Lecture 5

Question 1

why are lipids hydrophobic?

Answer 1

because they have hydrocarbon chains

they are soluble in non-polar solvents (ether and chloroform)

Question 2

what are the 4 types of lipids and name their characteristics

Answer 2

1) triglycerides = water insoluble
2) fatty acids = water insoluble
3) steroids = membrane component, hormones
4) phospholipids = amphipathic, membrane component

Question 3

what is the main function of fats?

Answer 3

energy storage

also insulation against cold, cushion for injury

Question 4

what are the two small molecules that triglycerides are made up of?

Answer 4

1) fatty acids (3)
2) glycerol

Question 5

name

Answer 5

glycerol

Question 6

name

Answer 6

fatty acid

Question 7

what is an ester linkage?

Answer 7

3 fatty acids joined to 1 glycerol molecules through these bonds.

linkages in triaclyglycerol

Question 8

what are the three types of fatty acids?

Answer 8

1) saturated
2) monounsaturated
3) polysaturated

Question 9

mono, poly, saturated fatty acids

what is the difference between the types of fatty acids?

Answer 9

1) saturated = max # of hydrogen bonds with no double bond
2) monounsaturated = one double bond, liquid at room temperature
3) Polysaturated = contains more than one double bond, liquid at room temperature

Question 10

what type of shape can unsaturated fatty acids occur in?

Answer 10

trans or cis

Question 11

what type of unsaturated fatty acid is this?

Answer 11

trans

Question 12

what type of unsaturated fatty acid is this?

Answer 12

cis

Question 13

what are hydrogenated fats?

Answer 13

fats in which hydrogen atoms have been added to unsaturated fatty acid chains during the process of hydrogenation. This process converts cis-bonds into trans-bonds

example of margarine having more trans fatty acids than butter

Question 14

what is the use of bile salts made by the liver?

Answer 14

bile salts are used in the digestive tract that break down large fats

Question 15

Explain the process of the digestion of triglycerides

Answer 15

fats are hydrolyzed into fatty acids to be absorbed into the mucosal cells of the inner wall of the small intestine. These are then reassembled and packaged into lipoproteins called chylomicrons. These chylomicrons enter the blood to deliver fats to the cells of the body.

Simple terms:
1) fatty acids broken down in small intestine
2) bile salts from liver break down large fats
3) enzymes break down triglycerides
4) broken down triglycerides become lipoproteins that get stores in hollow spheres called chylomicrons
5) these chylomicrons are distributed to the rest of the body

Question 16

what are chylomircons?

Answer 16

hollow spheres that store lipoproteins which get distributed throughout the cells of the body
- have a hydrophobic interiror
- have a hydrophilic exteriror

Question 17

what are VLDLs?

Answer 17

very low density lipoproteins

Question 18

what is this process?

Answer 18

the breakdown and digestion of triglycerides and the distribution of lipoproteins in chylomicrons to the cells of the body

Question 19

what are steroids and name two.

Answer 19

steroids are 4 interconnected hydrocarbon rings with various functional groups attached.

ex: testosterone and cholesterol

Question 20

what are anabolic steroids?

Answer 20

steroids used to promote muscle growth

Question 21

how is cholesterol transported in the blood?

Answer 21

by lipoproteins (LDL and HDL)

Question 22

what is considered bad cholesterol?

Answer 22

diets that are high in trans fats that impede the uptake of low density lipoproteins by cells which cause the low density lipoproteins to continue circulating the blood.

the more LDL you have circulating the blood, the higher the risk of blocked arteries = atherosclerosis

Question 23

what is considered good cholesterol?

Answer 23

the amount of high density lipoproteins circulating the blood; HDLs pick up excess cholesterol and take it to the liver to get processed which reduces the amount of cholesterol in the blood.

Question 24

what does it mean when you have a higher ratio of LDL/HDL?

Answer 24

higher risk of cardiovascular disease

Question 25

what does diets in high saturated and trans fats cause?

Answer 25

• increased LDL levels
• decreased HDL levels
• increased triglyceride levels

Question 26

what do diets in omega-3 and omega-6 fatty acids seem to have?

Answer 26

an increase in HDL-cholesterol levels

Question 27

which omega is this?

Answer 27

omega-6

omega-6 indicates that the last double bond is 6 carbons away from the last carbon.

Question 28

which omega is this?

Answer 28

omega-3

omegaa-3 indicates that the last double bond is 3 carbons away from the last carbon

Question 29

phospholipids

what is cholin used for?

Answer 29

cholin is a molecule that contains nitrogen that is linked to phosphate groups to create phospholipids

Question 30

true or false

phospholipids are amphipathic

Answer 30

TRUE
they have non-polar hydrophobic tails ( fatty acids) and a polar hydrophilic head ( glycerol, phosphate and organic base)

amphipathic = contains both polar and non polar structures

Question 31

what are cell membranes composed of?

Answer 31

phospholipid bilayer

Question 32

what are the two types of phospholipid bilayers?

Answer 32

1) phosphoglycerides (contain glycerol, fatty acids, phosphate and alcohol)
2) sphingolipids (contains a sphingosine)

sphingosine = long chain of amino alchohol instead of glycerol

Question 33

phospohoglyceride or sphingolipid?

Answer 33

sphingolipid

Question 34

phospohoglyceride or sphingolipid?

Answer 34

phoshoglyceride

Question 35

where do sphingolipids occur?

Answer 35

they occur in high concentrations in the brain, nerves, lungs and spleen tissue.

they are a large component of the myelin sheath surrounding nerve cells

Question 36

what are tay-sachs?

Answer 36

accumulation of sphingolipids

produced by the cell for recognition and cell-cell signaling