biological molecules

Question 1

what are monomers

Answer 1

smaller units from which larger molecules are made

Question 2

what are polymers

Answer 2

molecules made from a large number of monomers joined together

Question 3

name 3 monomers

Answer 3

nucleotides
amino acids
monosaccharides

Question 4

what is a condensation reaction

Answer 4

A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

Question 5

what is a hydrolysis reaction

Answer 5

A hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule.

Question 6

what are monosaccharides

Answer 6

the monomers from which larger carbohydrates are made.

Question 7

give 3 examples of monosaccharides

Answer 7

Glucose, galactose and fructose

Question 8

how is a glycosidic bond formed

Answer 8

by a condensation reaction between two monosaccharides

Question 9

how is maltase formed

Answer 9

condensation reaction of two alpha glucose molecules

Question 10

how is sucrose formed

Answer 10

condensation reaction between glucose and fructose

Question 11

how is lactose formed

Answer 11

condensation reaction between glucose and galactose molecule

Question 12

how is glycogen and starch formed

Answer 12

condensation of alpha glucose

Question 13

how is cellulose formed

Answer 13

condensation of beta glucose

Question 14

what is the structure of glycogen

Answer 14

very highly branched using 1-4 and 1-6 glycosidic bonds
insoluble so it doesn’t affect water potential of cell
compact so much glucose stored in small space
alpha glucose so its used in respiration
very highly branched so many ends which allows for fast hydrolysis of glucose

Question 15

what is the structure of cellulose

Answer 15

made of beta glucose
alternate beta glucose monomers are at 180 degrees to each other so it forms a straight chain molecule
use 1-4 glycosidic bonds
cellulose molecules line up next to each other and forms H bonds between the cellulose molecules to form microfibrils
individually H bonds are weak but many provide strength

Question 16

what is starch made of

Answer 16

amylose and amylopectin

Question 17

what is the structure of amylose

Answer 17

helix of alpha glucose monomers, stabilised by H bonds within the molecule
unbranched polysaccharide of alpha glucose
contains 1-4 glycosidic bonds
insoluble so it doesnt affect the water potential of the cell
compact so lots of glucose stored in a small space
made of alpha glucose which is used in respiration

Question 18

what is the structure of amylopectin

Answer 18

branched molecule
contains 1-4 and 1-6 glycosidic bonds
insoluble so it doesnt affect the water potential of the cell
compact so much glucose stored in a small space
alpha glucose which is used in respiration
branched so more ends can be hydrolysed faster

Question 19

describe how you would test for the presence of starch in a sample

Answer 19

add iodine solution to sample, if starch is present solution turns from brown to blue-black

Question 20

describe how you would test for the presence of a reducing sugar in a sample

Answer 20

add Benedict’s solution to sample
boil test tube in a hot water bath
if reducing sugar is present, a brick red precipitate forms. If not, the solution remains blue.

Question 21

name two groups of lipids

Answer 21

triglycerides and phospholipids

Question 22

how are triglycerides formed

Answer 22

Triglycerides are formed by the condensation of one molecule of glycerol and three molecules of fatty acid.

Question 23

how is an Esther bond formed

Answer 23

A condensation reaction between glycerol and a fatty acid (RCOOH) forms an ester bond.

Question 24

what is the difference between triglycerides and phospholipids

Answer 24

In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate-containing group.

Question 25

what is the main function of triglycerides

Answer 25

energy storage molecules

Question 26

how does the structure of triglycerides relate to their function

Answer 26

hydrocarbon tails of fatty acids mean bonds release lots of energy insoluble in water means doesnt affect water potential of cell and forms droplets and separates layer of water

Question 27

describe phospholipid bilayer

Answer 27

hydrophilic heads facing the outside, as they are attracted by water and hydrophobic tails on inside as they are repelled by water

Question 28

describe test for lipids

Answer 28

add ethanol to sample, shake to mix and then add the mixture to a test tube of water. If lipids are present, a milky white emulsion will form and if no lipids present, the solution remains clear.

Question 29

what does a condensation reaction between two amino acids form

Answer 29

a peptide bond

Question 30

what is the primary structure

Answer 30

order of amino acids, which determines the shape of the protein

Question 31

what is the secondary structure

Answer 31

alpha helices and beta pleated sheets, with hydrogen bonds that stabilise the structure

Question 32

what is tertiary structure

Answer 32

further folding of polypeptide chain which forms 3D structure of protein and stabilised by bonds between R groups such as: H bonds, disulphide bonds, ionic bonds and hydrophobic and hydrophilic interactions

Question 33

what is the quartenary structure

Answer 33

more than one polypeptide chain makes a protein eg haemoglobin

Question 34

what is the role of sodium and potassium ions

Answer 34

co transport of glucose and amino acids, nerve impulses and muscle contractions

Question 35

what is the role of magnesium ions

Answer 35

used to make chlorophyll

Question 36

what is the role of iron ions

Answer 36

in harm prosthetic group of haemoglobin in red blood cell

Question 37

what is the role of calcium ions

Answer 37

synapse functions, insulin release and enzyme cofactor

Question 38

what is the role of hydrogen and hydroxide ions

Answer 38

involved in pH: increase Hydrogen ions conc means lower pH and increase hydroxide ions conc means higher pH

Question 39

and is the role of hydrogen carbonate ions

Answer 39

CO2 transport in blood and pH control of blood

Question 40

what are the 5 properties of water

Answer 40

metabolite, high latent heat of vaporisation, polar solvent, cohesion and high specific heat capacity

Question 41

what is the effect of water being a polar solvent

Answer 41

metabolic reactions can occur because water is polar meaning it can dissolve any substance which is charged or slightly charged, making them available to take part in metabolic reactions

Question 42

what is the effect of cohesion

Answer 42

enables transport of substances and creates surface tension transport of substances-water forms a continuous liquid column which doesnt break surface tension- intermolecular H bonds greater than the attraction between surface water molecules

Question 43

what is the effect of high specific heat capacity

Answer 43

water acts as a temperature buffer and is therefore a suitable habitat because a lot of energy is required to increase/decrease the temperature of a volume of water which means temp remains stable- important for sea life and in humans temp in organisms is easily regulated

Question 44

what is the effect of high latent heat of vaporisation

Answer 44

water is a coolant- it takes a lot of energy to evaporate water which makes water evaporation a very efficient way for organisms to lose heat energy

Question 45

what is the effect of water being a metabolite

Answer 45

water involved in crucial biological reactions eg hydrolysis- splitting using water and condensation- forming a water molecule and making water

Question 46

what is the role of phosphate ions

Answer 46

phospholipids