carbohydrates

Question 1

what are some types of polymers ?

Answer 1

carbohydrates
proteins
nucleic acids
(not lipids)

Question 2

define polymer

Answer 2

polymers are large, complex molecules composed of long chains of monomers joined together

Question 3

define monomer

Answer 3

monomers are small basic molecular units

Question 4

what are carbohydrates made from ?

Answer 4

monosaccharides and contain carbon, oxygen and hydrogen. C,H,O

Question 5

give examples of monomers

Answer 5

. monosaccharides
. amino acids
. nucleotides

Question 6

give the name of the three main monosaccharides

Answer 6

. glucose
. fructose
. galactose

Question 7

what type of sugar is glucose?

Answer 7

a hexose sugar

Question 8

what is a hexose sugar?

Answer 8

a monosaccharide with SIX carbon atoms

Question 9

what are the two types of glucose?

Answer 9

alpha and beta

Question 10

what are isomers?

Answer 10

molecules with same molecular formula but different molecular structure.

Question 11

where is the hydroxyl OH placed in Beta glucose?

Answer 11

at the top

Question 12

where is the hydroxyl OH placed in alpha glucose?

Answer 12

on the bottom

Question 13

draw a beta and alpha glucose

Answer 13

look at page 2 of revision guide!

Question 14

what is a condensation reaction ?

Answer 14

when two molecules join together to form a chemical bond and water is released.
monosaccharides are joined by condensation reactions, and glycosidic bond is formed.

Question 15

how are disaccharides formed ?

Answer 15

. a disaccharide is formed when two monosaccharides join together.

Question 16

how is the disaccharide maltose formed?

Answer 16

condensation reaction between glucose and glucose monosaccharides.
glucose + glucose—> =maltose + water

Question 17

how is the disaccharide sucrose formed?

Answer 17

condensation reaction between glucose and fructose monosaccharides.
glucose + fructose—> sucrose + water

Question 18

how is the disaccharide lactose formed?

Answer 18

condensation reaction between glucose and galactose monosaccharides.
glucose + galactose—> lactose + water

Question 19

describe a hydrolysis reaction

Answer 19

polymers can be broken down by hydrolysis reactions.
a hydrolysis reaction breaks the chemical bond between monomers using WATER.

Question 20

what is a general term for monosaccharides and disaccharides?

Answer 20

Sugar

Question 20

what are the two types sugars

Answer 20

reducing e.g (all monosaccharides e.g glucose, fructose and galactose and most disaccharides such as maltose and lactose)
and non reducing e.g sucrose

Question 21

describe how you would test for reducing sugars

Answer 21

1)add benedict’s blue reagent to sample( must be liquid if not grind up in water)
2) heat in a water bath that is boiled
3)positive result will show brick red or green, yellow for lower sugar

Question 22

how can you compare the amount of reducing sugar in different solutions?

Answer 22

filter solution
weigh precipitate

Question 23

describe test for non reducing sugars

Answer 23

1) get new sample of test solution( must be liquid if not grind up with water)
2)add dilute HCL (hydrochloric acid) and boil
3)neutralise with sodium hydrogen-carbonate because benedict’s doesn’t work in acidic conditions
4) retest with benedict’s and reheat in boiling water bath
5) positive will show orange brown, negative will show blue

Question 24

describe the test for starch

Answer 24

1) add 2cm of sample being tested in test tube
2) 2 drops add iodine dissolved in potassium iodide solution
3) presence of starch yellow to blue- black

Question 25

what are polysaccharides?

Answer 25

a polysaccharide is formed when more than two monosaccharides are joined together by a condensation reaction

Question 26

what is between the monosaccharides boned together?

Answer 26

a glycosidic bond

Question 27

where is starch found?

Answer 27

in plants, energy store of glucose

Question 28

describe the monomers in starch

Answer 28

. alpha glucose
. amylose unbranched, helix/coiled up making it more compact for better storage as it fits more 1-4 glycosidic bonds
. amylopectin highly branched allowing better access for enzymes to break down molecule so glucose is released quickly with 1-4 and 1-6 glycosidic bonds

Question 29

why is its structure suited for energy storage?

Answer 29

1) insoluble, doesn’t affect water potential, so water isn’t drawn out into cells by osmosis
2)helix in amylose 1-4 glycosidic bond makes it compact so it fits lots of glucose in small space
3)branched structure of amylopectin 1-4 & 1-6 glycosidic bond makes it highly branched increasing surface area for rapid hydrolysis into glucose

Question 30

where is glycogen found? what is the role?

Answer 30

.animals and bacteria, never in plants.
.mainly found in muscles and liver.
energy store of glucose used in respiration

Question 31

what is the monomer of glycogen ?

Answer 31

.alpha glucose

Question 32

why is it suited for the role of storing glucose in animals?

Answer 32

.1 insoluble, doesn’t affect water potential, stops water from entering cells via osmosis
.2 insoluble, doesn’t diffuse out to cells
3. highly highly branched structure increases surface are for rapid hydrolysis into a glucose

Question 33

where is cellulose found and what is its role?

Answer 33

. plant cell wall
. structural strength

Question 34

what monomer is cellulose made form ?

Answer 34

beta glucose

Question 35

describe the structure of cellulose

Answer 35

. long straight, unbranched chains.
.these chains are parallel to each other and linked with hydrogen bonds to form fibres called microfibrils.
.hydrogen bonds are individually weak but the amount of them make them collectively strong

Question 36

why is cellulose suited to its function?

Answer 36

.insoluble, doesn’t affect water potential
.b glucose form long, straight, unbranched chains
.many hydrogen bonds in microfibrils provide collective strength