carbs and lipids

Question 1

monomers =

Answer 1

smaller units from which larger molecules are made

Question 2

polymers =

Answer 2

molecules made from a large no. of monomers joined together

Question 3

condensation reaction =

Answer 3

joining two molecules, creating a chemical bond & removing a molecule of water

Question 4

hydrolysis reaction =

Answer 4

breaks a chemical bond between 2 molecules & involves the use of water

Question 5

hydrophobic =

Answer 5

repels water

Question 6

elements in carbs

Answer 6

C, H, O

Question 7

monosaccharides

Answer 7

monomers which form larger carbs

Question 8

common monosaccharides

Answer 8

•glucose
•galactose
•fructose

Question 9

isomer =

Answer 9

same molecular formula, diff. structure

Question 10

what are glucose’s 2 isomers?

Answer 10

•alpha glucose (H, OH)
•beta glucose (OH, H)

Question 11

disaccharides =

Answer 11

2 monosaccharides joined together by a glycosidic bond, formed by a condensation reaction

Question 12

disaccharide formulas

Answer 12

•glucose + glucose —> maltose + water
•glucose + galactose —> lactose + water
•glucose + fructose —> sucrose + water

Question 13

polysaccharides

Answer 13

created by condensation reactions between many glucose monomers

Question 14

starch (polysaccharide)

Answer 14

•monomer = alpha glucose
•bonds between monomers = 1-4 glycosidic bonds (amylose),1-4 & 1-6 glycosidic bonds (amylopectin)
•function = stores glucose
•location = plant cells
•struc. = amylose —> unbranched helix, amylopectin —> branched molecules
•how the struc. helps the function =
-insoluble —> water potential not affected
-amylose —> helix can compact to fit lots of glucose in a small space
-amylopectin —> branched so increases S.A for rapid hydrolysis back to glucose

Question 15

cellulose (polysaccharide)

Answer 15

•monomer = beta glucose
•bonds between monomers = 1-4 glycos. bonds
•function = structural strength in cell walls
•location = plant cell walls
•struc = polymer forms long straight chains —> chains held in parallel by many H bonds, forming fibrils
•how the struc helps thr functions =
-insoluble —> water potential not affected
- the many H bonds provide collective strength

Question 16

glycogen (polysaccharide)

Answer 16

•monomer = alpha glucose
•bonds between monomers = 1-4 & 1-6 glycos. bonds
•function = stores glucose (energy)
•location = animals (mainly in muscle & liver cells)
•struc = highly branched & coiled molecule
•how the struc helps the function =
-insoluble —> water potential not affected
-branched struc —> increases S.A for rapid hydrolysis back to glucose

Question 17

saturated =

Answer 17

contains only single bonds

Question 18

unsaturated =

Answer 18

contains at least one C=C double bond

Question 19

elements found in lipids

Answer 19

C, H, O, P

Question 20

name the two types of lipids

Answer 20

•triglycerides
•phospholipids

Question 21

the formation of triglycerides

Answer 21

-formed via a condensation reaction between 3 fatty acids + 1 glycerol (1 glycerol = three hydroxyl groups attached to one carbon)
-an ester bond is formed between the glycerol & each fatty acid
(R groups of fatty acids may be saturated or unsaturated)

Question 22

functions of triglycerides (& how they relate to the structure)

Answer 22

• energy storage —> large ratio of energy-storing carbon-hydrogen bonds
• metabolic water source —> can release water if oxidised > high ratio of hydrogen to oxygen atoms
• water potential stays same —> large & hydrophobic

Question 23

formation of phospholipids

Answer 23

-formed via condensation reactions between 1 glycerol + 2 fatty acids
-has phosphate group too

Question 24

function of phospholipids

Answer 24

• form bilayer —> head = hydrophilic (attracts water bc it’s charged) so head is exposed to water, fatty acid tail = hydrophobic (repels water bc of no charge)
• h20 soluble substances can’t pass through centre of bilayer —> hydrophobic

Question 25

test for starch

Answer 25

1. add iodine
2. colour change to blue/black

Question 26

test for reducing sugar

Answer 26

1. (mash sample if solid)
2. heat w benedicts reagent
3. colour change to red

Question 27

test for non-reducing sugars

Answer 27

1. heat w benedicts —> no colour change
2. add dilute hcl (hydrolyses glycosidic bond)
3. then add sodium hydrogen carbonate (neutralises sol.)
4. heat w benedicts —> colour change to red

Question 28

test for lipids

Answer 28

> add ethanol, then water + shake
milky emulsion

Question 29

use of a colourimeter to improve the repeatability of results

Answer 29

• quantitative
• standardises the method