monomers, polymers and carbohydrates pmt flashcards

Question 1

define monomer.Give some examples

Answer 1

smaller units that join together to form larger molecules
monosaccharides(glucose, fructose,galactose)
amino acids
nucleotides

Question 2

define polymer.examples

Answer 2

polysaccharides,proteins,DNA/RNA

Question 3

What happens in a condensation reaction

Answer 3

a chemical bond forms between 2 molecules and a molecule of water is produced

Question 4

what happens in a hydrolysis reaction

Answer 4

a water molecule is used to break a chemical bond between 2 molecules

Question 5

name the 3 hexose monosaccharides

Answer 5

glucose, fructose,galactose
and they all have the molecular formula C6H1206

Question 6

Name the type of bond formed when monosaccharides react.

Answer 6

(1,4 or 1,6)glycosidic bond
2 monomers=1 chemical bond=disaccharide
multiple monomers=many chemical bonds=polysaccharide

Question 7

name 3 disaccharides and describe how they form

Answer 7

condensation reaction forms glycosidic bond between 2 monosaccharides.
maltose:glucose+glucose
sucrose:glucose+fructose
lactose=glucose+galactose
all have molecular formula C(12)H(22)0(11)

Question 8

Describe the structure and functions of starch

Answer 8

storage polymer of alpha glucose in plant cells
insoluble=no osmotic effect on cells
large=does not diffuse out of cells
made from amylose:
-1,4 glycosidic bonds
-helix with intermolecular H-Bonds=compact
-amylopectin:
-1,4 and 1,6 glycosidic bonds
brancjed=many terminal ends for hydrolysis into glucose

Question 9

describe the structure of functions of glycogen

Answer 9

main storage polymer of alpha glucose in animal cells(but also found in plant cells)
-1,4 &1,6 glycosidic bonds
-branched=many terminal ends for hydrolysis
-insoluble=no somatic effect&does not diffuse out of cells
-compact

Question 10

describe the structure and functions of cellulose

Answer 10

-polymer of beta glucose gives rigidity of plant cell walls(preventing bursting under turgor pressure, holds stem up)
-1,4 glycosidic bonds
-straight chain, unbranched molecule
-alternate glucose molecules are rotated 180 degrees
-H bond crosslinks between parallel strands form microfibrils=high tensile strength

Question 11

describe the Benedict’s tests for reducing sugars

Answer 11

1.add an equal volume of Benedict’s reagent to a sample
2.heat the mixture in an electric water bath at 100 for 5 mins
3.positive reselt; colour change from blue to orange & brick red precipitate forms

Question 12

describe the benedicts test for non reducing sugars

Answer 12

1.negative result:benedicts reagent emails blue
2.hydrolyse non reducing sugars e.g sucrose into their monomers by adding 1cm^3 of HCL. Heat in a boiling water bath for 5 mins
3.neutralise the mixture using sodium carbonate solution
4.proceed with the benedicts test as usual

Question 13

describe the test for starch

Answer 13

1.add iodine solution
2.positive result:colour change from orange to blue-black

Question 14

outline how colorimetry could be used to give qualitative results for the presence of sugars and starch

Answer 14

1.make standard solutions with known concentrations.record absorbance or % transmission values
2.plot calibration curve:absorbance or % transmission (y-axis), concentration(x-axis)
3. record absorbance or % transmission values of unknown samples. use calibration curve to read off concentration.