Biology-Biological molecules

Glycogen: monomer, function, structure, link

>monomer-alpha glucose forming 1-4 and 1-6 glycosidic bonds when undergo condensation reaction

>function-store of glucose in animals(muscle and liver cells)

>structure- highly branched

>link-branched structure increase SA for rapid hydrolysis back to glucose, also insoluble so doesn't affect water potential.

starch: monomer, function, structure, link

>monomer-alpha glucose undergoes condensation reaction to form 1-4 glycosidic bonds in amylase and 1-4, 1-6 bonds in amylopectin

>function-store of glucose in plants

>structure-made of 2 polymers amylose(unbranched helix) and amylopectin(branched molecule)

>link-helix can compact to store a lot of glucose in a small space, branches increase SA for rapid hydrolysis back to glucose, insoluble so doesn't affect water potential

cellulose: monomer, function, structure, link

>monomer- b-glucose and forms 1-4 glycosidic bonds when undergoes condensation reaction.

>function-provide structural strength for cell wall in plants

>structure-polymer forms long straight chains which are held parallel by hydrogen bonds to form fibrils

>link-many H-bonds provide collective strength and insoluble to doesn't affect water potential.

Induced fit model

>enzyme active site not fully complimentary to substrate

>active site moulds around the substrate

>when enzyme substrate complex formed due to moulding it puts strain on the bonds and lowers Ea.

>products are then removed and enzyme returns to its original shape.

how does temperature affect enzyme activity

>if temp too low there is not enough kinetic energy for successful collision between the substrate and the enzyme.

>if temp too high enzyme denatures, active site changes shape as tertiary structure bonds break therefore enzyme-substrate complex can't form.

how does pH affect enzyme activity

>too high or too low ph interferes with the charges of the amino acid in the active site

>this can break bonds holding the tertiary structure in place causing the active site to change

>enzyme denatures so fewer enzyme substrate complexes are formed

how does substrate and enzyme concentration affect enzyme activity

>if there is insufficient substrate the reaction will be slower as there will be fewer collision between enzyme and substrate so less enzyme-substrate complexes formed

>if there are insufficient enzymes then the enzyme active site becomes saturated with the substrate and is unable to work any faster

how do polynucleotides form

>created via condensation reaction between the deoxyribose sugar and the phosphate group

>this creates a phosphodiester bond

>these are very strong covalent bonds ensuring the genetic code doesn't break down.

primary structure of a protein

>order of amino acids in a polypeptide chain

>if an amino acid is changed it could cause the bonds to form in different places changing the 3D shape.

>therefore enzymes would have a different active site so they can't form enzyme substrate complexes and will be non-functioning.

secondary structure of a protein

>sequence of amino acids causes parts of a protein molecule to bend into an a-helix or folded beta pleated sheets.

>hydrogen bonds hold the secondary structure in place

tertiary structure of a protein

>further folding of the secondary structure

>to form a unique 3D shape

>held in place by ionic, hydrogen and disulphide bonds

>ionic and disulphide bonds form between R groups of different amino acids

quaternary structure of a protein

>a protein made up of more than one polypeptide chain.

properties of water: strong cohesion

>enables effective transport in tubes

>strong cohesion provides structure for columns of water

>leads to surface tension creating a skin like barrier for small bodies to live on

properties of water: metabolite

>water is used or formed in many metabolic reactions for example condensation and hydrolysis reactions.

properties of water: high latent heat of vaporisation

>amount of energy need to change 1kg of liquid to gas

>H-bonds makes it difficult to separate water molecules so lots of energy needed for water to evaporate

>when water evaporates energy is used so it cools the environment it evaporated on

properties of water: high specific heat capacity

>means a lot of energy is required to raise the temperature of water

>happens as some of the heat energy is used to break hydrogen bonds between water molecules

>important for organisms as it means the temperature of water remains relatively stable

properties of water: good solvent

>water has the ability to dissolve many substances

>polar molecules readily dissolve in water due to the fact it is dipolar.

>slight + charge on hydrogen attracts any negative ions in solutes and slight - charge on oxygen attracts any positive ions in solutes

properties of triglycerides

>don't affect water potential as they are large and insoluble

>low mass so a lot can be stored without increasing mass or restricting movement

>large ratio of energy storing C-H bonds to C atoms so a lot of energy is stored in the molecule.

>metabolic water source due high ratio of H:O atoms so triglycerides release water when oxidised.

what is ATP and what is it made out of and its function

>ATP (adenosine triphosphate) is a nucleotide derivative.

>it is made out of a base, a ribose sugar and three phosphate groups.

>its function is as an immediate source of energy for metabolic reactions.

key properties of ATP

>only releases energy in manageable amounts so no energy wasted.

>small and soluble so easily transported around the cell.

>only one bond needs to be hydrolysed so it is an immediate source of energy.

>can transfer energy to other molecules via phosphorylation making it more reactive.

>ATP can't leave the cell meaning cell always has an immediate energy source.

process of semi-conservative replication

>DNA helicase breaks bonds between complimentary bases between the 2 strands in the double helix causing it to unwind.

>each separated strand acts as a template strand and free floating DNA nucleotides are attracted to their complimentary base pair.

>adjacent nucleotides joined together by condensation reaction to form phosphodiester bonds catalysed by DNA polymerase.

>two sets of new DNA contain one original and one newly synthesised strand.