2.3 Carbohydrates and lipids

Question 1

Monosaccharides

Answer 1

single sugar units

Question 2

Examples of monosaccharides

Answer 2

glucose, fructose and ribose

Question 3

Disaccharides

Answer 3

consists of two monosaccharides linked together

Question 4

Examples of disaccharides

Answer 4

maltose - two glucose molecules
sucrose - glucose and fructose
lactose - glucose and galactose

Question 5

Polysaccharides

Answer 5

consist of many monosaccharides linked together

Question 6

Examples of polysaccharides

Answer 6

starch - long chains of alpha-glucose molecules
glycogen
cellulose

Question 7

What are the two types of starch?

Answer 7

amylopectin

amylose

Question 8

Condensation reactions

Answer 8

the building of large macromolecules (polymers) by the removal of water molecules when monomers combine

Question 9

Hydrolysis reactions

Answer 9

the break down of larger polysaccharides into smaller monosaccharides through the addition of water

Question 10

Celllulose

Answer 10

unbranched chains of beta-glucose, held together by glycosidic bonds

Question 11

Glycogen

Answer 11

energy storage polysaccharides formed in the liver in animals
composed of alpha-glucose subunits linked together by 1-4 linkages and 1-6 linkages (branching)

Question 12

Amylose

Answer 12

linear (unbranched) molecule and harder to digest, less soluble
helix
1, 4 linkages

Question 13

Amylopectin

Answer 13

branched chains
globular
1, 6 linkages

Question 14

Fatty acids

Answer 14

long hydrocarbon chains that are found in certain types of lipids (triglycerides and phospholipids)

Question 15

Saturated fatty acids

Answer 15

possess no double bonds
originate from animal sources
solid at room temperatures

Question 16

Unsaturated fatty acids

Answer 16

bent in structure
originate from plant sources
liquid at room temperature

Question 17

What are the two types of unsaturated fatty acids?

Answer 17

cis isomers

trans isomers

Question 18

Cis isomers

Answer 18

the hydrogen atoms attached to the carbon double bond are on the same side

Question 19

Trans isomers

Answer 19

the hydrogen atoms attached to the carbon double bond are on different sides
do not occur in nature

Question 20

Differences between cis and trans isomers

Answer 20

cis - bent at the end of the double bonds
trans - do not have a bent at the double bond

cis - lower melting points
trans - higher melting points

cis - liquid at room temperature
trans - solid at room temperature

trans - healthier for humans

Question 21

Triglycerides

Answer 21

largest class of lipids and function as long-term energy storage molecules

Question 22

How are triglycerides formed?

Answer 22

condensation reactions occur between one glycerol and three fatty acids

Question 23

Advantages of using lipids rather than carbohydrates

Answer 23

lipid releases more energy from cell respiration
lipids have secondary roles that could not be performed as well by carbohydrates (poor conductors of heat, liquid at room temp)

Question 24

Why is glycogen used for short-term storage?

Answer 24

can be broken down to glucose rapidly and transported easily by the blood

Question 25

What are the health risks of saturated fatty acids?

Answer 25

Positive correlation between saturated fatty acids intake and rates of CHD; there are populations that do not fit the correlation
Actual cause of CHD is not saturated fat itself
Low rates of CHD in the population is due to intake of cis-monounsaturated fatty acids

Question 26

What are the health risks of trans-fatty acids?

Answer 26

A positive correlation between amounts of trans-fat consumed and rates of CHD; trans-fats are cause of CHD
Patients who died from CHD: fatty deposits contained high concentrations of trans-fats

Question 27

How can scientific evidence be evaluated?

Answer 27

correlations, surveys and sample size