biological molecules

Question 1

what are monomers

Answer 1

small units which larger molecules are made of

Question 2

what are polymers

Answer 2

the molecules made of a large number of monomers joined together

Question 3

what is a condensation reaction

Answer 3

the joining of two molecules, forming a chemical bond and releasing a molecule of water

Question 4

what is a hydrolysis reaction

Answer 4

the breaking of a chemical bond between two molecules using a molecule of water

Question 5

what a monosaccharides

Answer 5

the monomer that larger carbohydrates are made from

Question 6

how are disaccharides formed

Answer 6

2 monosaccharides join in a condensation reaction, forming a glycosidic bond

Question 7

what are three common disaccharides

Answer 7

maltose -> a glucose + a glucose
lactose -> a glucose + galactose
sucrose -> a glucose + fructose

Question 8

what are the structurally different forms of glucose

Answer 8

a glucose -> hydrogen above carbon 1

b glucose -> hydrogen below carbon 1

Question 9

what is a polysaccharide

Answer 9

many monosaccharides joined in many condensation reactions

Question 10

what is starch

Answer 10

a glucose polysaccharide found in photosynthesising and storage cells in plants

contains amylose (unbranched helical chain with 1,4 glycosidic bonds)

and amylopectin (branched chain with 1,4 and 1,6 glycosidic bonds)

Question 11

what is glycogen

Answer 11

a glucose polysaccharide found in animal cells with a high metabolic rate

highly branched with 1,4 and many 1,6 bonds

Question 12

what makes a glucose polysaccharides good for energy storage

Answer 12

helical so coiled and compact

branched so glucose accessible for hydrolysis for respiration

large and insoluble so not osmotic effect and can’t cross cell membrane

Question 13

what is cellulose

Answer 13

b glucose polysaccharide that is the main component in the cell wall of plants

Question 14

what is the structure of cellulose

Answer 14

long straight chain of b glucose with 1.4 glycosidic bonds between alternating inverted molecules

hydrogen bonds form cross linkages between hydroxyl groups in parallel chains → high tensile strength

microfibrils → macro-fibrils provide rigidity

Question 15

how do you perform a quantitative glucose test

Answer 15

produce a dilution series with a range of concentrations

produce a calibration curve

perform benedicts test

use colorimeter to measure the light passing through the sample / absorbance

plot against the calibration curve to calculate concentration of glucose

Question 16

what is the biochemical test for starch

Answer 16

iodine -> yellow to blue black

Question 17

what is the biochemical test for reducing sugars

Answer 17

heat benedicts reagent and sample
if sugar present, sample will change from blue to red/orange

Question 18

what is the biochemical test for non-reducing sugars

Answer 18

reducing sugars is negative

boil sample with acid to break glycosidic bonds

neutralise with alkali

heat with benedicts reagent again

if sugar present, sample will now change from blue to red/orange

Question 19

what are the monomers of proteins

Answer 19

amino acids

Question 20

what is the structure of an amino acid

Answer 20

amine group (NH2)
carboxyl group (COOH)
r/variable group
hydrogen

Question 21

how are dipeptides formed

Answer 21

2 amino acids joined by a peptide bond between amine group and carboxyl group in a condensation reaction

Question 22

what are polypeptides

Answer 22

many amino acids joined in many condensation reactions

Question 23

what is the structure of a polypeptide

Answer 23

primary: sequence of amino acids, determined by DNA

secondary: folding of chain due to hydrogen bonds (a helix / b pleated sheet)

tertiary: folding of entire chain due to interaction with the R group which creates a specific 3D shape stabilised by hydrogen, ionic and disulphide bonds

quaternary: folding of multiple polypeptide chain to form functional proteins ie haemoglobin

Question 24

what is the biochemical test for proteins

Answer 24

add bieurets reagent to sample

colour change from blue to purple if present

Question 25

what is chromatography

Answer 25

a technique used to separate a mixture into individual components based on solubility of molecules

Question 26

what are the stationary and mobile phases of chromatography

Answer 26

stationary: paper mobile: solvent moving the molecules up the paper

Question 27

what is an Rf value

Answer 27

distance traveled by solute / distance travelled by solvent

Question 28

how are triglycerides formed

Answer 28

joined of 3 fatty acids with a molecule of glycerol with 3 ester bonds in condensation reactions releasing 3 molecules of water

Question 29

what can the fatty acids be

Answer 29

saturated: max number of hydrogen bonds unsaturated: contains at least one double carbon bond

Question 30

what is the function of triglycerides

Answer 30

energy source: high energy yield due to C-H bonds insulation: poor heat conductor protection: absorbs forces waterproof: hydrophobic so prevents water loss

Question 31

what is the structure of phospholipids

Answer 31

2 fatty acids, glycerol and a phosphate group

Question 32

what makes phospholipids both hydrophilic and hydrophobic?

Answer 32

hydrophilic head: phosphate is polar → soluble in water hydrophobic tails: fatty acid chains are non-polar → repel water

Question 33

what is the function of a phospholipid

Answer 33

component in the phospholipid bilayer of the cell membrane

Question 34

what are nucleic acids

Answer 34

many nucleotide monomers joined together by phosphodiester bonds in many condensation reactions

Question 35

what components make up DNA

Answer 35

deoxyribose pentose sugar nitrogenous base either adenine, thymine, guanine or cytosine phosphate group

Question 36

what components make up RNA

Answer 36

ribose pentose sugar nitrogenous base either adenine, uracil, cytosine or guanine phosphate group single stranded

Question 37

what are the roles of DNA and RNA hold respectively

Answer 37

DNA stores genetic information RNA transfers genetic information from DNA to ribosomes

Question 38

what is the structure of a DNA polynucleotide

Answer 38

two polypeptide strands that are anti-parallel in a double helix

Question 39

what are the features of DNA

Answer 39

strong, stable: double helix with many hydrogen bonds + phosphodiester bonds in sugar phosphate backbone complementary base pairing: identical replication when cells divide compact: coiled, double helix → can fit into nucleus precise code: controls protein synthesis

Question 40

what are the properties of water

Answer 40

solvent – many substances can dissolve in water, to be transported around the body high specific heat capacity -acts as a buffer to temperature change high latent heat of vaporisation - allows sweating to be an effective method of cooling high surface tension and cohesion - allows water to be drawn up the xylem in continuous columns metabolite - involved in many metabolic reactions, like respiration

Question 41

what does it mean that water is polar

Answer 41

electrons are shared unequally between bonds due to the covalent bonds between hydrogen and oxygen and the hydrogen bonds between water molecules

Question 42

what is ATP

Answer 42

adenosine triphosphate used to transfer energy in energy transferring processes

Question 43

what is the structure of ATP

Answer 43

phosphorylated nucleotide with ribose, adenine (nitrogenous base) and 3 phosphate groups

Question 44

describe the hydrolysis of ATP

Answer 44

hydrolysed into ADP and Pi catalysed by ATP hydrolase releasing energy for use in cellular processes

Question 45

what is the point of ATP hydrolysis

Answer 45

energy released for use in cellular processes phosphate can be used to phosphorylate other molecules (make them more reactive

Question 46

how is ATP resynthesised

Answer 46

condensation reaction between ADP + Pi, forming phosphoanhydride bonds, catalysed by ATP synthase