Aqa A Level Biology Nucleic Acids

Front 1

what are enzymes

Back 1

biological catalysts that speed up chemical reactions

Front 2

why are enzymes useful in small amounts

Back 2

reused repeatedly and are therefore effective in small amounts

Front 3

what is activation energy

Back 3

in an chemical reaction a certain amount of energy needs to be supplied to chemicals before the reaction will start

Front 4

describe 2 ways enzymes work

Back 4

2 substrates molecules need to be joined being attached tot he enzyme holds them close together- reducing repulsion

enzyme is cataylisng a breakdown reaction fitting into active site puts strain on bonds in substrate

Front 5

what is the active site

Back 5

a specific region of enzyme is functional

Front 6

what is the substrate

Back 6

moleuclue on which the enzyme acts is called the substrate this fits into the active site and forms an enzyme-substrate complex

Front 7

describe the induced fit model

Back 7

the active site is able to change shape so the substrate molecule can fit in

Front 8

describe the lock and key model

Back 8

the active site is rigid and cannot change shape so the substrate needs to be complementary

Front 9

describe to 2 ways to measure enzyme activity

Back 9

how fast the product is made-measure the amount of end product present at different times during the reaction rate can be calculated

how fast the substrate is broken down- measure amount of substance molecules left at different times during the experiment the reaction rate can be calculating

Front 10

describe the effect of temperature on enzymes

Back 10

low temp-substrates fits into active site

high temp-enzymes vibrates more this breaks some of bonds that hold it in shape

higher temp-active site changes shape and substrate can no longer fit cause it's denatures

Front 11

describe the effect of pH on enzymes

Back 11

above and below the optimum H+ and OH- ions found in acids and alkails can disrupt the ionic bonds and hydrogen bonds that hold the enzyme's tertiary structure in place and enzymes becomes denatures

Front 12

describes effect of substrates concentration on enzymes

Back 12

low substrate concentration-not all active sites are occupies

saturation point - all active site are occupied

beyond the saturation point- all active sites are occupied and there are space substrate molecules

Front 13

describe competitive inhibitor and factors

Back 13

have similar shape to the substrate

they compete with substrate for available active site

if substrate concentration is increased the effect of the inhibitor is reduced

they are not permanently bound to active site and when it leaves another molecule can take its place

Front 14

describe non-competitive inhibitors

Back 14

they attach themselves to the enzyme at a binding site and changes shape of active site so the enzyme can't function so increasing substrate concentration makes no difference

Front 15

function of DNA

Back 15

it's used to store your genetic information

Front 16

function of RNA

Back 16

transfer genetic information from DNA to ribsomoes

Front 17

what is a nucleotide and what does it look like

Back 17

it is a type of biological moleclue

Front 18

how is phosphodiester bond formed

Back 18

group of 1 nucleotide and sugar of another nuceltoide are joined together

Front 19

what is a sugar phosphate backbone

Back 19

chain of phosphates and sugars

Front 20

describe DNA strucutre

Back 20

double helix structure

strands are polynucleotide

really long and coiled up very tightly and a lot of genetic information can fit into small space

2 DNA polynucleotides strands join together by H-bonds between the bases

adenine-thymine (2 H bonds)

guanine -cytosine (3 H bonds)

2 polynucleotides strands are antiparallel and run opposite directions

Front 21

describe DNA adaptions

Back 21

large molecule and carries lots of genetic information

base paring leads to DNA being able to replicate and transfer information as mRNA

very stable structure which normally passes from generation to generation without change

2 separate strands are joined only with H-bonds which allow them to separate during DNA replication and protein synthesis

Front 22

describe structure of RNA

Back 22

single, short single strand

pentose sugar is ribose

adenine uracil guanine cytosine

Front 23

describe DNA replication

Back 23

1.DNA helicase breaks hydrogen bonds between bases on 2 polynucleotide DNA strands. This makes helix unwind to 2 single strands

2. each original single acts as a template for a new strand free-floating DNA nucleotides are attracted to their complementary exposed bases on each original template strand

3.condensation reactions joins the nucleotides of new strand together by DNA polymearse hydrogen bongs between the bases on the original and new strands

4. each new DNA molecule contain one strand from original DNA molecule and 1 new strand this is the semi-conservative method

Front 24

describe the conservative model

Back 24

The complete parent DNA molecule acts as a template for the new daughter molecule, which is assembled from new nucleotides. The parent molecule is unchanged.

Front 25

describe the semi-conservative model

Back 25

The parent DNA molecule separates into its two component strands, each of which acts as a template for the formation of a new complementary strand. The two daughter molecules therefore contain half the parent DNA and half new DNA (semi-conservative hypothesis).

Front 26

what is the function of ATP and what does it look like

Back 26

stores energy

Front 27

hydrolysis reaction of ATP

Back 27

ATPaseENERGY is used

ATP +H20= ADP +Pi

Front 28

condensation reaction of ATP

Back 28

ATP synthase is used

ADP +Pi= ATP + H2O

Front 29

describe the role of ATP

Back 29

releases less energy than glucose molecule

energy released quickly

ATP can't be stored and has to be continuously made within the mitochondria of cells

Front 30

what is ATP is used for

Back 30

metabolic processes- build up macromolecules from thier basic units

movement- provide energy for muscle contraction

active transport-change shape of carrier protiens inplasma memebrane

secretion-form lysosmoes

activation of molecules-

Front 31

describe the dipolar water molecule

Back 31

water molecule has both + and - poles so it's bipolar

Front 32

describe the hydrogen bonds in water

Back 32

+ pole of 1 water molecule will be attracted to - pole pf another water molecule

so the attraction between the opposite poles is called hydrogen bonding

Front 33

describe the specific heat capacity of water

Back 33

water molecules stick together t takes more energy to separate them due to hydrogen bond

water acts as a buffer against temperature change so this is helpful in aquatic environment

Front 34

describe the latent of vaporisation of water

Back 34

hydrogen bonding between water molecules this means that it requires a lot of energy to evaporate 1g of water

Front 35

describe the cohesion and surface tension in water

Back 35

molecules sticking together due the hydrogen bonding this is cohesion so water can be pulled up the xylem tube

surface tension means the water surface acts like skin so some insects can walk on water

Front 36

describe metabolism in water

Back 36

it is used to break down many complex molecules by hydrolysis or used for condensation reaction

chemical reaction take place in aqueous medium and water is a major raw material in photosynthesis

Front 37

describe water a solvent

Back 37

water dissolves in gases, wastes, inorganic ions, small hydrophilic molecules and enzymes

Front 38

describe other important features of water

Back 38

evaporation cools organism

not easily compressed and provides support

transparent so aquatic plants can photosynthesis and light rays can penetrate jelly-like fluid that fills the eye and so reach the retina

Front 39

describe the role of iron ions

Back 39

haemoglobin is a large prtien that carries oxygen

it's made up of 4 different polypeptide chains each with an iron ion Fe2+ in the centre so when oxygen is bound it becomes Fe3+ until oxygen is released

Front 40

describe the role of hydrogen ions

Back 40

more H+ present lower the pH enzyme-controlled reactions are all affected by pH

Front 41

describe the role of sodium ions

Back 41

acts as a co-transport for glucose or amino acid can be transported into a cell

Front 42

describe the role of phosphate ions

Back 42

phosphate ion is attached to another molecule. bonds between phosphate groups that store energy in ATP. Phosphate groups in DNA and RNA allow nuclotides to join up to form the polynucleotides.