cholesterol and eicosa pods are derived from omega 3 and 6

Question 19

Describe two factors reducing moisture loss

Answer 19

Lipids layers reduces skin moisture loss and lipid later on year film on eye reduces moisture loss from the cornea