biological molecules Flashcards
what is a monomer
smaller repeating units from which larger molecules are made
what are polymers
moleculea made up from many monomers joined together
what is a condensation reaction
joins two molecules together with the formation of a chemical bond and involves the elimination of a water molecule
what is hydrolysis
breaks a chemical bond between two molecules and involves the use of a water molecule
what does a carbohydrate contain
carbon, hydorgen and oxygen
commonly used by cells as respiratory substrates and from structural components in plasma membranes and cell walls
what is a monosacharide
monomers from which larger carbohydrates are made.
example of a monosacharide
glucose, galactose, fructose
all have the formula C6 H12 O6
what is a isomer
share the same chemical formula but have different structures
e.g. alpha glucose and beta glucose
what is the difference between alpha and beta glucose
on carbon one the position of the hydrogen and carboxyl group are inverted
alpha glucose reads ho ho on the bottom whereas beta is ho h
what is a dissacharide
formed by condensation of two monosacharides with a glycosidic bond
they are soluble in water and have the formula of C12 H22 O11
examples of a dissacharide
- maltose = two glucose
- sucrose = glucose and fructose
- lactose = glucose and galactose
what is starch and what are its properties
- polysacharide found in plant cells made up of alpha glucose
- 1,4 and 1,6 glycosidic bonds
- when hydrolysed releases glucose for respiration
- insoluble in water
- large molecule so cant cross cell surface membrane
- branched and coiled which makes it compact, fits many alpha glucose in a small area
- branched so faster hydrolysis
glycogen and its properties
- polysacharide found in the liver and muscle cells made up of alpha glucose
- 1,4 and 1,6 glycosidic bonds
- coiled which makes it compact for storage of many glucose molecules
- branched, more ends so faster hyrdolysis to rapidly release glucose for respiratory substrate to release ATP
- insoluble, not easily lost from the cell, does not affect water potential
cellulose and its properties
- polysacharide found in plant cell walls
- beta glucose
- 1,4 glycocidic bonds
- every other b glucose must be inverted
- long straight chains which link together by many H bonds to form microfibrils the fibrils
- this gives mechanical strength
what is the test for reducing sugars
- add benedicts solution
- heat
- positive result will be red precipitate
what is the test for non reducing sugars
- obtain negative result with benedicts sugar test
- boil with acid
- neutralise with NaHCO3
- heat with benedicts
- positive result is red precipitate
starch test
iodine solution stains blue black in the presence of starch
what are the two quantitiave methods used to see how much sugar is present in a benedicts test
1) produce a dilution series of known concentration of glucose solutions. Use a colorimeter measure the absorbance of the solution after carrying out a benedicts test, the higher the absorbance the more sugar is present. Use this data to plot a calibration curve.
2) filter and dry precipitate then find the mass using a balance. The bigger the mass the more sugar is present.
what is chromatography
technique used to seperate a mixture into its individual components.
relies on differences in solubility of the different solutes within a mixture.
higher the solubilty the further it will travel.
monosacharides are colourless so will stain first.
a spot of the stained monosacharide sample mixture is placed on a line at the bottom of the chromatography paper.
spots of knwon standard solutions of different monosacharides are placed on the line beside the sample spot.
structure and function of a tryglyceride
- contains carbon, hydorgen, oxygen
- insoluble
- formed when a condensation reaction occurs between glycerol and 3 fatty acids to form an ester bond
- hydrophobic / non polar
structure and function of phospholipids
- contain carbon, hydrogen, oxygen and phosphorus
- insoluble
- glycerol, 2 fatty acids and a phosphate
- both hydrophobic tails and hydrophillic heads
- allows formation of the phosphlipid bilayer
emulsion test for lipids
- add ethanol
- shake
- add water
- shake
- positive test will show cloudy white emulsion
What are the building blocks of proteins?
Amino acids
How many standard amino acids are there?
20
What is a dipeptide?
A molecule formed from two amino acids linked by a peptide bond.
What type of bond connects amino acids in a protein?
Peptide bond
What level of protein structure is characterized by the sequence of amino acids?
Primary structure
True or False: The secondary structure of proteins involves the folding of the polypeptide chain.
False
What are the two main types of secondary structures in proteins?
Alpha helices and beta sheets
What level of protein structure involves the overall three-dimensional shape?
Tertiary structure
True or False: Quaternary structure involves the assembly of multiple polypeptide chains.
True
What determines the tertiary structure of a protein?
Interactions between R groups of amino acids.
Fill in the blank: A polypeptide chain is made up of a sequence of _____ linked by peptide bonds.
Amino acids
What type of interactions can stabilize tertiary structure?
Hydrogen bonds, ionic bonds, and disulfide bridges.
What is the effect of denaturation on protein structure?
It disrupts the secondary, tertiary, and quaternary structures without breaking peptide bonds.
Which level of protein structure is not affected by denaturation?
Primary structure
What is a common example of a protein with quaternary structure?
Hemoglobin
Which amino acid contains sulfur and can form disulfide bonds?
Cysteine
Fill in the blank: The sequence of amino acids in a protein is determined by the _____ of the gene encoding that protein.
DNA sequence
How do dipeptides form?
Through a condensation reaction between two amino acids.
What is the significance of the R group in amino acids?
It determines the properties and function of the amino acid.
What is a peptide bond?
A covalent bond formed between the carboxyl group of one amino acid and the amino group of another.
True or False: All proteins have a quaternary structure.
False
What level of protein structure is represented by alpha helices and beta sheets?
Secondary structure
what is the general structure of an amino acid
NH2 ( represents amine group), COOH ( represents carboxyl ) and R ( side chain )
buiret test for protiens
- add biuret reagent
- if protien is present colour will change purple
- if test is negative colour will remain blue
how do you seperate protiens and amino acids
1) paper chromatography
- unknown amino acid placed on origin line
- different aa will have different solubilities so wil travel different distanes dependant on size and charge
- unknown is compared to the known standards for identification
2) gel electropherisis
- seperates based on size and mass of the protien and the charge on the protiens
What is the primary function of enzymes?
To act as catalysts that speed up chemical reactions in biological processes.
True or False: Enzymes are consumed in the reactions they catalyze.
False
What is the active site of an enzyme?
The region on the enzyme where substrate molecules bind and undergo a chemical reaction.
Fill in the blank: Enzymes are typically ________ proteins.
globular
What model describes enzyme-substrate interaction where the enzyme changes shape to fit the substrate?
Induced fit model
What is the effect of temperature on enzyme activity?
Enzyme activity generally increases with temperature up to an optimal point, after which it decreases due to denaturation.
Multiple Choice: Which factor does NOT affect enzyme activity?
Color of the enzyme
What is the role of coenzymes in enzyme function?
Coenzymes assist enzymes by transferring chemical groups or electrons during reactions.
True or False: Enzymes can catalyze multiple types of reactions.
False
What is enzyme specificity?
The ability of an enzyme to choose exact substrate from a group of similar chemical molecules.
Fill in the blank: The ________ concentration of substrate typically increases the rate of enzyme-catalyzed reactions.
substrate
What happens to enzymes at high substrate concentrations?
They become saturated, and the reaction rate reaches a maximum velocity (Vmax).
Multiple Choice: What is an enzyme inhibitor?
A substance that decreases enzyme activity.
What are allosteric sites?
Sites on an enzyme where molecules can bind and change the enzyme’s activity.
True or False: Competitive inhibitors bind to the active site of an enzyme.
True
What is the significance of the enzyme-substrate complex?
It is the intermediate formed when an enzyme binds to its substrate, leading to a chemical reaction.
Fill in the blank: Enzymes are sensitive to ________ changes in pH.
changes
What does a high enzyme concentration imply for reaction rates?
It can lead to an increased rate of reaction, assuming substrate is available.
Multiple Choice: Which of the following is NOT a factor affecting enzyme activity?
Presence of light
What is denaturation in relation to enzymes?
The process where an enzyme loses its three-dimensional structure, resulting in loss of function.
True or False: Enzymes can function outside of their optimal temperature and pH.
False
What is the term for the maximum rate of an enzyme-catalyzed reaction?
Vmax
Fill in the blank: Enzymes are typically ________ under optimal conditions.
most active
What is the role of feedback inhibition in metabolic pathways?
It regulates the activity of enzymes to prevent overproduction of substances.
Multiple Choice: Which type of inhibitor changes the shape of the enzyme?
Non-competitive inhibitor
What happens to enzyme activity if the temperature exceeds its optimum level?
The enzyme may denature, leading to a decrease in activity.
What is the primary factor that affects the rate of enzyme-controlled reactions?
Enzyme concentration
True or False: Increasing substrate concentration always increases the rate of reaction.
False
Fill in the blank: The optimal _____ is the temperature at which an enzyme’s activity is highest.
temperature
What effect does pH have on enzyme activity?
Each enzyme has an optimal pH; deviations can reduce activity.
Multiple Choice: Which of the following factors does NOT affect enzyme activity? A) Temperature B) pH C) Substrate concentration D) Color of the enzyme
D) Color of the enzyme
What happens to enzymes at temperatures significantly above their optimal temperature?
They denature and lose activity.
Define ‘enzyme substrate complex’.
The temporary complex formed when an enzyme binds to its substrate.
True or False: Competitive inhibitors increase the rate of enzyme reactions.
False
What is the role of coenzymes in enzyme reactions?
They assist enzymes by transferring specific atoms or functional groups.
Short Answer: Name one way to measure the rate of an enzyme-controlled reaction.
By measuring the amount of product formed over time.
What is the main purpose of the required practical investigating the effect of a named variable on the rate of enzyme activity?
To determine how changes in a specific variable affect the rate at which enzymes catalyze reactions.
True or False: Enzymes are affected by temperature, pH, and substrate concentration.
True
Fill in the blank: The variable that is systematically changed in an experiment is called the _____ variable.
independent
What is the dependent variable in an experiment investigating enzyme activity?
The rate of the enzymatic reaction.
Which enzyme is commonly used in experiments to investigate the effect of temperature on enzyme activity?
Catalase
Multiple Choice: Which factor would likely increase the rate of an enzyme-catalyzed reaction? A) Lowering the temperature B) Increasing substrate concentration C) Decreasing pH
B) Increasing substrate concentration
What is the effect of extreme pH levels on enzyme activity?
Extreme pH levels can denature enzymes, leading to a decrease in activity.
Short Answer: Name one method to measure the rate of enzyme activity.
Measuring the volume of product formed over time.
True or False: Each enzyme has an optimal temperature at which it works best.
True
What is the term for a substance that increases the rate of an enzyme-catalyzed reaction without being consumed?
Catalyst
what is phosphorylation
addition of a phosphate
makes substrates more reactive
can change active site of an enzyme so it is complementary to the substrate ( activates enzyme )
