12.1 Carbohydrates

Question 1

What is a monomer?

Answer 1

Small identical / similar molecules which can be condensed to make larger molecules called polymers.

Question 2

What is a polymer?

Answer 2

Large molecules made from joining 3 or more small identical / similar monomers together. Using covalent bonds.

Question 3

What is a condensation reaction?

Answer 3

Joins 2 monomer units together with the removal of 1 water molecule which forms a bond.

Question 4

What is a hydrolysis reaction?

Answer 4

The addition of 1 molecule of water to break the bond between 2 monomers.

Question 5

3 monomers

Answer 5

Monosaccharides (alpha and beta glucose), amino acids and nucleotides.

Question 6

3 polymers

Answer 6

Polysaccharides, Polypeptide / protein, polynucleotide or nucleic acid

Question 7

Polysaccharide examples

Answer 7

starch, cellulose, glycogen.

Question 8

nucleic acid examples

Answer 8

DNA, RNA

Question 9

Bond between monosaccharides and polysaccharides

Answer 9

glycosidic bonds

Question 10

polypeptide / protein examples

Answer 10

enzymes, haemoglobin

Question 11

Bond between amino acids and polypeptide / protein

Answer 11

peptide bonds

Question 12

Bond between nucleotides and polynucleotide / nucleic acid

Answer 12

phosphodiester bonds

Question 13

Elements in carbohydrates

Answer 13

carbon, hydrogen, oxygen

Question 14

ratio of elements in carbohydrates

Answer 14

H:O = 2:1 AND C:O = 1:1

Question 15

generic formula for carbohydrates

Answer 15

(CH2O)n when n = 3 to 6

Question 16

carbohydrates monomers

Answer 16

monosaccharides

Question 17

creation of disaccharides / polysaccharides

Answer 17

monosaccharides joined together

Question 18

disaccharides

Answer 18

dimer (joined in condensation reaction)

Question 19

polysaccharides

Answer 19

polymer joining 1000’s of monosaccharides together

Question 20

monosaccharide examples

Answer 20

glucose, galactose, fructose

Question 21

glucose, galactose, fructose

Answer 21

all have 6 carbons and same formula C6H12O6 (sugar isomers)

Question 22

alpha glucose chemical formula

Answer 22

C6H12O6

Question 23

alpha glucose

Answer 23

c1 OH group is at the bottom exact same as the OH group for c4

Question 24

beta glucose

Answer 24

c1 OH group is at the top different as the OH position of c4

Question 25

isomers meaning

Answer 25

same formula but different structure

Question 26

glucose + glucose

Answer 26

maltose (alpha c 1-4)

Question 27

glucose + galactose

Answer 27

lactose (alpha c 1-4)

Question 28

glucose + fructose

Answer 28

sucrose (alpha c 1-2)

Question 29

what breaks in a hydrolysis reaction

Answer 29

the glycosidic bond

Question 30

2 types of starch

Answer 30

amylose and amylopectin

Question 31

amylose

Answer 31

c 1-4 glycosidic bonds -> chains of alpha glucose -> coil into helix -> compact -> good for storage

Question 32

amylopectin

Answer 32

branched chain of alpha glucose molecules, c 1-4 and c 1-6 glycosidic bonds

Question 33

3 factors of amylopectin

Answer 33

Large SA Insoluble Large cell

Question 34

How does a large SA affect amylopectin

Answer 34

rapid hydrolysis by enzymes to release glucose for respiration

Question 35

How does being insoluble affect amylopectin

Answer 35

Doesn't affect water potential (osmosis)

Question 36

How does a large cell affect amylopectin

Answer 36

Doesnt diffuse out of cells

Question 37

glycogen

Answer 37

- only animal cells (stored in muscles + liver) - c 1-4 and c 1-6 glycosidic bonds used

Question 38

3 factors of glycogen

Answer 38

shorter chains insoluble large

Question 39

how does having shorter chains affect glycogen

Answer 39

glycogen more rapidly hydrolysed into glucose used in respiration -> required by animals (move more)

Question 40

how does being insoluble affect glycogen

Answer 40

doesnt affect water potential

Question 41

how does being large affect glycogen

Answer 41

doesnt move out of cells

Question 42

cellulose

Answer 42

- condensed beta glucose molecules - c 1-4 beta glycosidic bonds

Question 43

factor of cellulose

Answer 43

long straight unbranched chains

Question 44

how does having long straight unbranched chains affect cellulose

Answer 44

long straight unbranched chains of beta glucose -> (Joined by) many weak hydrogen bonds -> form microfibrils / macrofibrils -> provide rigidity / strength / support to plant cell walls

Question 45

benedicts test for reducing sugar

Answer 45

- add 2cm3 benedicts solution to the sample - heat to 95C - positive brick-red / red /orange / yellow / green precipitate - negative blue / light blue

Question 46

benedicts test for non reducing sugar

Answer 46

no change in benedicts test for reducing sugar - heat sample with acid (HCl) for a few mins to hydrolyse the glycosidic bonds then neutralise the solution with an alkali (NaHCO3) - heat again with benedicts reagent - positive brick-red precipitate

Question 47

standardising the method

Answer 47

- samples should always be shaken before testing - zero the colorimeter before use (with a control) - use the same (absorbance / transmission) filter throughout - use the same volume for each reading

Question 48

what is an arbitrary unit

Answer 48

relative unit of measurement

Question 49

test for starch

Answer 49

- add 2 drops of potassium-iodide (KI) solution to your sample / solution - positive a blue / black colour