3.1 Biological molecules - carbs, proteins, enzymes, lipids and biochemical tests Flashcards
what are carbohydrates used by and what for
by cells for respiration and as structural components in membranes and cell walls, storage ( starch and glycogen )
what are carbohydrates used by and what for
by cells for respiration and as structural components in membranes and cell walls, storage ( starch and glycogen )
what are lipids used for?
used for respiration, the bilayer of plasma membranes, some hormones
what are proteins used for?
many cell structures, enzymes, chemical messengers, transport and components of the blood
what is water used for?
solvent found as the major component of all cells
examples of nucleic acids
DNA and RNA
what do nucleic acids do?
carry the genetic code for the production of proteins, RNA is part of ribosome structure
what are vitamins and minerals required for?
a range of enzyme functions
what is a polymer?
a long chain molecule made up of large numbers of repeating units linked together e.g. starch, proteins, DNA
what is a monomer?
one of the molecules linked together in the chain to form a polymer e.g. glucose, amino acids, nucleotides
what do 2 monomers make?
dimer
what do 3 monomers make?
trimer
glucose formula
C6H12O6
glucose + glucose
maltose + water
what is produced when 2 biological monomers are linked together
water
what is the reaction called when 2 biological monomers are linked together and water is produced
condensation reaction
what happens to the water molecule in a condensation reaction
involve the removal of a water molecule
the removal of water from monomers enables a chemical bond to form between the monomers
what happens during a hydrolysis reaction
a water molecule is added between two bonded monomers ( within a dimer or polymer ) to break the chemical bond
what is a hydrolysis reaction?
the opposite of a condensation reaction where water is split
what does a condensation reaction involve the removal of?
the removal of a water molecule
this removal of water from monomers enables a chemical bond to form between the monomers
what is a hydrolysis reaction?
the opposite of a condensation reaction
a water molecule is added between the two bonded monomers to break the chemical bond
what do carbohydrates do?
store energy and can provide structural support to plant cells
which carbohydrates are monosaccharides?
glucose
fructose
galactose
which carbohydrates are disaccharides?
maltose
sucrose
lactose
which carbohydrates are polysaccharides?
starch
glycogen
cellulose
what is the general formula for a monosaccharide?
CnH2nOn
where n = the number of carbon atoms it contains
what is the formula for glucose?
C6H12O6
what is an isomer?
compounds that have the same formula but the atoms are arranged differently
what are the structural isomers of glucose?
beta glucose and alpha glucose
what are the difference between the structures of alpha and beta glucose?
the H group and the OH group on carbon 1 swap position
where are the H group and OH group on carbon 1 on alpha glucose?
H group is above and the OH group is below carbon 1
where are the H group and OH group on carbon 1 on beta glucose?
H group is below and the OH group is above carbon 1
what is a disaccharide?
two monosaccharides bonded together by a glycosidic bond, that is formed by a condensation reaction
glucose + glucose
maltose
glucose + galactose
lactose
glucose + fructose
sucrose
how does a condensation reaction create a disaccharide?
a water molecule is removed from the OH group on carbon 1 and carbon 4 on the two monosaccharides
the bond that forms is known as a glycosidic bond
will be a 1-4 glycosidic bond if between carbon 1 and carbon 4
what reaction takes place to make a disaccharide go back to a monosaccharide?
hydrolysis reaction
what are polysaccharides?
polymers made up of many monosaccharides
how are polysaccharides created?
through condensation reactions
where is starch found?
plants
what is starch made from?
the excess glucose created during photosynthesis
what type of glucose makes up starch?
alpha glucose
what type of glycosidic bonds keep starch held together?
1,4 and 1,6 glycosidic bonds
what two polymers make up starch?
amylose and amylopectin
in starch what do the 1,4 glycosidic bonds in amylose cause?
a spiral shaped polymer
in starch what do the 1,4 and 1,6 glycosidic bonds in amylopectin cause?
result in branches
is starch soluble or insoluble?
insoluble due to the fact it is a large molecule
what is starch being insoluble an advantage?
it means it can be stored within cells and not dissolve therefore it will not change the water potential of the cell nor cause osmosis to occur
why is amylose being spiral shaped an advantage?
it can be readily compacted
why is amylopectin being branched an advantage?
it provides a larger surface area for enzymes to attach to meaning starch is readily hydrolysed back into glucose when plant cells are running low on glucose for respiration
what is glycogen?
the major carbohydrate storage molecule found in animal cells
where are the main glycogen cells stored?
in the liver and muscle cells
what is glycogen made from?
the excess glucose that has been eaten and absorbed into the bloodstream
why is glycogen mainly stored in the liver and muscle cells?
to ensure they always have access to glucose to respire and release energy
what type of glucose is glycogen made up of?
alpha glucose
why does glycogen have more of a branched structure than amylopectin?
because it contains more 1,6 glycosidic bonds
is glycogen soluble or insoluble?
its insoluble due to the fact its a large molecule
why is glycogen being insoluble an advantage?
means it can be stored within cells and not dissolve
therefore it will not change the water potential of the cell nor cause osmosis which would cause cell lysis
why is glycogen being highly branched an advantage?
means it has a larger surface areas for enzymes to attach which means it can be readily hydrolysed into glucose
glycogen is more branched than starch so it can be hydrolysed back into glucose more rapidly
why is glycogen being more branched than starch essential for animals?
because hey have a higher metabolic rate and therefore need more glucose than plants e.g. running away from a predator
what is the function of cellulose?
to provide structural strength in plants
where is cellulose located in plants and why?
in the cell wall of plants and therefore prevents cells from bursting if they take in excess water
what type of glucose is cellulose made from?
beta glucose
what glycosidic bonds is cellulose made up of?
1,4 glycosidic bonds only
why is the cellulose polymer unbranched?
because it is only made up of one type of glycosidic bond
1,4 create straight lines whereas 1,6 create branches
what is the structure of cellulose like?
the long straight chains of b glucose accumulate and lie parallel to each other
the parallel chains are then held together by many hydrogen bonds which provide strength due to the amount of them
what is the structure of cellulose called?
fibril
is cellulose soluble or insoluble?
insoluble
why is cellulose being insoluble an advantage?
it will not change the water potential of the cell and affect osmosis
how is cellulose a very strong polysaccharide?
due to the large number of hydrogen bonds in and between the fibrils
what is the method of the reducing sugars test?
- add benedicts reagent to the sample you re testing
- heat e.g. using water bath
- if a colour change of blue to yellow/ green / red is observed then it is confirmation that a reducing sugar is present
- if the solution remains blue, there is no reducing sugar present
what is an example of a non reducing sugar?
sucrose
why is sucrose not a reducing sugar?
because it cannot reduce Cu2+
how can we prove that sucrose is still a sugar but is just unable to reduce Cu2+?
the glycosidic bond must be hydrolysed to expose the reducing group
what is the method for the non - reducing sugar test?
- mix sucrose with hydrochloric acid and boil
- cool the solution and then add sodium hydroxide to make the solution alkaline
- add a few drops of benedicts reagent and heat - if a colour change of blue to yellow, green or red is observed then this is confirmation a non reducing sugar is present.
why do we mix the sucrose with the HCl and boiled in the non reducing sugars test?
this is acid hydrolysis and it breaks the glycosidic bond so that sucrose is hydrolysed back into glucose and fructose
why in the non reducing sugars test must we cool the solution and add sodium hydroxide to make it alkaline?
cooling is to prevent excessive, dangerous fizzing
the sodium hydroxide is because benedicts only works in alkaline solutions so this stage is essential
what does the rustier the red after the reducing or non reducing sugars test mean?
the higher the concentration of sugar present because more copper oxide has been made (rust)
what is the method for the test for starch?
add a few drops of iodine
it will turn blue/black if starch is present
what is the method for a test for proteins?
add biuret reagent
it will turn from blue to purple if protein is present
what is the method for a test for lipids?
your sample must first be dissolved in ethanol e.g. by shaking your sample you are testing in ethanol
once the sample is dissolved add distilled water and shake again
if lipids are present, you will observe a white emulsion
are proteins polymers or monomers?
polymers
what monomers are proteins made up of?
amino acids
what does the general structure of an amino acid include?
a central carbon
an amine group (NH2)
a hydrogen atom
a carboxyl group (COOH)
the variable group (R group)
what reaction allows amino acids to join together to make the polypeptide polymer?
Amino acids join together to make the polypeptide polymer via condensation reactions
what bonds keep amino acids together to make polypeptide polymers?
peptide bonds
what is the first structure that forms in the creation of a protein?
the polypeptide chain
what is the primary structure of a protein?
the primary structure is the sequence of amino acids in a polypeptide chain
when will the specific order of amino acids alter?
where bonds occur and how the protein folds
what does the primary structure determine overall due to the sequence of amino acids?
the primary structure determines the final 3D shape and the protein’s function
in the secondary structure of a protein what does the sequence of amino acids cause?
causes parts of a protein molecule to bend into an α helix or fold into β pleated sheets
what bonds form between the carboxyl groups of one amino acid and the amine group of another in the secondary structure?
hydrogen bonds which hold the secondary structure in place
what bonds hold the tertiary structure together?
hydrogen, ionic and disulfide bonds hold the tertiary structure
where do disulphide bonds form between in the tertiary structure of a protein?
only form between the R-groups of two amino acids that contain sulfur
describe the tertiary structure of a protein (3 marks)
- the further folding of the secondary structure
- to create a unique 3D structure
- held in place by hydrogen, ionic and disulfide bonds
what type of protein has a quaternary structure?
a protein that is made up of more than one polypeptide chain has a quaternary structure
what is a prosthetic group in the quaternary structure of a protein?
any group that is attached to a protein, but is not made up of amino acids
why is the active site specific and unique in shape?
due to the specific folding and bonding in the tertiary structure of the protein
due to this specific active site, enzymes can only attach to substrates that are complementary in shape
where are protein polymer chains, or polypeptides created?
on ribosomes in cells and are then further folded and modified in
the Golgi apparatus
what do enzymes do to the activation energy?
they can lower the activation energy needed for the reaction to occur, and therefore speed up the reaction
what is the lock and key model and what does it suggest?
this model suggests that the enzyme is like a lock and that the substrate is like a key that fits into it due to its complementary shape
the enzyme active site is a fixed shape and due to random collisions, the substrate can collide and attach to the enzyme
this forms an enzyme substrate complex.
once the enzyme-substrate complex has formed, the charged
groups within the active site are thought to distort the substrate
and therefore lower the activation energy
the products are then released, and the enzyme active site is empty
and ready to be reused
what is the induced fit model and what does it suggest?
this model suggests that the enzyme is like a glove and the substrate is like your hand; the empty glove is not exactly complementary in shape to your hand, but when your hand enters, it enables the glove to mold around your hand to become completely complementary
the enzyme active site is induced or slightly changes shape, to mould around the substrate
the formation of the enzyme substrate complex involves the enzyme moulding around the substrate, which puts a strain on the bonds and therefore lowers the activation energy
The products are then removed, and the enzyme active site returns to its original shape
what is the accepted model for how enzymes work?
the induced fit model is the accepted model for how enzymes function
what factors affect the rate of enzyme-controlled reactions?
- temperature
- pH
- substrate concentration
- enzyme concentration
- inhibitors
how does temperature the control rate of reaction?
if the temperature is too low, there is not enough kinetic energy for successful collisions between the enzyme and substrate
if the temperature is too high, enzymes denature, the active site changes shape and enzyme substrate complexes cannot form
how does pH control rate of reaction?
too high or too low a pH will interfere with the charges in the amino acids in the active site.
this can break the ionic and hydrogen bonds holding the tertiary structure in place and therefore the active site changes shape.
therefore the enzyme denatures and fewer
enzyme-substrate complexes form.
what happens to the active site when the enzymes are insufficient?
then the enzyme active sites will become saturated with substrate and unable to work any faster
what shape are competitive inhibitors?
the same shape as the substrate and can bind to the active site
what do competitive inhibitors do?
prevents the substrate from binding and the reaction occurring
if you add more substrate this will out-compete the inhibitor, knocking them out of the active site
where do non - competitive inhibitors bind to?
bind to the enzyme away from the active site (the allosteric site)
what do non - competitive inhibitors cause the active site to do?
causes the active site to permanently change shape, and therefore the substrate can no longer bind, regardless of how much substrate is added
what happens to competitive inhibitors at a high enough substrate concentration?
competitive inhibitors are knocked out of the active site and the rate of reaction will therefore return to the same as with no
inhibitor
what is the rate of reaction with a non competitive inhibitor like?
will be lower at all substrate concentrations
what structure of the proteins is an enzyme?
tertiary structure proteins
what are the two types of lipids?
triglycerides and phospholipids
how are triglycerides formed?
via condensation reactions
what are triglycerides made up of?
one molecule of glycerol and three molecules of fatty acid
what bonds are formed in triglycerides?
ester bonds are formed
what does it mean by a saturated fatty acid?
the hydrocarbon chain has only single bonds between carbons
what does it mean by an un-saturated fatty acid?
the hydrocarbon chain consists of at least one double bond between carbons
what does an R-group on a triglyceride consist of?
R-groups are fatty acids which can be saturated or unsaturated
why is a lot of energy stored in the triglyceride molecule due to its structure?
due to the large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms
why can triglycerides release water if they are oxidised due to their function?
due to the high ratio of hydrogen to oxygen atoms they act as a metabolic water source
why do triglycerides not affect water potentials and osmosis due to their structure?
they are large and hydrophobic, making them insoluble in water
why can a lot of triglycerides be stored without increasing the mass
and preventing movement due to their structure?
lipids have a relatively low mass
why do phospholipids contain?
made of a glycerol molecule
two fatty acid chains
a phosphate group (attached to the glycerol)
how do the two fatty acids also bond to the glycerol in a phospholipid?
via two condensation reactions
what bonds are in a phospholipid?
two ester bonds.
why does the hydrophilic ‘head’ of a phospholipid attract water?
it is charged
due to the phosphate being charged (polar), it repels other
fats
is the fatty acid chain on a phospholipid non-polar or polar?
non-polar
it is known as the hydrophobic ‘tail’ and it repels water but will mix with fats
why are phospholipids polar?
phospholipids have two charged regions
what does a phospholipid bilayer make up?
the plasma membrane around cells
how is the structure of a phospholipid bilayer positioned?
they are positioned so that the heads are exposed to water and
the tails are not
What reagent confirms the presence of starch?
Iodine
Iodine turns blue/black in the presence of starch and is orange/brown when starch is absent.
What color does biuret reagent turn when protein is present?
Purple
Biuret reagent is originally blue and changes to purple when it reacts with proteins.
How do you test for lipids?
Dissolve sample in ethanol, then add distilled water
A white emulsion indicates the presence of lipids.
What must be done to Benedict’s reagent for the reaction to occur?
Heated
Heating is necessary for the test to show a positive result for reducing sugars.
What is the appearance of a positive test for starch?
Blue/black color
This indicates the presence of starch when iodine is added.
What is the initial color of biuret reagent before adding protein?
Blue
The color changes to purple only when protein is present.
Fill in the blank: To test for lipids, first dissolve the sample in _______.
Ethanol
What happens after adding distilled water to the lipid solution?
Shake again to observe a white emulsion
This indicates the presence of lipids in the sample.
True or False: Acid must be boiled for the hydrolysis of non-reducing sugars.
True
What is a characteristic observation for proteins when using biuret reagent?
Purple color change
What color indicates no starch is present when using iodine?
Orange/brown
This is the color of iodine when starch is absent.
What type of sugar is sucrose classified as?
Non-reducing sugar
Sucrose cannot reduce Cu²⁺ due to its glycosidic bonds.
Why is sucrose considered a non-reducing sugar?
It cannot reduce Cu²⁺ because the chemical group needed for reduction is involved in glycosidic bonds.
Hydrolysis of glycosidic bonds is necessary to expose the reducing group.
What is the first step to test for a non-reducing sugar?
Mix sucrose with HCl and boil.
This is acid hydrolysis, which breaks the glycosidic bond.
What temperature is required for acid hydrolysis of sucrose?
Above 100 °C
Boiling is essential to provide enough energy to break the glycosidic bond.
What is done after boiling the sucrose and HCl mixture?
Cool the solution and add sodium hydroxide.
This makes the solution alkaline, which is necessary for Benedict’s reagent to function.
Why must the solution be cooled before adding sodium hydroxide?
To prevent excessive, dangerous fizzing.
This is important for safety during the test.
What reagent is added after making the solution alkaline?
Benedict’s reagent
This reagent tests for the presence of reducing sugars.
What indicates the presence of a non-reducing sugar in the test?
A color change from blue to yellow/green/red.
This indicates that reducing sugars are present after hydrolysis.
What does a rustier red precipitate in the sugar test indicate?
A higher concentration of sugar present.
More Cu²⁺ has been reduced to Cu⁺, forming copper oxide.
Fill in the blank: Sucrose is hydrolyzed back into _______ and _______ during the non-reducing sugar test.
glucose and fructose
What is a reducing sugar?
Sugars that can reduce Cu²⁺ ions in Benedict’s reagent to Cu⁺ ions, forming a brick-red precipitate
Reducing sugars include monosaccharides like glucose and some disaccharides like maltose.
What reagent is used to test for reducing sugars?
Benedict’s reagent
Benedict’s reagent is a bright blue liquid containing copper sulfate.
What color change indicates the presence of reducing sugars in a test?
Blue to yellow/green/red
A positive test result shows a gradual color change from blue to these colors depending on the concentration of reducing sugar.
What does it mean if the solution remains blue after testing for reducing sugars?
No reducing sugar is present
The absence of color change indicates a negative result.
List the biological molecules that require testing in biochemical tests.
- Reducing sugars
- Non-reducing sugars
- Starch
- Proteins
- Lipids
These tests help identify the presence of various essential biological macromolecules.
What is the first step in the procedure for testing reducing sugars?
Add Benedict’s reagent to the sample
This initiates the chemical reaction necessary for detecting reducing sugars.
What is the second step in the procedure for testing reducing sugars?
Heat the mixture
Heating is essential to facilitate the reaction between the reducing sugar and Benedict’s reagent.
True or False: Benedict’s reagent changes from blue to brick-red in the presence of reducing sugars.
True
This color change confirms the presence of reducing sugars.
What are the two charged regions of phospholipids?
Hydrophilic head and hydrophobic tail
What structure forms the plasma membrane around cells?
Phospholipid bilayer
What type of reaction forms triglycerides and phospholipids?
Condensation reaction
What type of bond is formed in triglycerides and phospholipids?
Ester bonds
What are the two types of fatty acids based on carbon bonds?
Saturated and unsaturated
What is the role of lipids in the nervous system?
Form the insulating myelin sheath on neurones to enable saltatory conduction
Where do lipids form the membrane within organelles?
Mitochondria and chloroplasts
Fill in the blank: Phospholipids have a _______ head and a hydrophobic tail.
Hydrophilic
Fill in the blank: The _______ tail of phospholipids is not exposed to water.
Hydrophobic
True or False: Phospholipids are non-polar molecules.
False
What is the composition of the phospholipid bilayer in relation to water?
Heads are exposed to water, tails are not
What type of vesicle is formed by lipids?
Phagosome
How do lipids contribute to viral structure?
Form an envelope around viruses such as HIV
What is the primary source of metabolic water?
Triglycerides can act as a metabolic water source
They can release water when oxidized, which is essential for animals in arid environments.
What property of triglycerides allows them to store a lot of energy?
Large ratio of energy-storing carbon-hydrogen bonds
This high ratio compared to the number of carbon atoms contributes to their energy storage capacity.
Do triglycerides affect water potentials and osmosis?
No, triglycerides do not affect water potentials and osmosis
They are large and hydrophobic, making them insoluble in water.
What is the advantage of lipids having a relatively low mass?
A lot can be stored without increasing mass and preventing movement
This property is beneficial for organisms needing mobility.
What are the components of phospholipids?
Glycerol, two fatty acid chains, and a phosphate group
These components create the structural basis of phospholipids.
What is the hydrophilic part of a phospholipid called?
Hydrophilic head
The hydrophilic head can attract water due to its charged nature.
What is the non-polar part of a phospholipid known as?
Hydrophobic tail
The hydrophobic tail repels water but will mix with fats.
What type of bonds are formed between fatty acids and glycerol in phospholipids?
Ester bonds
Two condensation reactions result in the formation of these bonds.
Fill in the blank: Phospholipids have a hydrophilic ______ and a hydrophobic ______.
head; tail
The head is charged and attracts water, while the tail is non-polar and repels water.
True or False: Phospholipids are soluble in water.
False
The hydrophobic tails make phospholipids insoluble in water.
What is the significance of the high ratio of hydrogen to oxygen in triglycerides?
It allows triglycerides to act as a metabolic water source
This is particularly important for animals in dry environments.
What are the two main types of lipids discussed?
Triglycerides and phospholipids
What is the structure of a triglyceride?
One molecule of glycerol and three molecules of fatty acid
What type of reaction forms triglycerides?
Condensation reaction
What type of bond is formed between glycerol and fatty acids in triglycerides?
Ester bond
What are the components of glycerol?
Three carbon atoms and hydroxyl groups
What are the two types of fatty acids?
Saturated and unsaturated
Fill in the blank: Saturated fatty acids have ________ bonds between carbons.
only single
Fill in the blank: Unsaturated fatty acids consist of at least one ________ bond between carbons.
double
What is the general formula of a triglyceride?
Glycerol + 3 Fatty Acids
Define saturated fatty acids.
Fatty acids with only single bonds between carbon atoms
Define unsaturated fatty acids.
Fatty acids that contain at least one double bond between carbon atoms
What is a competitive inhibitor?
A substance that competes with the substrate for the active site of an enzyme.
What happens to the rate of reaction when substrate concentration is high enough in the presence of a competitive inhibitor?
The rate of reaction returns to the same as with no inhibitor.
What is a non-competitive inhibitor?
A substance that decreases the rate of reaction regardless of substrate concentration.
How do enzymes lower activation energy?
Through the induced fit model.
What type of structure do enzymes have?
Tertiary structure proteins.
List three factors that affect the rate of reaction in enzymatic processes.
- Inhibitors
- Substrate concentration
- Enzyme concentration
True or False: Enzymes are not sensitive to temperature and pH.
False
Fill in the blank: Enzymes catalyse specific reactions due to their uniquely shaped _______.
[active site]
What is the effect of non-competitive inhibitors on the rate of reaction?
The rate of reaction is lower at all substrate concentrations.
Cyanide is an example of a _______ inhibitor for an enzyme in respiration.
[competitive]
How is enzyme sensitivity to pH and temperature linked to homeostasis?
It relates to thermoregulation and regulation of pH of the blood.
What is lysozyme?
A hydrolytic enzyme involved in phagocytosis.
What does the induced fit model demonstrate?
How enzymes lower activation energy.
How can enzyme function and sensitivity to temperature be linked to photosynthesis?
Through Rubisco.
What are competitive inhibitors?
Competitive inhibitors are the same shape as the substrate and can bind to the active site
They prevent the substrate from binding and the reaction occurring.
What happens when more substrate is added in the presence of a competitive inhibitor?
More substrate can out-compete the inhibitor, knocking them out of the active site
This allows the substrate to bind and the reaction to occur.
What is the function of non-competitive inhibitors?
Non-competitive inhibitors bind to the enzyme away from the active site, causing a permanent change in shape
This prevents the substrate from binding regardless of substrate concentration.
Where do non-competitive inhibitors bind?
Non-competitive inhibitors bind to the allosteric site
This is away from the active site.
What effect do non-competitive inhibitors have on the active site?
They cause the active site to permanently change shape
As a result, the substrate can no longer bind.
Fill in the blank: Competitive inhibitors prevent the substrate from binding to the _______.
active site
True or False: Non-competitive inhibitors can be out-competed by adding more substrate.
False
Non-competitive inhibitors permanently change the active site.
What happens to an enzyme when the pH is too high or too low?
The enzyme denatures and its active site changes shape
This occurs because the charges in the amino acids in the active site are interfered with, breaking ionic and hydrogen bonds.
What is the term for the complex formed when an enzyme binds with its substrate?
Enzyme-substrate complex
What is denaturation in the context of enzymes?
The process where an enzyme loses its tertiary structure and functionality
Fill in the blank: Different enzymes have a different optimal _______.
pH
How does insufficient substrate concentration affect the rate of reaction?
The reaction will be slower due to fewer collisions between the enzyme and substrate
What occurs if there are insufficient enzymes in a reaction?
The enzyme active sites become saturated with substrate and cannot work faster
What is meant by enzyme active site saturation?
All active sites of the enzymes are occupied by substrate, preventing further reaction increase
What are the key factors that affect the rate of enzyme reactions?
pH, substrate concentration, enzyme concentration
Each of these factors can influence how effectively enzymes catalyze reactions.
True or False: A higher concentration of substrate always increases the rate of reaction.
False
The rate of reaction can plateau if the enzyme active sites become saturated.
What are enzymes?
Proteins that act as catalysts in biochemical reactions
Enzymes lower the activation energy required for reactions.
What is meant by ‘successful collisions’ in the context of enzymes?
Collisions between enzyme and substrate that result in a reaction
Successful collisions are necessary for enzyme-substrate complexes to form.
What does it mean for an enzyme to be denatured?
The enzyme’s active site changes shape, preventing enzyme-substrate complexes from forming
Denaturation can be caused by extreme temperatures or pH levels.
List the factors affecting the rate of enzyme-controlled reactions.
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
- Inhibitors
Each factor influences the efficiency and speed of enzyme activity.
What happens to enzyme activity when the temperature is too low?
There is not enough kinetic energy for successful collisions
Low temperatures can slow down reaction rates significantly.
What happens to enzymes when the temperature is too high?
Enzymes denature and the active site changes shape
Denaturation results in the inability to form enzyme-substrate complexes.
At what point does temperature increase enzyme activity?
Up to the optimal temperature
Beyond this point, denaturation occurs and activity decreases.
Fill in the blank: The rate of reaction increases with temperature until the _______ is reached.
[optimal temperature]
True or False: Enzyme concentration affects the rate of enzyme-controlled reactions.
True
Higher enzyme concentrations can increase the rate of reaction, provided there is enough substrate.
What are the two models to explain enzyme action?
Lock and Key Model, Induced Fit Model
In the Lock and Key Model, what does the enzyme represent?
A lock
In the Lock and Key Model, what does the substrate represent?
A key
What is the shape of the enzyme active site in the Lock and Key Model?
Fixed shape
What forms when the substrate attaches to the enzyme in the Lock and Key Model?
Enzyme-substrate complex
What happens to the substrate when the enzyme-substrate complex is formed?
Charged groups distort the substrate, lowering activation energy
What occurs after the products are released from an enzyme?
The enzyme active site is empty and ready to be reused
In the Induced Fit Model, what does the enzyme represent?
A glove
In the Induced Fit Model, what does the substrate represent?
Your hand
How does the enzyme active site change in the Induced Fit Model?
It slightly changes shape to mould around the substrate
What effect does the enzyme moulding around the substrate have?
It puts a strain on the bonds and lowers the activation energy
What is the accepted model for how enzymes function?
Induced Fit Model
Fill in the blank: The _______ model suggests that the enzyme is like a lock and the substrate like a key.
Lock and Key
True or False: The Lock and Key Model suggests that the enzyme active site is flexible in shape.
False
What happens to the active site of the enzyme after the products are released in the Induced Fit Model?
Returns to its original shape
What is the site on an enzyme where a substrate attaches to catalyze a reaction?
Active site
The active site is specific and unique in shape due to the specific folding and bonding in the tertiary structure of the protein.
What determines the specificity of an enzyme for its substrate?
Complementary shape
Enzymes can only attach to substrates that are complementary in shape.
What is the term for the energy required for a reaction to occur?
Activation energy
All reactions require a certain amount of energy before they occur.
How do enzymes affect the activation energy of a reaction?
Lower the activation energy
When enzymes attach to the substrate, they can lower the activation energy needed for the reaction to occur.
Where are protein polymer chains, or polypeptides, created in cells?
Ribosomes
Polypeptides are then further folded and modified in the Golgi apparatus.
What type of structure is important for the function of enzymes?
Tertiary structure
The specific folding and bonding in the tertiary structure of the protein create the active site.
Fill in the blank: Enzymes speed up reactions by lowering the _______.
Activation energy
True or False: Enzymes can attach to any substrate regardless of shape.
False
Enzymes are specific and can only attach to substrates that fit their active site.
What happens to the activation energy requirement when an enzyme is present?
It decreases
This allows the reaction to occur more quickly.
What type of molecules are enzymes?
Relatively large molecules
Enzymes are large due to their polypeptide chains.
What is the tertiary structure of a protein?
The further folding of the secondary structure to create a unique 3D structure held in place by hydrogen, ionic, and disulfide bonds.
The tertiary structure is a critical aspect of protein functionality.
How are tertiary structures of proteins held in place?
By hydrogen bonds, ionic bonds, and sometimes disulfide bonds.
Disulfide bonds form between the R-groups of two amino acids containing sulfur.
What distinguishes the quaternary structure of a protein?
A protein made up of more than one polypeptide chain, still folded into a 3D shape and held by hydrogen, ionic, and disulfide bonds.
Haemoglobin is an example of a protein with quaternary structure, consisting of 4 polypeptide chains.
What is a prosthetic group in proteins?
Any group attached to a protein that is not made up of amino acids.
In haemoglobin, the heme group containing iron acts as the prosthetic group.
What is a conjugated protein?
A protein that has a prosthetic group added onto it.
Conjugated proteins play important roles in various biological processes.
List the types of bonds involved in maintaining protein structures.
- Hydrogen bonds
- Ionic bonds
- Disulfide bonds
These bonds are crucial for maintaining the unique shapes of proteins.
True or False: The secondary structure of proteins cannot be further folded.
False.
The secondary structure can be further folded to form the tertiary structure.
Fill in the blank: The _______ structure of a protein refers to its overall 3D shape formed by the folding of its secondary structure.
[tertiary]
What are the two main forms of secondary structure in proteins?
- Pleated sheet
- Alpha helix
These structures are key components of protein folding.
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain
It is essential to state the word ‘sequence’ for clarity.
How is the order of amino acids in a protein determined?
By DNA
The specific order of amino acids influences bonding and protein folding.
What determines the final 3D shape and function of a protein?
The primary structure
The specific sequence of amino acids alters where bonds occur.
How many different amino acids can form the primary structure of proteins?
20
These amino acids combine to create polypeptide chains.
What type of reactions create the polypeptide chain?
Condensation reactions
These occur between amino acids to form peptide bonds.
What holds the amino acids in the polypeptide chain together?
Peptide bonds
These bonds are formed during the condensation reactions.
What structures can the secondary structure of a protein form into?
a helix and B pleated sheets
These structures are influenced by the sequence of amino acids.
What type of bonds hold the secondary structure in place?
Hydrogen bonds
These form between the carboxyl groups of one amino acid and the amine group of another.
Fill in the blank: The first structure that forms in the creation of a protein is the _______.
polypeptide chain
True or False: The primary structure of a protein is vital for determining its 3D shape.
True
The primary structure directly influences folding and function.
What are proteins made up of?
Proteins are large polymers made up of monomers called amino acids.
What are the four levels of structural arrangements in a protein?
Primary, secondary, tertiary, quaternary.
Where are protein polymer chains created?
On ribosomes in cells.
What is the role of the Golgi apparatus in protein processing?
Proteins are further folded and modified.
What is the monomer in proteins?
Amino acid.
How many different amino acids are there?
20.
What is the general structure of an amino acid?
A central carbon, an amine group (NH2), a hydrogen atom, a carboxyl group (COOH), and a variable group (R group).
What connects amino acids to form polypeptides?
Peptide bonds.
How do amino acids join together to form polypeptides?
Via condensation reactions.
What does the ‘R’ in the general structure of amino acids represent?
The variable group.
True or False: Proteins can only have one level of structural arrangement.
False.
What is the primary function of cellulose in plants?
To provide structural strength
Cellulose is located in the cell wall of plants and prevents cells from bursting if they take in excess water.
What type of monomers make up cellulose?
B-glucose monomers
Cellulose is the only polysaccharide made up of B-glucose monomers.
What type of bonds join the monomers in cellulose?
1,4 - glycosidic bonds
These bonds create straight chains, unlike 1-6 bonds which create branches.
What is the structure formed by parallel chains of B-glucose in cellulose?
Fibril
Fibrils align in parallel and are held together by hydrogen bonds.
What are the three key disaccharides?
- Maltose
- Lactose
- Sucrose
These are important for understanding carbohydrate structures.
What are the three key polysaccharides?
- Starch
- Glycogen
- Cellulose
Each serves a distinct purpose in storage and structure.
What is the function of glycogen in animals?
Glucose storage
Glycogen serves as a storage form of glucose in animals.
What is the function of starch in plants?
Glucose storage
Starch acts as the storage form of glucose in plants.
What property of cellulose makes it insoluble?
Large molecule size
This property prevents it from changing the water potential of a cell.
Why is cellulose considered a strong polysaccharide?
Due to the large number of hydrogen bonds
Hydrogen bonds in and between the fibrils contribute to its strength.
Fill in the blank: Monomers join together by _______ reactions to make polymers.
condensation
These reactions are crucial in the formation of larger carbohydrate structures.
True or False: Cellulose is soluble in water.
False
Cellulose’s large size makes it insoluble, which is advantageous for cell water potential.
What is the structural arrangement of cellulose fibers?
Parallel chains held by hydrogen bonds
This arrangement provides structural integrity to plant cell walls.
What are the two isomers of glucose that exist?
- a-glucose
- B-glucose
These isomers have different structures and functions in carbohydrates.
What is glycogen?
The major carbohydrate storage molecule found in animal cells
Glycogen is primarily stored in liver and muscle cells.
Where is glycogen mainly stored in the body?
Liver and muscle cells
These cells ensure access to glucose for respiration and energy release.
How is glycogen formed?
From excess glucose that has been eaten and absorbed into the bloodstream
If more glucose is consumed than needed for respiration, it is converted into glycogen.
What is the primary function of glycogen in liver and muscle cells?
To ensure these cells have access to glucose to respire and release energy
Liver cells help remove toxins while muscle cells are responsible for movement.
What type of monomer makes up glycogen?
α-glucose
Glycogen is a polymer made from α-glucose monomers.
How are the monomers in glycogen joined together?
Via condensation reactions using 1,4 and 1,6-glycosidic bonds
This structure is similar to amylopectin in starch.
What is the key structural difference between glycogen and starch?
Glycogen contains more 1,6-glycosidic bonds and is more branched
This branching allows for more efficient glucose release.
Why is glycogen insoluble?
Because it is a large molecule
This property allows glycogen to be stored within cells without affecting water potential.
What advantage does the branched structure of glycogen provide?
A larger surface area for enzymes to attach
This allows glycogen to be hydrolysed into glucose more readily.
True or False: Glycogen is hydrolysed back into glucose more rapidly than starch.
True
This is essential for animals with higher metabolic rates.
Fill in the blank: Glycogen is even more branched than ______.
starch
This increased branching allows for faster glucose availability.
What is a primary reason animals need rapid access to glucose from glycogen?
To provide energy to run from a predator
Animals have a higher metabolic rate compared to other organisms.
What are the two polymers that make up starch?
Amylose and amylopectin
Starch consists of these two distinct structures which contribute to its overall function.
What type of bonds join the glucose monomers in amylose?
1,4 - glycosidic bonds
These bonds result in a spiral-shaped polymer structure.
What characteristic shape does amylose have?
Spiral-shaped
This spiral structure allows for compact storage of glucose.
What type of bonds join the glucose monomers in amylopectin?
1,4 and 1,6 - glycosidic bonds
The 1,6 bonds create branches in the structure.
What is the significance of the branched structure of amylopectin?
Provides a larger surface area for enzyme attachment
This enables more efficient hydrolysis back into glucose.
Why is starch insoluble in water?
It is a large molecule
This property allows starch to be stored within cells without affecting water potential.
What is the advantage of starch being insoluble?
It does not change the water potential of a cell
This prevents osmosis from occurring.
How does the structure of amylose contribute to its function?
It can be readily compacted
This compact nature is beneficial for storage.
Fill in the blank: Starch is readily hydrolysed back into glucose when plant cells are running low on _______.
glucose
This process is crucial for respiration in plant cells.
What is the chemical formula for glucose?
C6H12O6
Glucose is a vital monosaccharide involved in energy production and storage.
What are the two structural isomers of glucose?
- α-glucose
- β-glucose
Isomers have the same molecular formula but different structural arrangements.
What is the main function of glucose in biological systems?
Provides energy or forms structural support (cellulose) and energy storage molecules (glycogen and starch).
Glucose is a key energy source for cells.
What is the difference between α-glucose and β-glucose?
The hydrogen (H) and hydroxyl group (OH) on carbon 1 are in swapped positions.
This small change can significantly affect the polymers formed.
True or False: Isomers have the same structural arrangement.
False
Isomers differ in their structural arrangement despite having the same molecular formula.
Fill in the blank: Glucose can be polymerised to form _______.
cellulose, glycogen, starch
These polymers serve various functions including structural support and energy storage.
What type of biological molecules are monosaccharides?
Simple sugars
They are the building blocks of more complex carbohydrates.
What are polysaccharides?
Polymers made up of many monosaccharides
Polysaccharides are formed through condensation reactions.
What is the process by which polysaccharides are created?
Condensation reactions
This process is similar to the formation of disaccharides.
Name three key polysaccharides you need to learn.
- Starch
- Glycogen
- Cellulose
Understanding their structure and function is important.
What is the primary function of starch and glycogen?
Energy storage
Both serve as energy reserves for organisms.
What is the main function of cellulose?
Provides structural support
Cellulose is important for the integrity of plant cell walls.
Where is starch found?
In plants, not in animal cells
It is the major carbohydrate store in plants.
What is starch made from?
Excess glucose created during photosynthesis
When more glucose is produced than needed for respiration, it is converted to starch.
What type of glucose monomers make up starch?
a-glucose
Starch is a polymer specifically composed of a-glucose units.
How are the a-glucose monomers in starch joined together?
Via condensation reactions
These reactions form glycosidic bonds between the monomers.
What types of glycosidic bonds are present in starch?
- 1,4 - glycosidic bonds
- 1,6 - glycosidic bonds
These bonds refer to the carbon atoms they connect.
Fill in the blank: Starch is converted from glucose during _______.
[photosynthesis]
What are polysaccharides?
Polymers made up of many monosaccharides
Polysaccharides are formed through condensation reactions.
What is the process by which polysaccharides are created?
Condensation reactions
This process is similar to the formation of disaccharides.
Name three key polysaccharides you need to learn.
- Starch
- Glycogen
- Cellulose
Understanding their structure and function is important.
What is the primary function of starch and glycogen?
Energy storage
Both serve as energy reserves for organisms.
What is the main function of cellulose?
Provides structural support
Cellulose is important for the integrity of plant cell walls.
Where is starch found?
In plants, not in animal cells
It is the major carbohydrate store in plants.
What is starch made from?
Excess glucose created during photosynthesis
When more glucose is produced than needed for respiration, it is converted to starch.
What type of glucose monomers make up starch?
a-glucose
Starch is a polymer specifically composed of a-glucose units.
How are the a-glucose monomers in starch joined together?
Via condensation reactions
These reactions form glycosidic bonds between the monomers.
What types of glycosidic bonds are present in starch?
- 1,4 - glycosidic bonds
- 1,6 - glycosidic bonds
These bonds refer to the carbon atoms they connect.
Fill in the blank: Starch is converted from glucose during _______.
[photosynthesis]
What are disaccharides?
Two monosaccharides bonded together by a glycosidic bond formed by a condensation reaction.
What is a glycosidic bond?
A bond formed between two monosaccharides during a condensation reaction.
What is the result of the condensation reaction between glucose and glucose?
Maltose
What is the result of the condensation reaction between glucose and galactose?
Lactose
What is the result of the condensation reaction between glucose and fructose?
Sucrose
Fill in the blank: Disaccharides are formed by the _______ of two monosaccharides.
[bonding]
What reaction breaks down disaccharides back into monosaccharides?
Hydrolysis reaction
True or False: Hydrolysis involves adding a water molecule to break a bond.
True
In a glycosidic bond, which carbons are involved in a 1-4 glycosidic bond?
Carbon 1 and Carbon 4
What happens during a condensation reaction in the formation of disaccharides?
A water molecule is removed from the hydroxyl groups.
What are the three key disaccharides to remember?
- Maltose
- Lactose
- Sucrose
What is the main function of a glycosidic bond in carbohydrates?
To link monosaccharides together to form disaccharides.
What are the three main types of carbohydrates?
Monosaccharides, Disaccharides, Polysaccharides
These classifications are based on the number of sugar units.
Define monosaccharides.
Monomers of carbohydrates, soluble in water
Examples include glucose, galactose, and fructose.
What is the general formula for a monosaccharide?
CH₂nOn
Where n = the number of carbon atoms.
What are three common examples of monosaccharides?
Glucose, Galactose, Fructose
What are disaccharides?
Dimers of carbohydrates formed from two monosaccharides
Examples include maltose, sucrose, and lactose.
What are polysaccharides?
Polymers of carbohydrates made from many monosaccharides
Examples include starch, glycogen, and cellulose.
What is the function of monosaccharides?
To provide energy or serve as building blocks for larger molecules
What elements do all carbohydrates contain?
Carbon, Hydrogen, Oxygen (CHO)
True or False: Carbohydrates can provide structural support to plant cells.
True
Fill in the blank: Carbohydrates are key biological molecules that store _______.
energy
Name a larger carbohydrate that is a disaccharide.
Sucrose
Other examples include maltose and lactose.
What type of carbohydrates are starch and glycogen classified as?
Polysaccharides
What are the three main types of carbohydrates?
Monosaccharides, Disaccharides, Polysaccharides
These classifications are based on the number of sugar units.
Define monosaccharides.
Monomers of carbohydrates, soluble in water
Examples include glucose, galactose, and fructose.
What is the general formula for a monosaccharide?
CH₂nOn
Where n = the number of carbon atoms.
What are three common examples of monosaccharides?
Glucose, Galactose, Fructose
What are disaccharides?
Dimers of carbohydrates formed from two monosaccharides
Examples include maltose, sucrose, and lactose.
What are polysaccharides?
Polymers of carbohydrates made from many monosaccharides
Examples include starch, glycogen, and cellulose.
What is the function of monosaccharides?
To provide energy or serve as building blocks for larger molecules
What elements do all carbohydrates contain?
Carbon, Hydrogen, Oxygen (CHO)
True or False: Carbohydrates can provide structural support to plant cells.
True
Fill in the blank: Carbohydrates are key biological molecules that store _______.
energy
Name a larger carbohydrate that is a disaccharide.
Sucrose
Other examples include maltose and lactose.
What type of carbohydrates are starch and glycogen classified as?
Polysaccharides
