Biological molecules

Question 1

specific heat capacity

Answer 1

amount of energy needed to heat 1kg of a substance by 1 degree Celsius

Question 2

water

Answer 2

is polar, electron spends more time around the O - making it negative, and H positive, water molecules bond together via hydrogen bonds

Question 3

latent heat of vaporisation

Answer 3

the amount of energy required to change the physical state of a substance

Question 4

solvent

Answer 4

liquid substance which can dissolve a wide range of molecules

Question 5

adhesion

Answer 5

the tendency of molecules to be attracted to other molecules of a different type

Question 6

cohesion

Answer 6

the tendency of molecules of a substance to attract one another

Question 7

which elements make up alpha-glucose?

Answer 7

carbon, oxygen and hydrogen

Question 8

monomers

Answer 8

can be defined as molecules that can be joined together with additional identical molecules to make larger molecules called polymers. monomers are a single molecule of them

Question 9

carbohydrates general formula?

Answer 9

CnH2nOn

Question 10

monosaccharides

Answer 10

single sugars, classified according to the number of carbon atoms they contain, 3 carbon sugars - trioses, 5 carbon sugars - pentoses, 6 carbon sugars - hexoses

Question 11

polymers

Answer 11

comprised of repeating units of monomers

Question 12

what is the process called of joining molecules together?

Answer 12

polymerisation

Question 13

what is a condensation reaction?

Answer 13

the removal of a H2O

Question 14

what is a hydrolysis reaction?

Answer 14

addition of water to break bonds

Question 15

two examples of pentose sugars?

Answer 15

ribose and deoxyribose, found in RNA and DNA

Question 16

how do glucose give you energy?

Answer 16

has many C-H bonds, which can be broken to release energy during respiration to make ATP

Question 17

disaccharides

Answer 17

formed when two monosaccharides are joined together in a condensation reaction, the bond formed between the two are known as glycosidic bonds, function as energy sources, soluble and easily transported

Question 18

reducing sugars

Answer 18

all monosaccharides and some disaccharides are known as reducing sugars, reducing sugars will reduce Benedict’s reagent from blue to an orange red in colour

Question 19

starch

Answer 19

mixture of two polymers of alpha glucose, one of the polymers is amylose joined by 1,4 glycosidic bonds and will cause them to have a helical shape, helical shape is compact and makes it a good molecule for energy storage, amylopectin is the other polymer and is branched

Question 20

glycogen

Answer 20

structurally similar to amylopectin but has many more branches and the branches are shorter, the increased number of branches allows faster hydrolysis of glucose

Question 21

cellulose

Answer 21

main structural polysaccharide found in plant cell walls, it is an unbranched polymer of thousands of beta glucose molecules, it is a straight chain

Question 22

lipids

Answer 22

they are marcomolecules, do not contain repeating units or monomers, contains the elements: C,H and O but in different proportions to carbohydrates

Question 23

triglycerides

Answer 23

they are not monomers or polymers, composed of three fatty acids joined to a glycerol molecule, reserves energy, insulation, mechanical protection, metabolic water, if all or most are saturated then a saturated fat is formed, types of fatty acids effects it’s chemical and physical properties, tend to be solid at room temperature, fats are most often found as energy stores in animals, molecule is insoluble, if all or most are unsaturated then an oil is formed, oil is found in plants as energy stores in seeds

Question 24

phospholipids

Answer 24

hydrophilic phosphate head and hydrophobic fatty acid tails, one fatty acid can be replaced by a polar phosphate group

Question 25

cholesterol

Answer 25

cholesterol molecules located between the tails of the phospholipid molecules where they serve to stabilise the membrane, classed as lipids although they belong to different subgroup - steroids

Question 26

amino acids

Answer 26

20 different amino acids polymerised into proteins, all amino acids have same general structure, the only difference is the R group, in an amino acid there is 3 groups: amino group, R group and carboxyl group, amino acids bond together by a condensation reaction with water being lost and the bond formed is called a peptide bond

Question 27

polypeptide

Answer 27

can contain any number if each of the 20 amino acids

Question 28

primary structure in proteins

Answer 28

describes type, number and sequence in which amino acids are joined together, this structure forms the polypeptide backbone

Question 29

secondary structure in proteins

Answer 29

the way the polypeptide chain/backbone is coiled or folded, either it is coiled like a spring to form an alpha helix or can line up side by side to produce a beta-pleated sheet, secondary structure held together by hydrogen bonds

Question 30

tertiary structure in proteins

Answer 30

produced when the secondary structure is further folded and coiled, maintained by disulphide bridges, ionic bonds, hydrophobic interactions, hydrogen bonds

Question 31

quaternary structure in proteins

Answer 31

if a protein is made up of more than one polypeptide chain then it has quaternary structure, these are globular proteins that contain a non-protein component called the prosthetic group, for example haemoglobin

Question 32

globular proteins

Answer 32

very diverse in structure, well developed tertiary or quaternary structure, soluble in water, tertiary structure critical to function, polypeptide chains are folded into a spherical shape, amino acid sequence is varied, catalytic - enzymes, regulatory - hormones, transport - haemoglobin, protective - antibodies

Question 33

conjugated protein

Answer 33

a globular protein with a prosthetic group

Question 34

fibrous proteins

Answer 34

proteins in which secondary structure dominates, form long shapes and are only found in animals, insoluble in water, very tough physically, may be stretchy, parallel polypeptide chains in long fibres or sheets, amino acid sequence not varied, structural role in cells and organisms - for example collagen or keratin, contractile - for example myosin or actin

Question 35

name given to positive ion?

Answer 35

cation

Question 36

name given to negative ion?

Answer 36

anion

Question 37

meaning of the word organic?

Answer 37

contains carbon, hydrogen and oxygen

Question 38

biuret test

Answer 38

tests for proteins, adding sodium hydroxide and copper sulphate to a food sample, if protein present the biuret reagent changes colour from blue to purple

Question 39

iodine test

Answer 39

tests for starch, iodine solution added to sample, if starch present colour changes from orange/brown to blue-black

Question 40

emulsion test

Answer 40

tests for lipids, add ethanol to sample and shake for 60 seconds, put solution into water, if lipid present then solution goes milky colour, no lipid present the solution remains colourless

Question 41

benedict's test for reducing sugars

Answer 41

add benedict's reagent and heat in a water bath, if sample changes colour from blue to either green, yellow, orange or brick red then reducing sugar present, reducing sugars can reduce benedict's reagent if heat is added, benedict's changes colour from blue to brick red

Question 42

benedict's test for non-reducing sugars

Answer 42

if test for reducing sugars is negative then test for non-reducing sugars, heat sample with dilute hydrochloric acid- hydrolysises glycosidic bonds - and neutralise with sodium hydrogencarbonate, heat sample with benedict's solution, if sample forms either green, yellow, orange or brick red ppt then non-reducing sugar present

Question 43

calibration curve

Answer 43

series of known concentrations of a solution can be prepared and the absorbance of each on measured using colorimeter, graph can be plotted, calibration curve can be used to calculate the concentration of glucose in the unknown sample

Question 44

chromatography

Answer 44

dip a sheet of absorbent paper into a solvent, solvent will slowly rise up the paper, spot chemicals onto the paper near the bottom but above solvent level, molecules contained in the spots will be carried up the paper, carried at a speed proportional to their size and solubility

Question 45

RF value claculation

Answer 45

RF = distance moved by compound/distance moved by solvent