biological molecules Flashcards
what are the three different ways that atoms can combine with each other
- covalent bonding
- ionic bonding
- hydrogen bonding
what are covalent bonds
covalent bonding is when atoms share a pair of electrons in their outer shells. As a result the outer shell of both atom is filled and a more stable compound is formed
what is ionic bonding
Ions with opposite charges attract one another. This electrostatic attraction is known as an ionic bond. Ionic bonds are weaker than covalent bonds
what is hydrogen bonding
electrons within a molecule are not evenly distributed but tend to spend more time at one position. This region is more negatively charged than the rest of the molecule.
A molecule with an uneven distribution of charge is said to be polarised - it is a polar molecule
The negative region of one polarised molecule and positively charged region of another attract each other.
Weak electrosatic bonds are formed between each other
what are macro molecules
very large molecules formed by smaller chemical structures ( e.g. monomers)
how are macro molecules formed
certain molecules (monomers) can be linked together to form long chains. These long chains are called polymers. The process they are formed is therefore called polymerisation
what are monomers usually based on
The monomers of a polymer are usually based on carbon
what polymers are industrially made
polyethene
polyester
what polymers occur naturally in living organisms
polysaccharides
polypeptides
polynucleotides
what is the basic - unit of a polysaccharide
monosaccharide or single sugar e.g. glucose
what is the basic sub unit of polynucleotides
mononucleotides
how are polypeptides formed
polypeptides are formed by linking together peptides that have amino acids as their basic sub- unit
what are condensation reactions
in the formation of polymers by polymerisation in organisms, each time a new sub unit is attached a molecule of water is formed.
Reactions that
produce produce water this way are termed condensation reactions
what is hydrolysis
if a molecule of water is produced every time a new sub unit is attached, polymers can be broken down through the addition of water.
Water molecules are used when breaking the bonds that link the sub - unit of a polymer, thereby splitting the molecule into its consituent parts.
what is metabolism
all chemical processes that take place in living organisms are collectively called the metabolism
what are carbohydrates
carbohydrates are carbon molecules (carbo) combined with water (hydrtae). Some carbohydrates molecules are small while others are large
what does the phrase “life based on carbon”
carbon atoms have an unusual feature . They can readily form bonds with other carbon atoms. This allows a sequence of carbon atoms of various lengths to be attached.
This permits a large number of different types and sizes of molecules all based on carbon.
Therefore the variety of life exists on earth are all based the versatile carbon atom
what are carbon containing molecules called
carbon containing molecules are known as organic molecules.
In living organisms, there are a relatively few other atoms that attach to carbon
this means life is therefore based on a small number of chemicals
what are monomers
Many organic molecules are made up of a chain of individual molecules. Each of the individual molecules that make up these chains is given the general name monomer
name some examples of monomers
monosaccharides
amino acids
nucleotides
name some examples of polymers
carbohydrates
protein
( these polymers are based on a surprisingly small number of atoms - carbon , hydrogen, oxygen, nitrogen|)
what is the basic monomer unit for carbohydrates
in carbohydrates, the basic monomer unit is sugar, otherwise known as a saccharide
a single monomer is a monosaccharide
a pair can combine to form a disaccharide
a large number of them chemically combined together to form polysaccharides
what are monosaccharides
monosaccharides are sweet tasting, soluble substances that have the general formula (CH2O)n where n can be any number between 3 to 7
what are some examples of monosaccharides
glucose
galactose
fructose
what is the structure of glucose
glucose is a hexose (6 - carbon) sugar
formula (C6H12O6)
atoms of carbon, hydrogen and oxygen can be arranged in many different ways
e.g.glucose has two isomers
alpha glucose and beta glucose
what are reducing sugars
reduction is a chemical reaction involving the gain of electrons or hydrogen.
A reducing sugar is therefore a sugar that can donate electrons to another chemical
(it can reduce other chemicals).
We can use this quality to identify if sugars are reducing using Benedict’s reagent
what are some examples of reducing sugars
monosaccharides and disaccharides (e.g. maltose)
are reducing sugars
how do we test for reducing sugars
we use the Benedict’s test
what chemical do we use in the Benedict’s test
Benedict’s reagent
what is Benedict’s reagent
Benedict’s reagent is an alkaline solution of copper (II) sulfate. When a reducing sugar is heated with Benedict’s reagent it forms an insoluble red percipitate of copper (I) oxide
how do we carry out the Benedict’s test
Add 2cm3 of food sample to be tested to a test tube. If the sample is not already in liquid form, grind it up in water
Add an equal volume of Benedict’s reagent to the test tube
Heat the mixture in a gently boiling tube for five minutes and wait for colour change
what is the relationship between the concentration of reducing sugar and the colour of the solution and the precipitate
blue (none)
green (very low)
yellow (low)
orange (medium)
red (high)
what are some disaccharides
-glucose joined to glucose forms maltose
glucose joined to fructose forms sucrose
glucose joined to galactose forms lactose
what happens when a monosaccharide joins together
when a monosaccharide join, a molecule of water is removed and the reaction is therefore called a condensation
The bond formed is called a glycocidic bond
what happens when water is added to a disaccharide
when water is added to a disaccharide it breaks down (under suitable conditions) releasing the consituent monosaccharides. This is called hydrolysis (addition of water that causes breakdown)
what are non reducing sugars
some disaccharides (e.g. sucrose) are known as non - reducing sugars This is because they do not change the colour of Benedict's reagent when heated with it
how do we test for non reducing sugars
To test for non reducing sugars we must hydrolyse it into its monosaccharides components by hydrolysis
If the sample is not in liquid form it must be ground up in water first
method:
Add 2cm3 of the food sample being tested to 2cm3 of Benedict’s reagent in a test tube and filter
place test tube in a gently boiling water bath for 5 mins. If the Benedict’s regent does not change colour (solution remains blue) , then a reducing sugar is not present
Add another 2cm3 of the food sample to 2cm3 of hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 mins. The dilute hydrochloric acid will hydrolyse any disaccharide present into its consituent monosaccharide
Slowly add sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid. Test with pH paper to check that the solution is alkaline
Re- test the solution by heating with 2cm3 of Benedict’s reagent in a gently boiling water bath for 5 mins
if non- reducing sugar was present in the original sample the reagent should turn orange - brown. This is due to the reducing sugars that were produced from the hydrolysis of the non - reducing sugar
what are polysaccharides
polysaccharides are polymers formed by combining together many monosaccharide molecules
what are some features of polysaccharides
very large molecules
they are insoluble molecules. This feature makes them suitable for storage
what happens when polysaccharides are hydrolysed
they are broken down into disaccharides/monosaccharides
name some polysaccharides
starch
cellulose
glycogen
what is starch and where is it stored
starch is a polysaccharide that is found in many parts of plants in the form of small grains
especially large amount occur in seed and storage organs (potato tubers)
how is starch formed
starch is formed by joining 200 and 100000 together alpha glucose molecules by glycosidic bonds in a series of condensation reaction
how do we test for starch
starch is easily detected by its ability to change colour of the iodine in potassium iodide solution from yellow to blue black
method
Place 2cm3 of the sample being tested into a test tube (or add two drops of the sample into a depression on a spotting tile)
add two drops of iodine solution and shake or stir
the presence of starch is indicated by a blue black coloration
what makes larger molecules different from one another
the various different ways they combine with the smaller molecules to form them
why is starch so important
it forms an important component of food and is the major energy source in most diets
what is the structure of starch
made up of chains of alpha glucose
the chains may be branched or unbranded
unbranded chains are wound into a tight coils that makes the molecules compact
The OH groups are pointing inwards and these form hydrogen bonds that hold the helix in place
how does the structure of starch relate to the function
insoluble
therefore water is not drawn into the cells by osmosis
large and insoluble
does not diffuse out of the cells
compact
a lot of it can be stored into a small space
when hydrolysed it forms alpha glucose which is both easily transported and readily used in respiration
branched form has many ends, each of which can be acted on by enzymes simultaneously meaning that glucose are released very rapidly (for respiration)
where is starch found
starch is never found in animal cells
so it is found in plant cells
where is glycogen found
glycogen is found in animal and bacteria cells but never plant cells
what is the structure of glycogen
the structure of glycogen is similar to starch but has many shorter chains and is highly branched
what is the function of glycogen
major carbohydrate storage of animals
the mass of carbohydrates is relatively small because fat is the main storage in animals
where is glycogen stored
in animals it is stored as small granules mainly in the muscles and liver
how does glycogen structure relate to its structure
similar to starch except it is more highly branched than starch. Therefore it has more ends that can be acted on simultaneously by enzymes. This means more rapidly hydrolysed to form glucose monomers which are used in respiration.
This is important to animals which have a higher metabolic rate and therefore respiratory rate than plants because they are more active
how is cellulose different from glycogen and starch
cellulose is made from beta glucose. This produces a fundamental difference in the structure and function of the polysaccharide
e.g. rather than forming a coiled chain like starch, cellulose has straight, unbranded chains
what is the structure of cellulose
has straight unbranded chains. These run parallel to one another, allowing hydrogen bonds to form cross linkages between adjacent chains
the OH group occur on both sides of the molecule so it can form hydrogen bonds with other chains on both sides
what do the hydrogen bonds in cellulose do
while each individual hydrogen bond adds very little to the strength of the molecule, the sheer overall number of them makes considerable contribution to strengthening cellulose
This contributes to strengthening cellulose
what is the function of cellulose
cellulose molecules group together to form microfibrils which in turn are arranged in parallel groups called fibres
cellulose is a major component of plant cell walls and provides rigidity to the plant cell.
The cellulose cell wall also prevents the cell from bursting as water enters by osmosis
how does the cell wall prevent the cell from bursting when the water enters it by osmosis
it does this by exerting an inward pressure that stops any further influx of water. As a result, living plant cells are turgid and push against one another, making woody parts of the plant semi rigid
This is especially important in maintaining stems and leaves in a turgid state so that they can provide the maximum surface area for photosynthesis
what is the relation between the structure and function of cellulose
chains run parallel with each other and are crossed linked by hydrogen bonds which add collective strength
these molecules are grouped to form fibres all of which adds more strength
what are lipids
lipids are varied group of substances that share certain characteristics
what are some characteristics that all lipids share
they contain carbon, hydrogen and oxygen
they are insoluble
They are soluble in organic solvents such as alcohols and acetone
Fats are solid at room temp (10-20 C) whereas oils are liquid
what is the main group for lipids
the main groups of lipids are triglycerides (fats and oils) and phospholipids
what are some of the roles of lipids
lipids have many roles :
IN MEMBRANES
SOURCE OF ENERGY
WATERPROOFING
INSULATION
PROTECTION
what is the lipids role in the cell membrane
IN MEMBRANES
one role of lipids is in the cell membranes (cell - surface membranes and membranes around organelles).
Phospholidpids contribute to the flexibility of membranes and the transfer lipid soluble substance across them
how are lipids a good source of energy
SOURCE OF ENERGY
when oxidised, lipids provide more than twice the energy as the same mass of carbohydrate and release valuable water
how are lipids good at waterproofing
WATERPROOFING
lipids are insoluble in water and therefore useful as a waterproofing. Both plants and insects have waxy , cuticles that conserve water, while mammals only produce oily secretion from the sebaceous glands in the skin
how are lipids good at insulation
fats are slow conductors of heat and when stored beneath the body surface help to retain body heat. They also act as electrical insulators in the myelin sheath around the nerve cells
how are lipids good for protection
fat is often stored around delicate organs, such as the kidney
what are triglycerides
triglycerides are a type of lipids
three (tri) fatty acids
combined with glycerol (glyceride)
how are triglycerides formed
in triglycerides, each fatty acids forms an ester bond with glycerol in condensation reaction. Three water molecules are produced. The fatty acids may not all be identical
(hydrolysis of this lipid produces glycerol and three fatty acids)
what makes certain triglycerides different from one another
different properties
as the glycerol molecule in all triglycerides are the same, the difference in the properties of different fats and oils come form variations in the fatty acids
how many fatty acids are there
over 70 different fatty acids
all have a carboxyl (-COOH-) group with a hydrocarbon chain attached to it
what does the terms saturated, mono unsaturated and polyunsaturated
If the hydrogen chain has no carbon- carbon bonds, the fatty acids is then described as saturated (all the carbon atoms are linked to the maximum possible number of hydrogen atoms)
a single double bond is mono- unsaturated
more than one double is present, it is polyunsaturated
how does the structure relate to the properties of triglycerides
triglycerides have a high ratio of energy storing carbon - hydrogen bonds to carbon atoms therefore they are an excellent source of energy
low mass to energy ratio, making them good storage molecules . This is especially beneficial to animals as it reduces the mass they have to carry as they move around
large, non polar molecules, triglycerides are insoluble on water. This means their storage does not affect osmosis in cells or the water potential of them
what are phospolipids
phospholipids are similar to triglycerides except that one of the fatty acid molecules is replaced by a phosphate molecule
what are the the two parts phospholipids are made up of
whereas fatty acid molecules repel water (are hydrophobic) phosphate molecules attract water (are hydrophilic)
therefore a phospholipid is made of two parts:
1. a hydrophilic head interacts with water (is attracted to it) but not with fat
2.a hydrophilic tail that orients itself away from water but mixes with fat
what are molecules that have two ends called
we say that the molecule is polar
what happens when these polar phospholipid molecules are placed in water
they position themselves so that the hydrophilic heads are close to the water as possible and the hydrophobic tails are as far from the water as possible
how does the structure of phospholipids relate to their properties
phospholipids are polar molecules . This means that in an aqueous environment, phospholipids molecules form a bilayer within cell surfaced membranes . As a result, a hydrophobic barrier is formed between the inside and outside of a cell
the hydrophilic phosphate heads of phospholipid molecules help to hold the surface of cell- surface membrane
phospholipid structure allows them to form glycolipids by combining with carbohydrates within the cell surface membrane. These glycolipids are important in cell recognition
how do we test for lipids
take a completely dry and grease free test tube
take 2cm3 of the sample being tested, add 5cm3 of ethanol
- shake the test tube thoroughly to dissolve any lipids in the sample
- Add 5cm3 of water and shake gently
- a milky - white emulsion indicates the presence of a lipid
- as a control, repeat the procedures using water instead of the sample; the final solution should remain clear
what are proteins
are large molecules that are made up of chains of polypeptides. Polypeptides basic sub unit are amino acids
what are amino acids
amino acids are the basic monomer units which combine to make up a polymer called a polypeptide. Polypeptides can combine to form proteins
how many amino acids have been identified
about 100 amino acids have been identified, of which 20 occur naturally in proteins
- the fact that the same 20 amino acids in all living organisms provides indirect evidence for evolution
what is the structure for amino acids
all of these groups are attached to a single carbon atom
amino group (-NH2) from which the amino part of the name amino acid is derived
the carboxyl group (-COOH) an acidic group which gives the amino acid the acid of its name
hydrogen atom (-H)
R (side) group - a variety of different chemical groups. Each amino acid has a different R group. These 20 naturally occurring amino acids differ only in their R (side) group
what is the primary structure of protiens
the primary structure is the sequence of amino acids found in a polypeptide chain.
This process happens through a series of condensation reactions where many amino acid monomers join together to form a polypeptide chain.
what determines the sequence of amino acids in a polypeptide chain
this sequence is determined by DNA
how many different types of primary protein structures are there
as polypeptides have many (usually hundreds) of the 20 naturally occurring amino acids joined in different sequences, it follows that there is an almost limitless number of possible combinations, and therefore types of primary protein structure
what determines the shape of the protein and its function
the primary structure of the amino acid determines the proteins ultimate shape and therefore its function
what happens if the primary structure of the protein changes
a change in just a single amino acid in the primary sequence can lead to a change in the shape of the protein and may stop it carrying out its function less well, or differently
what is the secondary structure of proteins
the secondary structure of a protein is the shape which the polypeptide chain forms as a result of hydrogen bonding. This shape is a spiral known as a helix (alpha helix)
why does the long polypeptide chain twist
The linked amino acids that make up a polypeptide possess both -NH and -C=O groups on either side of every peptide bond.
The hydrogen of the -NH group has an overall positive charge while the O of the -C=O group has an overall negative charge. These two groups therefore readily form weak bonds called hydrogen bonds. This causes the long polypeptide chain to be twisted into a 3-D shape - alpha helix.
what is the tertiary structure of a protein
the tertiary structure of a protein is the bending and twisting of the polypeptide helix into a compact
structure
The alpha-helices of the secondary protein structure can be twisted and folded even more to give the complex and often specific 3-D structure of each protein. This structure is maintained by a number of different bonds.
Where these bonds occur depends on the primary structure of the protein
what are the bonds that help maintain the tertiary structure of the protein
disulfide bridges - fairly strong and are not easily broken
ionic bonds - normally forms between the carboxyl groups and amino groups that are not involved in forming peptide bonds.
Are weaker than disulfide bridges and are easily broken by changing the pH
hydrogen bonds - numerous but easily broken
why is the 3D shape of the protein important
It is the 3D shape of a protein that is important when it comes to how it functions.
It makes each protein distinctive and allows it to recognise and be recognised by other molecules.
It can then interact with these molecules in a very specific way
what is the quaternary structure of a protein
the quaternary structure is the combination of a number of different polypeptide chains and associated non - protein (prosthetic) groups into a large, complex protein e.g. haemoglobin
large proteins often form complex molecules containing a number of individual polypeptide chains that are linked in various ways. It may also contain prosthetic groups associated with the molecules e.g. iron-containing haem group in haemoglobin
what determines the 3D shape of the protein
it is the sequence of the amino acids in the primary structure that determines the 3D shape in the first place
how do peptide bonds form
through a series of condensation reactions which is essentially the removal of water.
The water is made by combining an -OH from the carboxyl group of one amino acid with an -H from the amino group of another amino acid.
The two amino acids then become linked by a new peptide bond between the carbon atom of one amino acid and the nitrogen atom of the other
how can this peptide bond be broken
the peptide group can be broken by the addition of water (hydrolysis).
The dipeptide would be broken into its two constituent amino acids
how do we test for proteins
the most reliable test for proteins is the Biuret test. The biuret test detects peptide bonds
METHOD:
1. place a sample of the solution to be tested in a test tube and add an equal volume of sodium hydroxide solution at room temperature
- add a few drops of very dilute (0.05%) copper (II) sulfate solution and mix gently
- a purple colouration indicates the presence of peptide bonds and hence a protein. If no protein is present, the solution remains blue
what are enzymes
enzymes are globular proteins that act as catalyst
They alter the rate of a chemical reaction without undergoing permanent changes themselves.
They can be reused repeatedly and are therefore effective in small amounts
how do enzymes alter the rate of a chemical reaction
enzymes lower the activation energy of an reaction .
Therefore enzymes allow the reaction to take place at a lower temperature than normal
This enables some metabolic processes to occur rapidly at the human temperature 37C which is relatively low in terms of chemical reactions
what must happen in order for a reaction to happen
for reactions to happen naturally a number of conditions must be satisfied:
- molecules must collide with sufficient energy to alter the arrangement of their atoms
- free energy of the products must be less than that of the substrates (exothermic reaction)
- many reactions require an initial amount of energy to start. This energy is the minimum amount of energy required to start the reaction (activation energy)
what is the activation energy
the activation energy is like an energy barrier, which must initially be overcome before the reaction can proceed
what would happen if our body didn’t have enzymes
without enzymes, reactions happening in our body would proceed too slowly to sustain life as we know it
what is the structure of an enzyme
enzymes being globular proteins, have a specific 3D shape that is the result of amino acids
enzymes also have a specific region known as the active site
what is the structure of the active site
the active site is made up of a relatively small number of amino acids
The active site forms a small depression within the much larger enzyme molecule
what happens at the active site
the substrate molecule neatly fits into this depression (active site) and forms an enzyme- substrate molecule ( E-S complex)
The substrate is held within the active site by the bonds temporarily formed between amino acids of the active site and groups on the substrate molecule
what is the induced fit model
induced fit model of enzyme action proposes that the active site forms as the enzyme and substrate interact ( a change in the environment of the enzyme)
In other words, the enzyme is flexible and can mould itself around the substrate in the way that a glove mould itself to the shape of the hand e.g. enzymes has general shape, like a glove, but alters in presence of the substrate
what happens as the enzyme changes shape
as it changes shape, the enzyme puts a strain on the substrate molecule.
the strain distorts a particular bond or bonds in the substrate and consequently lowers the activation energy needed to break the bond
what happens to the enzyme when the environment changes
any change in the enzyme’s environment will result to change in its shape.
The very act of colliding with its substrate is a change in its environment so its shape changes - induced fit
what is one limitation of the lock and key model
the enzyme, like a lock, is considered to be rigid structure.
This is not the case as an enzyme shape can be altered. In other words, its structure was not rigid but flexible.
Scientists therefore modified the lock and key model to the induced fit model
what must happen in order for enzymes to work
for enzymes to work it must:
- come into physical contact with its substrate
- have an active site which fits the substrate
almost all factors that influence the rate at which enzyme works do so affecting on or both of the above
how do we measure enzyme catalysed reactions
to measure the progress of an enzyme - catalysed reaction we usually measure its time - course
that is how long it takes for a particular event to run its course
The changes most frequently measured are:
-formation of the products of the reaction
-disappearance of the substrate
describe the shape of a graph that follows the formation of a products in a reaction/ disappearance of a substrate
at first there is a lot of substrate but no product
it is very easy for substrates to come into contact with empty active sites on the enzyme molecules
all enzyme active sites are filled at any given moment and the substrate is rapidly broken down into its products. The amount of substrate decreases as it is broken down, resulting in an increase in the amount of product
as the reaction proceeds, there is less and less substrate and more product
It becomes more difficult for the substrate to come into contact with the enzyme molecules because there are fewer substrate molecules and also the product molecules may “ get in the way” of substrate molecules and prevent them reaching and active site
Therefore it takes longer for the substrate molecule to be broken down by the enzyme and so it’s rate of disappearance slows down and consequently the rate of the formation of products slows down also slows
rate of reaction continues to slow until there is so little substrate that any further decrease in its concentration cannot be measured
the graph flattens out because the substrate has been used up and so little substrate that any further decrease in its concentration cannot be measured
OR
the graph flattens out because all the substrate has been used up and so no product can product can be produced
what is the effect of temperature on enzyme action
the rise in temp increases kinetic energy of molecules
As a result of, the molecules move around more rapidly and collide with each other more often
In enzyme catalysed reactions, this means that the enzyme and substrate molecules come together more often in a given time
how would the effect of temperature look like on a graph
on a graph, the effect of temperature gives a rising curve
what happens to the enzymes as the temperature begins to rise
on rising temperature also begins to cause the hydrogen and other binds in the enzyme molecule to break down
This results in the enzyme, including its active site changing shape
For many humans this begin to happen at temperatures around 45C
what happens when the enzyme and the active site changes shape
at first, the substrate fits less easily into this changed active site, slowing the rate of the reaction.
what does it mean when we say an enzyme has denatured
at some point, usually around 60C, the enzyme is so disrupted that it stops working altogether.
The enzyme is said to have denatured which is a permanent change and once occurred, the enzyme does not function
how would the graph look when an enzyme has denatured
their will be a falling curve on the graph
why has our body evolve to have a temperature of 37C
the optimum temperature differs from enzyme to enzyme. Our body temperature has evolved to 37C this may be related to the following:
- although higher body temperatures would increase the metabolic rate slightly, the advantages are offset by the additional energy (found) that would be needed to maintain the higher temperature
- other proteins, apart from enzymes, may denature at higher temps
- at higher temps, any further rise in the temp e.g. during illness, might denature the enzymes
why do different organisms have different body temperatures
different animals have different body temps,
e.g. 40C for birds because they have a high metabolic rate for the higher energy requirement of flight
what is the pH of a solution
the pH of a solution is a measure of its hydrogen ion
what happens to an enzyme when the pH moves away from optimum
it affects the rate of enzyme action
An increase or decrease in pH reduces the rate of enzyme action
If the pH is more extreme, then beyond a certain pH,, the enzyme becomes denatured
how does the pH affect enzymes
a change in pH alters the charges on the amino acids that make up the active site of an enzyme.
This causes the substrate to no longer become attached to the active site and the enzyme - substrate complex cannot be formed
- depending on how significant the change in pH is, it may cause the bonds maintaining the enzymes tertiary structure to break causing the active site to change shape
what determines the arrangement of the active site
the arrangement of the active site is partly determined by the hydrogen and ionic bonds between -NH2 and COOH groups of the polypeptide that make up the enzyme
The H+ ions ( from the changing of the pH) affects this bonding, causing the active site to change shape
what happens to a reaction when there is a low enzyme concentration
there are too few enzyme molecules to allow substrate molecules to find an empty active site. The rate of the reaction is therefore only half the maximum possible for the number of substrate molecules available
what happens to a reaction when there is an intermediate enzyme concentration
with twice as many enzyme molecules available, all the substrate molecules can occupy an active site at the same time .
The rate of reaction has doubles to it’s maximum because all active sites are filled
what happens to the reaction when there is a high enzyme concentration
the addition of further enzyme molecules has no effect as there are already enough active sites to accommodate all the available substrate molecules
There is no increase in the rate of reaction
