C1 - BIOLOGICAL MOLECULES Flashcards
monomers and polymers carbohydrates polysaccharides lipids proteins enzymes water ions
explain how biological molecules are evidence for evolution
all cells are made from bio molecules, ex - amino acids, which is indirect evidence for the theory ev
all organisms on earth have descended from one-a few common ancestors BECAUSE all organisms share some similar biochem
biochem = same nucleic acids, ex - DNA/RNA
despite sharing some same biochem, they have diversified over time due to EVOLUTION
what are monomers
small and basic units
many of them bonded form polymers
examples of monomers
amino acids
monosaccharides
nucleotides
what are polymers
large and complex molecules that are made of many (more than 2) monomers
examples of polymers
proteins
carbohydrates
nucleic acids (DNA/RNA)
monomers -> polymers
condensation reaction
loss of water molecule
creation of a chemical bond
polymers -> monomers
hydrolysis reaction
use of a water molecule to break down polymer into its constituent monomers
chemical bond is broken
what are sugars
‘carbohydrates’
sugar is the general term for monosaccharides and disaccharides
all carbohydrates are made of only C, H and O
what is the monomer of sugars/carbs
monosaccharides
examples of monosaccharides
glucose
fructose
galactose
what is glucose
monosaccharide
hexose sugar, 6 carbon atoms
2 isomers - alpha+beta glucose
what is the difference between alpha and beta glucose
the hydrogen and hydroxyl group are inverted on the carbon 1 atom of BETA glucose
what are dissacharides
molecules made of 2 monosaccharides
condensation reaction between 2 monosaccharides + the formation of a GLYCOSIDIC bond
formation involves the loss of a water molecules because it is a CONDENSATION reaction
examples of dissacharides
maltose = glucose+glucose (alpha)
sucrose = glucose+fructose
lactose = glucose+galactose
describe the benedicts test for REDUCING sugars
heat sample WITH benedicts reagent (heat by adding to a boiling water bath)
positive result = sample forms a brick red, orange, yellow or green precipitate
negative result = sample stays blue
what does a negative result on the benedicts test for REDUCING sugars mean
no reducing sugars
non reducing sugars may be present
how do you measure the concentration of reducing sugars
the higher the concentration of reducing sugar, the further the colour change AND the closer it is to brick red, the higher the conc of reducing sugar
filter the solution and weigh the precipitate
remove the precipitate and use a colorimeter to measure the absorbance of benedicts remaining
describe the benedicts test for NON REDUCING sugars
heat a new sample with HYDROCHLORIC ACID and then neutralise this with SODIUM HYDROGENCARBONATE
heat this sample WITH benedicts reagent
positive result = sample forms a brick red, orange, yellow or green precipitate
negative result = sample stays blue, no reducing or non reducing sugars present in sample
what are polysaccharides
carbohydrates (sugars)
made of more than 2 monosaccharides joined
monosaccharides -> polysaccharide via condensation reaction
polysaccharide -> monosaccharide via hydrolysis reaction
what is the chemical bond formed for polysaccharides
glycosidic
give an example of a polysaccharide and its monomers
amylose - poly
alpha glucose/ glucose molecules - mono
name the 3 main polysaccharides
starch
glycogen
cellulose
describe the function of starch
how plants store excess glucose
describe starch
alpha glucose
in PLANTS
made of amylose and amylopectin
describe amylose
long unbranched chains of alpha glucose
helical/cylindrical structure due to angles of glycosidic bonds
very compact and therefore its a good molecule for storage as you can fit a lot into a small space
describe amylopectin
long branched chains of alpha glucose
loads of side branches allow for easier access for enzymes, to hydrolyse the glycosidic bonds which would release energy
allows for a quick release of energy/glucose
name the features of starch that help its function
amylose is a cylindrical/compact molecule, which makes it good for storage as you can fit more into a small space
amylopectin is highly unbranched which allows for enzymes to have easier access to the glycosidic bonds and hydrolyse them for a QUICKER release of glucose
starch is insoluble in water, therefore water cant enter the cells via osmosis and cause them to swell
starch is a large molecule and can’t leave the cell
describe glycogen and its function
how ANIMALS store excess glucose/ acts as an energy store
alpha glucose
name the features of glycogen that help its function
extremely branched, allows for a quick release of stored glucose as enzymes have easier access to hydrolysing the glycosidic bonds
very compact molecule, so its good for storage
describe cellulose and its function
used for structural support, ex in the cell walls of plants
beta glucose
beta glucose molecules form straight cellulose chains, these are joined by (weak) hydrogen bonds which form MICROFIBRILS (strong fibres)
name the features of cellulose that help its function
cellulose is made of strong fibres/ microfibrils which provide structural support for cells, ex - in plant cell walls
describe the iodine test for STARCH and how to identify a positive and negative result
add iodine dissolved in potassium iodide to the test sample
+ result = blue black colour, starch = present in test sample
- result = browny orange colour, starch = not present in test sample
the colour change from browny orange to blue black is for a POSITIVE result only
describe lipids
fats/oils
found in all cells
they aren’t polymers as they aren’t made of monomers, they are made of LONG CHAINS OF HYDROCARBONS
ex, hormone testosterone = lipid
2 types of lipids = triglycerides and phospholipids
describe the structure of triglycerides
one molecule of glycerol and 3 fatty acids
chemical bond = ester bond
describe the structure of phospholipids
one phosphate group, one molecule of glycerol, 2 fatty acids
phosphate group = hydrophilic
chemical bond = ester bond
describe fatty acids
have long hydrocarbons tails which cause lipids to be insoluble in water BECAUSE the tails are hydrophobic
structure = RCOOH
R = variable group
COOH = carboxyl/ carboxylic acid
can be saturated or unsaturated
saturated vs unsaturated acids
saturated = no double bond between the carbon atoms
‘saturated’ with hydrogen
unsaturated = double bond/s between carbon atoms
causes the chain to kink
what are properties of triglycerides
ENERGY STORAGE
hydrocarbon tails of fatty acids contain lots of chemical energy
a large amount of energy released when broken down
because of the fatty acid tails, lipids have 2x energy per gram compared to carbohydrates
INSOLUBLE IN WATER
no effect of the water potential of the cell
if there was an effect on cell WP, then water could enter the cell via osmosis and cause the cell to swell
INSOLUBLE IN WATER
triglycerides bundle together as insoluble droplets because fatty acid tails are hydrophobic, therefore the tails face inwards to shield themselves from water
what are the properties of phospholipids
CELL MEMBRANES
form the phospholipid bilayer
function - control what enters and leaves the cell
phospholipid head = hydrophilic
phospholipid tails = hydrophobic
causes the formation of a double layer and also causes the centre of the bilayer to be hydrophobic and water soluble substances cant easily pass AND the membrane acts as a barrier
describe emulsion test and how to identify a POSITIVE and NEGATIVE result
shake the test substance with ethanol for a minute
pour into water
+ result = milky emulsion and more milky = more lipids present
- result = NO milky emulsion
what if the test sample if food for an emulsion test
dissolve the food in ethanol
name a precaution for the emulsion test
ethanol is flammable, therefore do the test away from any open flames
what are proteins
made of 1 or more polypeptide chains
what are the monomers of proteins
amino acids
what is a dipeptide
2 amino acids joined
what is a polypeptide
more than 2 amino acids joined
describe the general structure of amino acids
central carbon is attached to R, COOH and H2N
R - variable group
COOH - carboxyl group/ carboxylic acid
H2N - amino group/amine
how many total amino acids are there
total of 20 amino acids amongst all living things, differ through their R/variable group
describe the formation of dipeptides and polypeptides
for dipeptides, amino acid+amino acid = dipeptide
join together via a condensation reaction, involving the loss of a water molecule and the formation of a peptide bond
describe the condensation reaction between 2 amino acids to form a dipeptide
the hydroxide from the carboxyl group from one amino acid AND the hydrogen from the amine, is released to release a water of molecule
describe how the dipeptide would look like after a condensation reaction, showing the peptide bond
central carbon bonded to a double bond O, on top as the hydroxide from the amino acid was lost through condensation
H on top of N in the second amino acid, as one of the hydrogen atoms was lost in the condensation reaction
peptide bond represented by the line between the C double bonded to the O, from the first amino acid, to the N in the second amino acid
what are the 4 levels in the structure of protein
primary
secondary
tertiary
quaternary
describe the primary structure of a protein
the sequence/order of amino acids in the polypeptide chain
describe the secondary structure of a protein
hydrogen bonds form between the amino acids in the polypeptide chain
the PP chain either coils into an alpha helix or folds into a beta pleated sheet
describe the tertiary structure of a protein
further coiling or folding
hydrogen and ionic bonds and disulfide bridges form
final 3D structure of a protein only made of 1 PP chain
how do disulfide bridges form
when 2 molecules of the amino acid ‘cysteine’ come close together, the sulfur atom in one molecule of cysteine and the sulfur atom in the other molecule of cysteine
D bridge is between 2 sulfur atoms
SULFur = diSULFide
describe the quartnery structure of a protein
how multiple, more than 1, PP chains are assembled
held together by different bonds
final 3D structure for proteins made of more than 1 PP chain
ex, insulin, collagen and haemoglobin
describe the relationship between the shape of the protein and its function
the shape of a protein determines its function
how is the relationship between shape and function demonstrated by HAEMOGLOBIN
shape - compact + soluble
function - good for carrying oxygen around the body
how is the relationship between shape and function demonstrated by ENZYMES
shape - spherical shape as the PP chains are tightly folded + soluble
have roles in metabolism, ex - digestive enzymes break down large molecules (soluble)
some enzymes help in the synthesis of large molecules
how is the relationship between shape and function demonstrated by ANTIBODIES
shape - made of 2 light (short) and 2 heavy (long) PP chains bonded + have variable regions where the amino acid sequences vary greatly
function - found in the blood and involved in the immune response
how is the relationship between shape and function demonstrated by TRANSPORT PROTEINS
shape - contain hydrophobic and hydrophilic amino acids which causes the protein to fold up and form a channel
function - to transport molecules and ions across the membrane + found in the cell membranes
how is the relationship between shape and function demonstrated by STRUCTURAL PROTEINS
shape - long PP chains lying parallel to eachother with cross links between them + physically strong
function - ex, in collagen (protein found in connective tissue) there are 3 PP chains tightly coiled together which causes the so be strong and allows them to be great supportive tissue
describe the process of a biuret test for proteins
add a few drops of sodium hydroxide - ensures the test sample is alkaline
add copper (||) sulfate solution
how do you identify a positive result in a biuret test
if the solution turns purple
how do you identify a negative result in a biuret test
if the solution stays blue
what are enzymes
proteins
describe the function of enzymes
act as biological catalysts to speed up chemical reactions
what are the 2 levels enzymes can catalyse metabolic reactions
cellular, ex - respiration
organism as a whole - ex, digestion in mammals
how can enzymes affect structures in an organism
they are involved in the production of collaged which is an important protein in the CONNECTIVE TISSUES of animals
how can enzymes affect the functions in an organism
they are involved in redox reactions in respiration
name the 2 types of enzymes action
intracellular - within cells
extracellular - outside of cells
describe the importance of the active site in enzymes
the active site has a specific shape
substrate molecules bind to the active site of the enzyme
what level of structure in proteins causes enzymes to be highly specific
the tertiary structure
it determines the shape of the active site
what is the minimum amount of chemical energy needed to start the reaction
activation energy
how is activation energy usually provided
as heat
what do enzymes do to the activation energy and what impact does this have on the reaction
enzymes decrease the amount of activation energy needed
causes reactions to happen at a lower temperature, because activation energy is usually provided as heat, compared to without an enzyme
this speeds up the reaction
what forms when a substrate fits into the active site of an enzyme
an enzyme-substrate complex
give and explain 2 ways how the formation of an enzyme substrate complex lowers the activation energy
if 2 substrate molecules need to be joined, being attached to the enzymes holds them closer together which REDUCES any repulsion between the substrate molecules which allows them to bond more easily
if the enzyme is catalysing a breakdown reaction, then the substrate fitting into the active site puts a strain on bonds in the substrate which causes the substrate molecule to break up more easily
describe the lock and key model of enzyme action
enzyme = lock
substrate = key
substrate fits into the enzyme perfectly as their shapes are COMPLEMENTARY to each other
the substrate is able to attach to the active site of the enzyme through random successful collisions, which forms a enzyme-substrate complex
when the products are released, the active site shape goes back to how it originally was and is able to create a new enzyme substrate complex
what new evidence brought to light caused scientists to come up with a new model of enzyme action
they realised the lock and key model didnt present the full story
new evidence - showed the E-S complex changed shape slightly to complete the fit, to lock the substrate even more tightly to the enzyme
what is the name of the current enzyme action model
the ‘induced fit’ model
describe the induced fit model
the substrate and active site aren’t completely complementary, the shape of the active site slightly changes shape to be fully complementary
the formation of the E-S complex involves the enzyme moulding around the substrate which puts a strain on the bonds and lowers the activation energy
when the products are removed, the active site of the enzyme returns to its original shape and can bind to the next substrate molecule
why are enzymes very specific
their properties are related to their tertiary structure
enzymes are very specific as they will usually only catalyse one reaction, ex - maltase only breaks down maltose BECAUSE only one complementary substrate will fit into the active site
this is because each different enzyme has a different tertiary structure and therefore a different shaped active site
what would happen if the substrate shape doesn’t match the shape of the active site
an E-S complex wont be formed
the reaction wont be catalysed
what determines the active sites shape
the enzymes tertiary structure, which is determined by the enzymes primary structure
what happens if the tertiary structure of the protein is altered in any way
the shape of the active site will change, this would cause the substrate to no longer fit into active site
no E-S complex will be created and enzyme can no longer carry out its function
name factors that can alter the tertiary structure
changes in pH
changes in temperature
a mutation occurring in the gene that determines the primary structure of the protein
how does temperature affect enzyme activity
too low - not enough kinetic energy for successful collisions between the enzyme and substrate, no E-S complex formed so the reaction cant be catalysed
too high - the enzymes molecules vibrate and this vibration breaks some of the bonds that hold the enzymes in shape, the active site changes shape and no E-S complex can be created and the enzyme is DENATURED
name and describe the 2 ways enzyme activity can be measured
HOW FAST THE PRODUCT IS MADE - the product is different molecules than what the reaction starts with,
by measuring the amount of end product present at different times of the experiment the rate of reaction can be measured
HOW FAST THE SUBSTRATE IS BROKEN DOWN - to produce end products in a reaction the substrate molecules have to be used up,
measuring the amount of substrate molecules left at different times during the experiment the rate of reaction can be calculated
what does denatured mean
it no longer functions as a catalyst
it is a permanent change in most cases
not only if temp, pH is too high but also if its too low
what is the optimum pH value for human enzymes
most human enzymes work best at the pH of 7
however, the enzyme PEPSIN works best at pH 2 and is a human enzyme found in the stomach
what is the optimum temperature of enzymes in humans
around 37 degrees c
some enzymes, like those in biological washing powders can work well at 60 degrees c
what is the effect of pH being too low or too high, on enzyme activity
the H+ and OH- ions found in acids and alkalis, can disrupt the ionic and hydrogen bonds which hold the enzymes tertiary structure in place
causes the enzyme to become denatured and the active site shape to change
what is the effect of the substrate concentration being too low or too high
the higher the substrate concentration, the faster the reaction AS more substrate molecules means more successful collisions between the substrate and enzyme, therefore more active sites are occupied by substrate molecules
having a low substrate concentration means not all active sites are occupied and the rate of reaction is low
only has an effect until a ‘saturation’ point - where all the active sites are occupied
after the saturation point is reached, all the active sites are full and adding more substrate molecules makes no difference
what is the effect of enzyme concentration being too low or too high
the more enzyme molecules present in a solution, the more likely there is to be a successful collision between the E and the S and forming an E-S complex
increasing the concentration of the enzyme increases the rate of reaction
if the amount of substrate is limited, then there will be a point when there’s enough enzyme molecules to deal with all the available substrate, adding more enzyme has no effect
what is the effect of enzyme inhibitors
preventing enzyme activity
do this by binding to the enzyme they inhibit
what are the 2 types of enzyme inhibition
competitive
non-competitive
describe how competitive inhibitors decrease the rate of reaction
have a similar shape to the shape of substrate molecules
they compete with the substrate molecules to bind to the AS of the enzyme, and no reaction takes place
they block the AS, so no substrate molecules fit in
the amount of inhibition of the enzyme is dependent on what 2 factors
the relative concentration of inhibitor
the relative concentration of substrate
what is the effect of there being a high concentration of inhibitor - COMPETITIVE INHIBITOR
will occupy nearly all the AS
low amount of substrate will get to the enzyme
low rate of reaction
what is the effect of there being a high concentration of substrate - COMPETITIVE INHIBITOR
increased chance of the substrate getting to the AS, before the inhibitor BECAUSE the substrate will out-compete the inhibitor for the AS
increasing the concentration of substrate will increase the rate of reaction, to a certain point
explain the way the non-competitive inhibitors function
bind to the enzyme AWAY from its AS - binds to the allosteric AS
this causes the AS to change shape, so the substrate molecules can no longer bind to the AS
why dont non competitive inhibitors compete with the substrate molecules, to bind to the AS
because the substrate and non-competitive inhibitors are different shapes
what is the effect of increasing substrate concentration on non-competitive inhibition
no effect
enzyme activity is still inhibited, because the AS has changed shape (due to the non-competitive inhibitor binding to the allosteric site) and substrate molecules are no longer complementary and wont fit in and no E-S complexs can be formed
what is the purpose of DNA and RNA
needed for the function of living organisms
what type of biological molecule is DNA and RNA
nucleic acids
where are DNA and RNA found
all living cells
what do DNA and RNA carry
info
DNA function
DNA = deoxyribonucleic acid
used to store genetic info (all instructions needed to grow and develop from a fertilised egg -> a fully grown adult)
RNA function
RNA = ribonucleic acid
similar in structure to DNA
transfer genetic info form DNA -> ribosomes
function of ribosomes
bodys ‘protein factories’
read RNA to make polypeptides = translation
what are ribosomes made of
RNA and proteins
what is the monomer of DNA and RNA
nucleotides
what are nucleotides made of (DNA/RNA)
phosphate group
pentose sugar (sugar with 5 carbon atoms)
nitrogen containing base
how does the pentose sugar in nucleotides differ for DNA and RNA
for DNA, the pentose sugar is DEOXYRIBOSE
for RNA, the pentose sugar is RIBOSE
name the nitrogen containing bases for DNA
adenine - A
thymine - T
cytosine - C
guanine - G
name the nitrogen containing bases for RNA
adenine - A
uracil - U
cytosine - C
guanine - G
describe polynucleotide structure
many nucleotides join together to form polynucleotide strands/chains
nucleotides join via a condensation reaction
condensation reaction between PHOSPHATE GROUP of one nucleotide and the PENTOSE SUGAR of the other nucleotide
chemical bond formed = phosphodiester bond, 2 ester bonds joined to the phosphate group
loss of water molecule as it is a condensation reaction
chain of phosphates and sugars = sugar-phosphate backbone
describe the structure of DNA
double helix, DNA molecule = 2 separate strands wind around eachother to form a spiral
DNA strands = polynucleotides, = lots of polynucleotides joined up together in a long chain
very long and coiled up tightly, = lots of genetic info can fit into a small space in the cells nucleus
what is the structure of the DNA nucleotide
phosphate group
pentose sugar - deoxyribose
nitrogen containing base - A, T, C or G
A = adenine
T = thymine
C = cytosine
G = guanine
describe complementary base pairing
the 2 DNA polynucleotide strands join together by hydrogen bonds between bases
each base can only pair to their complementary base, A - T and C - G
always equal amounts of A+T and C+G in the DNA molecule
complementary base pairing = specific base pairing
how many hydrogen bonds are between adenine and thymine
2
how many hydrogen bonds are between cytosine and guanine
3
why are the 2 polynucleotide strands antiparallel
they run in opposite directions so they can twist to form a DNA double helix
describe the structure of RNA
made of RNA nucleotides, = contain RIBOSE sugar, a phosphate group and 4 diff bases (A, U, C and G)
form a polynucleotide strand with a sugar-phosphate backbone
how is the structure of RNA different to the structure of DNA
RNA nucleotides contain RIBOSE as their pentose sugar, while DNA nucleotides contain DEOXYRIBOSE as their pentose sugar
bases in RNA are A, U, C and G
bases in DNA are A, T, C and G
RNA is a SINGLE polynucleotide chain, DNA is a DOUBLE helix (2 polynucleotide chains wrapped around eachother)
RNA strands = much shorter than DNA polynucleotide strands
describe how DNA is the carrier of the genetic code
DNA was first observed in the 1800s, but the majority of scientists doubted it could carry the genetic code because of its simple chemical composition
some scientists argued that the genetic code must be carried by proteins and they had more chemical variation
1953 - experiments had shown that DNA was the carrier of the genetic code
which scientists determined the structure of DNA
watson and crick
is dna able to replicate itself
yes and it does so regularly
why does DNA replicate
replicates before cell division, mitosis, so each new cell has the full amount of DNA
what is the name of the method by which DNA replicates
semi - conservative replication
why is it called semi conservative replication and what does that mean
half the strands in the NEW DNA molecule are from the ORIGINAL DNA molecule
ensures there is GENETIC CONTINUITY between generations of cells, ex -> the cells produced by cell division inherit their genes from their parent cells
how is dna replicated
DNA helices BREAKS the hydrogen bonds between the bases on the 2 DNA strands
helix unwinds to form 2 single strands
each single strand = template for new strand
free floating DNA nucleotides are attracted to their complementary exposed bases (A-T and C-G) on the template strand via COMPLEMENTARY BASE PAIRING
condensation reactions join the nucleotides of the new strand together, catalysed by DNA POLYMERASE - HYDROGEN bonds form between the bases on the ORIGINAL and NEW DNA strands
each new DNA molecule = one strand from ORIGINAL DNA molecule + one NEW strand
describe the action of DNA polymerase
each end of DNA is slightly different in structure, one end = 3’ and the other end = 5’
3’ = 3 prime
5’ = 5 prime
during DNA replication, the active site of the enzyme DNA POLYMERASE is only complementary to the 3’ end = DNA nucleotides can only be added to the 3’ end
new strand is made in a 5’ to 3’ friction and DNA POLYMERASE moves down the strand in a 3’ to 5’ direction
describe the action of DNA polymerase in the DNA molecule during DNA replication
the strands in the double helix are anti-parallel, the DNA polymerase working on one template strand, moved in the OPPOSITE direction as the DNA polymerase working on the other template strand
which experiment validated watson and cricks theory of the structure of DNA and WHOs experiment was it
the semi-conservative method by meselson and stahl validated watson and cricks theory AND also showed how dna replication takes place
what would happen if dna was conservative, not semi conservative
the original DNA strands would stay together and the new DNA molecules would contain 2 new strands
no genetic continuity
describe meselson and stahls experiment proving DNA replication is semi-conservative
they used 2 isotopes of nitrogen, as DNA contains nitrogen (nitrogen containing bases)
2 isotopes - heavy nitrogen = 15N
light nitrogen = 14N
2 samples of bacteria were grown for many generations, one in a nutrient broth containing LIGHT nitrogen and the other was grown in a nutrient broth containing HEAVY nitrogen
as the bacteria reproduced (replicated), they took up nitrogen from the broth to make NUCLEOTIDES for the NEW DNA
nitrogen became part of the bacterias DNA
a sample of DNA was taken from each batch of bacteria and spun in a CENTRIFUGE
DNA from HEAVY nitrogen settled lower down in the centrifuge, compared to the DNA from the LIGHT nitrogen BECAUSE ITS HEAVIER
the bacteria grown in the HEAVY nitrogen was taken out and put in a broth containing only LIGHT nitrogen and was left for ONE round of DNA replication
a DNA sample was taken from this and spun in the CENTRIFUGE
if replication was conservative, the original HEAVY DNA would still be together and settle at the bottom while the new LIGHT DNA would settle at the top
if replication was semi conservative, the new bacterial DNA would contain ONE HEAVY DNA STRAND and ONE LIGHT DNA STRAND - and it would settle between where the original light and heavy DNA strands settled in the centrifuge
the DNA settled out in the middle, showing DNA molecules contained a mix of both HEAVY and LIGHT nitrogen meaning the bacterial DNA had replicated semi conservatively in the light nitrogen
what is required for all processes and what is the adaption plants and animals made
energy is required for ALL life processes
plants and animals are able to store and release energy for this, very IMPORTANT
what do plant and animal cells need for biological processes to occur
energy
why is energy important for plants
active transport - transport solutes from their leaves
DNA replication
cell division
protein synthesis
why is energy important for animals
active transport - to absorb glucose from ileum epithelium -> bloodstream
DNA replication
cell division
protein synthesis
describe the purpose of ATP
plants and animal cells release energy from glucose through respiration
a cell cant get its energy directly from glucose
in respiration, energy released from glucose is used to make ATP
describe the structure of ATP
nucleotide base ADENINE
ribose sugar (pentose sugar = 5 carbons)
3 phosphate groups
why is ATP called a ‘nucleotide derivative’
because ATP is a modified form a nucleotide
where does ATP diffuse when its made
to the part of the cell that needs energy
where is the energy stored in ATP
stored in the HIGH ENERGY BONDS between the phosphate groups
how is energy released in ATP
via hydrolysis reaction
describe how ATP is broken down for its use
when energy is needed by a cell
ATP broken down via hydrolysis reaction
ATP broken down into ADP (adenosine diphosphate) + Pi (inorganic phosphate)
phosphate bond broken and energy is released
hydrolysis reaction catalysed by enzyme ATP HYDROLASE
what are other uses of ATP when its been hydrolysed
- can be ‘coupled’ to other reactions that require energy
- allows released energy to be used directly to make the coupled reaction happen, INSTEAD of ATP being lost as heat/thermal energy
- the released inorganic phosphate can be used
- Pi can be added to another compound
- ‘phosphorlylation’
- often makes the compound more reactive
describe the resynthesis of ATP
ATP can be resynthesised in a condensation reaction between ADP and Pi
happens during respiration and photosynthesis
catalysed by ATP synthase
define ATP
ATP IS NOT ENERGY
ATP = store of energy
energy is used to make ATP
energy is released when ATP is hydrolysed to ADP and Pi
what is water essential for
life
describe the importance of water
vital to living organisms and makes up around 80% of a cells contents
metabolite in important reactions - ex, condensation and hydrolysis
solvent so some substances dissolve in it and most metabolic reactions take place in solution - ex, cytoplasm of eukaryotic and prokaryotic cells
has a high latent heat of vaporisation and high specific heat capacity - helps with temperature control
water molecules are very cohesive (stick together), helps transport in plants and transport in other organisms
describe the structure of water
shape of a water molecule is assymetrical
molecule is dipole, oxygen atom carries a small NEGATIVE charge while the hydrogen atoms carry a small POSITIVE charge
negative and positive charges balance, water overall has NO net charge, BUT water is still a polar (dipole) molecule
what does dipole mean
di = 2
pole = charge
2 different charges
H+ = slight positive charge
O = slight negative charge
name the 5 properties of water
important metabolite
good solvent
high latent heat of vaporisation
can buffer changes in temp
very cohesive
how is water an important metabolite and how this is important for organisms
most metabolic reactions involve condensation or hydrolysis
hydrolysis - requires a molecule of water to break a bond
condensation - releases a molecule of water as a new bond forms
ex, amino acids joined together to make polypeptides via CONDENSATION reaction
ex, energy from ATP is released via HYDROLYSIS reaction
describe how water is a good solvent and how this is important for organisms
a lot of important substances in biological reactions are ionic, ex - salt
ionic - made from one positive ion and one negative ion
water = polar, slightly positive charged end will be attracted to the negative ion WHILE the slightly negative charged end will be attracted to the positive ion
ions will be surrounded by water, therefore they will dissolve
living organisms can take up useful substances, like mineral ions, dissolved in water AND these dissolved substances can be transported around the organisms body
describe waters high latent heat of vaporisation and how this is important for organisms
water evaporates/vaporises when the hydrogen bonds holding water molecules together are BROKEN, this allows water molecules on the surface of water to escape into the air as a GAS
takes a LOT of energy (heat) to break the hydrogen bonds between water molecules, a lot of energy is used for water to evaporate
useful for living organisms because it means they can use water loss through evaporation to cool down, without losing too much water
when water evaporates it carries away heat energy from a surface, this means it cools the surface and helps to lower the temperature
ex- when humans sweat to cool down
describe how water can buffer/resist changes in temp and how this is important for organisms
H bonds give water a HIGH SPECIFIC HEAT CAPACITY, = energy needed to raise temp of 1 gram of substance by 1 degree c
when water is heated a lot of the heat energy is used to break the H bonds between the water molecules, = less heat energy available to increase the temp of water
it takes a lot of energy to heat up water
useful for living organisms as it means water doesn’t experience rapid temp changes, = makes water a good habitat as temp under water would be more stable than temp on land
water in organisms also remains fairly stable, = helps maintain a constant internal body temp
describe how water is very cohesive and how this is important for organisms
cohesion = attraction between molecules of the same type, ex - 2 water molecules
water molecules are very cohesive (stick together) because they are polar
strong cohesion helps to make water flow, makes it good for transporting substances - ex, how water travels in columns up the xylem in plants
strong cohesion also means water has HIGH SURFACE TENSION when it comes into contact with air
this why sweat forms droplets which evaporate from the skin to cool the organism down
reason why pond skaters and other insects can ‘walk’ on the surface of a pond
what is an ion
an atom or a group of atoms that has an electric charge
what is the name of an ion with a positive charge and what are examples
cation
sodium, Na+
calcium, Ca 2+
what is the name of an ion with a negative charge and what are examples
anion
chlorine, CL-
phosphate, PO4 3-
what is an inorganic ion
one that doesn’t contain carbon, there are some exceptions
found in the cytoplasm of cells and in the body fluids of organisms
each ion has a specific role depending on its properties
an ions role determines whether its found in high or low concentrations
what ions are in haemoglobin and what’s their role
iron ions = Fe 2+
- haemoglobin is a large protein which carries oxygen around the body, in red blood cells
- made of 4 PP chains, each chain has a iron ion in the centre
- Fe 2+ that actually binds to the oxygen in haemoglobin
- when oxygen is bound, the Fe 2+ ion temporarily becomes an Fe 3+ ion UNTIL the oxygen is released
what is the role of hydrogen ions
hydrogen ions = H+
- pH is calculated based on the concentration of hydrogen ions in the environment
- more H+ ions present = lower the pH = more acidic the environment
- enzyme controlled reactions are all affected by pH
what is the role of sodium ions
sodium ions = Na+
- a molecule of glucose or an amino acid can be transported into a cell, across cell membrane, with sodium ions
- process called co-transport
what is the role of phosphate ions
phosphate ions = PO4 3-
- when a phosphate ion is attached to another molecule, its called a phosphate GROUP
- DNA, RNA and ATP all contain phosphate groups
- the bonds between phosphate groups store energy in ATP, which is released when ATP is hydrolysed
- the phosphate groups in DNA and RNA allow nucleotides to join up to form the polynucleotides
