Biological Molecules Flashcards
Why do all living things have a similar biochemical basis?
Monomers and polymers of four kinds of organic polymers: lipids, carbs, proteins and nucleic acids.
What is a monomer?
Small identical (or similar) molecules joined together to make polymers.
What is a polymer?
Large molecules made from joining many identical monomers.
Examples of monomers
B-glucose, Nucleotides, a- glucose etc.
Examples of polymers?
Polynucleotides, Cellulose, Amylose.
Describe a condensation reaction.
Joining two monomers with the removal of one water, forming a bond.
Describe Hydrolysis
Adding one water molecule to break the bond between two monomers.
Test for reducing and non-reducing sugar.
Reducing: benedicts, heat 95 for 5 mins, blue to brick red.
Non-reducing: negative benedict’s, HCL, boil for 5 mins, NaHCO3, benedict’s test, brick red ppt.
Two monomers of glucose and their differences
A and B glucose.
B glucose has the same structure but the H and OH group are inverted on C1
Describe how the three disaccharides are formed? (Maltose, Lactose, Sucrose)
Condensation reaction, 1-4 glycosidic bond, producing water.
glucose + glucose –> maltose
glucose + galactose –> lactose
glucose + fructose –> sucrose
How are polysaccharides formed?
Polymer formed by joining many monosaccharides together.
Describe how larger carbohydrates are formed from monosaccharides.
Condensation reaction between monosaccharides forming a glycosidic (covalent) bond and producing water, catalysed by an enzyme.
Structure of Glycogen and Starch?
A glucose
condensation reaction
1-4 and 1-6 glycosidic bonds producing water
Branched + Helical/ highly branched
Large insoluble
compact.
Test for starch?
iodine brown/orange to blue/black
Formation of Cellulose?
B glucose
Long straight chains
Every other B glucose rotates 180
1-4 glycosidic bonds cond reaction water.
H bonds between chains
Microfibrils
High tensile strength, support and rigidity, resists turgor pressure.
Structure to Function of Starch?
Plants
Compact- lot in a small space
Large and Insoluble- no effect on water potential.
Branched allow hydrolysis of terminal glucose for respiration.
Structure to Function glycogen
Animals
Compact- lot in a small space
Large and Insoluble- no effect on water potential.
Highly Branched allow hydrolysis of terminal glucose for respiration.
Structure to function of cellulose
Long unbranched chains with H bonds in between forming strong microfibrils which resist turgor pressure.
What are lipids made from
Glycerol, fatty acids (and phosphate)
Roles of lipids
Dense Storage Molecule
Forms membranes
Insulation
Protection
How can lipids be fats/oils ?
Saturated/ unsaturated fatty acids R groups:
Double/ No double bonds
(Only single bonds)
H can/cannot be added
Long straight chains/ kinked chains.
Stronger/Weaker IMF
Higher/Lower MP
Solid/Liquid at rtp
Test for lipids?
Ethanol + water mix, colourless to positive cloudy white emulsion.
Formation of Triglycerides.
One glycerol, three fatty acids, 3 cond reactions, 3 waters, 3 ester bonds.
Formation of phospholipids.
One phosphate, oen glycerol, 2 fatty acids. Hydrophobic tails, hydrophilic head, 2 ester bonds.
Structure of Triglycerides relate to their properties?
High ratio of C-H bonds to C atoms, better at storing energy.
Low Mass- Energy ratio makes for better energy storage.
Large and non polar no effect on water potential.
High ratio of H- O atoms so good source of H2O.
General structure of an Amino acid
Amine and Carboxyl group with C bonded to ONE H and ONE R grp.
Structure relates to function for phospholipids.
Phospholipids form a bilayer in water, cell surface membrane. Allows lipid soluble molecules in, polar molecules cant pass through membrane.
How can a functional protein contain one or more polypeptides?
Enzymes are made up of one polypeptide chain and only have a tertiary structure.
Quaternary proteins have multiple chains and possibly a prosthetic group. e.g haemoglobin has 4 polypeptide chains and iron 2 ion.
How many different types of Amino Acids are there and how are they different?
Around 20 Amino Acids.
Differ in R groups.
How does a polypeptide form.
Amino acids join together in condensation reactions to form a polypeptide chain and water with peptide bonds.
Primary to Quaternary structures of proteins?
Primary: Number and Sequence of Amino Acids.
Folds and H bonds between Amine and Carboxyl Groups
Secondary: A helix or B pleated sheets.
Folds and Bonds form between R groups, H, Ionic, disulphide bridges, hydrophilic hydrophobic interactions.
Tertiary: Unique specific 3d shape.
Folds, may join with other polypeptide chains, addition of prosthetic group.
Quaternary: Functional Protein such as haemoglobin.
Explain how all proteins have a variety of function within all living organisms.
Their roles depend on their molecular shape,
either fibrous proteins, or globular proteins.
Can you relate the structure of proteins to a variety of proteins? Globular and fibrous proteins.
Globular: Coiled/Spherical, hydrophilic out phobic in, soluble
Roles in Metabolic reactions (enzymes)
Fibrous: long/unbranched,
philic in phobic out
insoluble
Structural roles
(keratin/collagen)
Can you describe the role of hydrogen bonds, ionic bonds, and disulfide bridges in the structure of proteins?
Disulfide bridges:
~ Fairly strong and therefore not easily broken.
- Ionic bonds:
~ Formed between any carboxyl and amino groups that are not involved in forming peptide bonds.
~ They’re weaker than disulfide bridges and are easily broken by changes in pH. - Hydrogen bonds:
~Numerous but easily broken.
Forms tertiary structure, affects active site of enzymes, changes in these bonds can denature enzymes
Test for Proteins.
Biuret reagent, shake vigorously, blue to lilac and foam
Can you explain how each enzyme lowers the activation energy of the reaction it catalyses?
stressing/ bending bonds in substrate
during formation of ES complex.
Describe how you would measure the rate of an enzyme-catalysed reaction and explain the results you would expect?
Conc of products, Conc of reactants
High initial rate of reaction, rate decreases until graph plateaus.
How does an enzyme’s structure relate to its function?
Specific tertiary structure due to specific order of amino acids.
active site complementary to their specific substrate.
Can you describe the induced-fit model of enzyme action?
Active site not initially complementary
Substrate causes a change in shape of the active site as it binds forming ES complex.
Substrate released as products, leaving the enzyme to revert back to its original shape.
Can you describe how models of enzyme action have changed over time?
Lock and Key: active site always complementary.
Induced fit: active site changes shape to become complementary and reverts back after catalysis complete.
How does the temperature affect the rate of an enzyme-controlled reaction?
As Temp increases, rate increases up to optimum. more frequent successful collisions.
After optimum, R group Bonds break change shape of active site.
Denaturation.
How does the pH affect the rate of an enzyme-controlled reaction?
rate increases closer towards optimum ph.
away from optimum increased conc of H+/OH- ions cause charges of AA to become altered, breaking ionic bonds and altering the shape of the active site or repelling the substrates.
How does the substrate concentration affect the rate of an enzyme-controlled reaction?
As conc increases, rate increases until it becomes constant.
All active sites become occupied (V max) and conc of enzyme becomes the limiting factor
How does the enzyme concentration affect the rate of an enzyme-controlled reaction?
Increase enzyme conc increases rate until reactants are no longer in excess, then no further effect.
How does the concentration of competitive inhibitor affect the rate of an enzyme-controlled reaction?
inhibitor has similar shape to substrate, compete for enzymes active site.
If substrate conc increases, inhibitor effect reduced.
Inhibitor only temporarily binds to active site, temporarily reducing rate of reaction.
Time until rate returns to original is dependent on conc of inhibitor.
How does the concentration of non-competitive inhibitor affect the rate of an enzyme-controlled reaction?
Attach to allosteric site, changing shape and denaturing active site/enzyme.
Permanently reducing rate of reaction by reducing number of available active sites.
Enzyme can no longer function properly and increase in substrate has no effect on the inhibitor.
what is End product inhibition
Chain of Enzyme catalysed reactions produce the final desired product which is an inhibitor of the initial enzyme that began the chain, halting the reaction chain.
