U4O2 Carbohydrates

Question 1

Carbohydrates

Answer 1

• Compounds composed of Carbon, Hydrogen, and Oxygen with the General formula Cx(H2O)y
• Also known as saccharides due to their sweet taste
• smaller carbohydrates are often referred to as sugars
• they provide a source of energy, a way of storing energy, structural material (plants)

Question 2

monosaccarides

Answer 2

simplest carbohydrates, also known as simple sugars, e.g. fructose

They are usually colorless, water-soluble, and crystalline solids.

Question 3

formation of disaccharides and polysacchrides

Answer 3

adjacent OH groups of two molecules join together through condensation reaction with an ether link between each monomer

Question 4

core monosacchiarides

Answer 4

Glucose - manufactured by plants for energy transfer and storage

Fructose - often found in fruit, also a source of energy

Galactose- not found free in nature but is a component of many larger carbohydrates like lactose

Question 5

glucose + glucose =>

Answer 5

Maltose + water

Question 6

glucose + fructose=>

Answer 6

Sucrose + water

Question 7

Glucose + galactose =>

Answer 7

Lactose + water

Question 8

determining molar mass of saccarides

Answer 8

n = number of monosaccharides

180Xn - 18(N-1)

Question 9

starch

Answer 9

energy storage component for plants

made from condensation of Alpha glucose

two main forms: Amylose and Amylopectin

Question 10

Amylopectin

Answer 10

occasional cross-links between glucose molecules - reaction occurs b/w -OH groups and C1 and C6 on neighboring sections of the chain

less effective packing and hence attraction between OH groups

weaker H-bonds b/w glucose molecules and make it more soluble and easier to break down

Higher GI foods contain amylopectin

Question 11

Amylose

Answer 11

linear polymer that packs well together

more effective packing and hence attraction b/w -OH groups

stronger H-bonds b/w glucose-> less soluble and break down for the body

Lower GI foods contain more Amylose

Question 12

Glycogen

Answer 12

energy and storage structure in humans and animals

formed from Alpha glucose also but is highly branched

we convert the glucose into glycogen and store it in the liver and muscle cells

Question 13

Cellulose

Answer 13

structural material found in plants

formed from polymerization of B-glucose

the tightly packed structure that leads to strength as a plant fibre

the human body is unable to break it down as we lack enzyme to do so

Question 14

Aspartame

Answer 14

one of the most common artificial sweeteners and is produced when aspartic acid, phenylalanine and methanol are combined through condensation

provides same energy per gram to many common sugars BUT is significantly sweeter

far less can be used to sweeten -> reduction in overall energy provided

Question 15

Triglycerides (fats and oils)

Answer 15

• are esters containing C, H and O
• includes fats, oils and waxes
• formed from condensation between glycerol and three fatty acids
• can be broken down into glycerol and fatty acids by hydrolysis

Question 16

saturated fatty acids

Answer 16

all single bonds b/w carbon atoms: general formula = CnH2n-1COOH

most animal fats are saturated and solids at room temperatures

Question 17

Mono-unsaturated fatty acids

Answer 17

1 Carbon double bond: General formula = CnH2n-1COOH

most plant oils are unsaturated and liquids at room temperature

double bond puts bend in chain that limits close packing of the molecules

Question 18

Poly-unsaturated fatty acid

Answer 18

More than 1 carbon to carbon double bonds

Question 19

Hydrolysis of triglycerides

Answer 19

• broken down into glycerol (for energy or for adipose storage) and fatty acid (energy)
• requires water and enzymes
• 3 water molecules are required
• in presence of enzyme so activation energy is lowered sufficiently for hydrolysis to occur at sufficient rate

Question 20

Essential fatty acids

Answer 20

fatty acids the body cannot synthesize and must be obtained from dietary intake or from nature

e.g. omega-3 and omega-6

Question 21

Non-essential fatty acids

Answer 21

Fatty acids the body is able to synthesize

e.g. linoleic and linolenic acids

Question 22

Omega-3 VS Omega-6

Answer 22

both are named from the position of the first carbon double bond from the methyl end of the chain

6: increase blood pressure, immune response, inflammation
3: heart-healthy effects

Question 23

Cis/trans-fats

Answer 23

rarely occur in nature but can be artificially produced

Trans fats = used in fast food b/c cheaper, had desirable melting point and resisted rancidity

Question 24

Rancidity

Answer 24

breakdown in flavour or aroma in fats/oils

notable deterioration in taste or smell

can be oxidative, microbial or hydrolytic

unsaturated fats are less stable than saturated ones-> can react in a number of ways with enzymes, heat, water, oxygen or light

Question 25

Oxidative rancidity

Answer 25

breakdown of fats and oils in presence of oxygen

most common type = autoxidation

higher degree of unsaturation = more susceptible to oxidation

leads to formation of aldehydes and ketones

Question 26

Vitamins

Answer 26

essential to our diet but in lower proportions- prevent various diseases such as scurvy

usually essential and not made in human body except vitamin D

Question 27

Water soluble vitamins

Answer 27

higher proportion of OH groups

not retained as stored in the aqueous environment of the blood

Diet needs to regularly intake of water-soluble vitamins

Question 28

Fat soluble Vitamins

Answer 28

long hydrocarbon chains but are low in -OH groups compared to water-soluble vitamins

stored in fat as fats are also formed from long organic chains

Question 29

slowing rancidy

Answer 29

Vacuum packing or using nitrogen

filling containers up to the lid

storing food in the dark and cold

restricting access to copper, iron, and nickel