Biological Molecules Flashcards
What is a Monomer?
Small units from which larger molecules are made.
What is a Polymer?
Molecules made from a large number of similar monomers joined together.
Give 3 exapmles of momomers.
Monosaccharides
Amino acids
Nucleotides
What is a condensation reaction?
Reaction that joins two molecules together which eliminates a water molecule.
What is a Hydrolysis reaction?
A reaction that breaks a chemical bond and involves the usage of a water molecule.
What elements are in a carbohydrate?
Carbon
Hydrogen
Oxygen
What is a monosaccharide?
Monomer of carbohydrates
What are glucose isomers?
Alpha glucose
Beta glucose
What is a disaccharide?
Formed when two monosaccharides are joined together by a glycosidic formed by a condensation reaction.
What is the equation for Maltose
Glucose + Glucose > Maltose + Water
What is the equation for Sucrose?
Glucose + Fructose > Sucrose + Water
What is the equation for Lactose?
Glucose + Galactose > Lactose + Water
What is Hydrolysis of a disaccharide.
Breaks down disaccharide into monosaccharide with the addition of water
Maltose + Water > Glucose + Glucose
What does the benedicts test test for?
Reducing sugars
Describe the Qualitative Benedicts test.
• Add sample in tube with benedict’s solution
• heat to 95° in water bath
• If it turns brick red/orange the test is +ve
• If it remains blue then its -ve
What is a Semi-Quantitative Benedicts test?
Test where the colour intensity depends on the concentration of reducing sugar in the solution.
It is SUBJUNCTIVE
What do the colours mean in a Semi-Quantitative Benedict’s test?
Brick red - high conc of reducing sugar
Orange - medium conc
Yellow/Green - low conc
Blue - no reducing sugar
What is a Quantitative Benedict’s test?
Test carried out to obtain numerical data to compare reducing sugar concentrations in different samples.
Its OBJECTIVE
Describe a Quantitative Benedicts test.
• Do Benedict’s test on reducing sugars of know concentrations
• Variables must be controlled ( same volume of Benedicts solution, heat for same time)
• Use a colorimeter to measure the absorbance of each solution
• ploy a graph (conc on x-axis absorbance on y-axis)
Describe the test for a non-reducing sugar?
• perform benedict’s test to confirm -ve result
• Hydrolyse another sample of reducing sugar in water bath with dilute acid
• when cooled neutralise with alkali
• add same conc of benedicts solution and heat
• if brick red = positive result
Name three polysaccharides.
Cellulose
Glycogen
Starch
Describe polysaccharides.
• relatively insoluble in water
• non-reducing
• either storage or structural molecules
Describe Starch Molecule
• long chains of alpha glucose
• linked by glycosidic binfs
• large (cant cross cell surface membrane)
• insoluble (osmotically inactive)
• helical shape, compact store
• branched so glucose is easily released for respiration
What is the function of starch?
Storage carb found in plants
- Stored in starch grains in the cytoplasm
How can you test for Starch?
Iodine test
• add 2-3 drops of iodine to sample
• positive result = blue/ black colour
• negative result = orange/yellow
Describe Glycogen.
• found in cytoplasm of animal cells
• similar to starch but more branched (can release glucose more rapidly)
• insoluble (osmotically inactive)
• formed by condensation of alpha glucose
Where is Glycogen stored?
Liver and Muscle tissues
What is the function of Glycogen?
Storage compound
Describe Cellulose
• polymer of beta glucose
• long straight chains
• in cell wall if plants
What is the function of Cellulose
Provides rigidity and shape to cell
How is the structure of Cellulose formed?
• beta glucose form hydrogen bonds
• hydroxyl groups form microfibrils with provide strength
What is in a Triglyceride molecule
3 fatty acids
1 glycerol
joined in 3 condensation reactions
What is the general formula for a fatty acid?
R-COOH
What is a Saturated fatty acid?
No double binds between carbon atoms
What is an unsaturated fatty acid?
One or more double bonds between carbon atoms
How can you hydrolyse a Lipid?
• heat with acid or alkali
• use enzyme lipase at its optimum temperature and pH
What are some of the properties of a Triglyceride?
• high amount of C-H bonds so release 2x energy as Carbs during respiration
• high ratio of hydrogen to oxygen atoms releasing water when respired ( important for organisms in dry habitats)
• Non-polar, insoluble, osmotically inactive (ideal storage compounds)
• in the waxy cuticle of an insect and plant leaves to help reduce water loss
What is in a Phospholipid?
1 phosphates group
1 glycerol
2 fatty acids
Describe the Phospholipid head and tail?
• Polar hydrophilic head ( phosphate group) attract water
• Non-polar hydrophobic tail (fatty acids) repel water
Describe the Phospholipid layer?
•Head and tail form a bilayer, two layers of phospholipids due to the tails being repelled by water
• the tails face eachother
Outline the emulsion test.
• add sample to tube with ethanol
• shake so fat dissolves
• add water and mix
• white emulsion of fat = lipid present
What properties do Triglycerides and Phospholipids share?
both:
- insoluble in water
- contain glycerol
- contain ester bonds
What is an amino acid?
monomers that form proteins
How are amino acids joined together.
By peptide bonds (CONH) formed by condensation reactions
What is the primary protein structure?
The sequence of amino acids in the polypeptide chain. Determines shap of protein
What is the Secondary Protein Structure
• Folding of the polypeptide chain
• Due to hydrogen bonding between amino acids
What is the Tertiary Protein Structure?
• further folding of the polypeptide chain
• due to ionic, hydrogen and disulphide bonds
• determined by location and interactions if R groups in amino acids
What is a Quaternary Protein Structure?
• Protein’s consist of more that 1 polypeptide chain
• Held together by ionic, hydrogen and sometimes disulfide bonds
Describe a Globular Protein.
• soluble and highly folded polypeptide chain
• produces a compact tertiary structure
• include enzymes and antibodies
What is Denaturation of a protein?
Alteration in the tertiary structure of a protein
What can cause denaturation of a Protein?
• high temperature
• breaking of hydrogen/ionic bonds
• extreme changes in pH
• heavy metals
Describe the Biuret test for Proteins?
• add biuret reagent
• purple/lilac colour = protein present
• remains blue = negative
How does water act as a Metabolite?
• used as a metabolite in hydrolysis and condensation
• needed for respiration
• product of respiration (important for organisms in dry habitats)
How is water used as a Solvent?
• transports nutrients e.g glucose in blood
• removes excretory products (urea)
• a medium where metabolic reactions occur
How does water regulate temperature ?
• has high heat capacity
• has large latent heat of vapourisation
How does water having high heat capacity regulate temperature?
• means it can absorb large amount of heat energy before rising in temp
• this is bc energy is being absorbed by hydrogen bonds
- this minimises increase in temperature in cells
- prevents fluctuations of temperature in aquatic habitats
How does water having latent heat of vaporisation regulate temperature?
• lots of energy is required to break hydrogen bonds and evaporate water
• provides cooling effect due to little loss of water thru evaporation
- helps animals maintain constant body temp
How does water act as an Internal support?
• cohesive forces (due to hydrogen bonds) support water columns in tube like transport cells
• this allows transport from roots to leaves
• water isn’t easily compressed and provides support in non woody plants via turgor pressure
How does water act as an External support?
Strong cohesive forces (due to hydrogen bonds) produce surface tension where water meets air
• allows insects to walk on water or be suspended at the surface
• provides buoyancy for aquatic organisms
What role does the inorganic ion Sodium have?
co transport of glucose and amino acids across cell membranes
Role of inorganic ion Iron
Component of haemoglobin which transports oxygen
Role of inorganic ion Hydrogen
important in determining pH thus effecting protein structure and enzyme activity
Role of inorganic ion Phosphate
Important as a structural component of DNA RNA and ATP
How do enzymes work
lower activation energy
Describe the induced fit model
active site is flexible and can change shape ans moulds around correct substrate
How does substrate concentration affect enzymes?
increases collisions between substrate and enzyme
then levels out as active site becomes taken up
rate of reaction can be increased again by adding more enzymes
how does enzyme concentration affect enzyme reaction?
(substrate must me in excess)
when theres more enzymes there’s more active sites available
increasing collisions
how does temperature affect enzyme reaction
gives molecules more kinetic energy meaning more collisions
after optimum temperature tertiary structures denatures as hydrogen bonds are broken
active site changes shape
how does ph affect enzyme reaction
enzymes have an optimum pH
different pH from the optimum can cause denaturariom
what is a competitive inhibitor
has similar structure to substrate and competes for attachment to active site
rate of reaction reduced as substrates cant bind
can be reduced by adding more substrate
What is a non competitive inhibitor
binds to enzymes anywhere other than active site which alters tertiary structure
adding substrate wont reduce this
What is ATP used for?
immediate energy source in biological processes
What is in ATP
adenine
ribose
three phosphates
How does ATP release energy
it is continuously hydrolysed
What is the equation for the hydrolysis of ATP
ATP + (atp hydrolase) > ADP + inorganic phosphate
What is the equation for the syntheses of ATP
ADP + Pi + ( energy from respiration) > ATP
