3.1 Biological Molecules Flashcards
Covers: - Carbohydrates, Proteins, lipids, enzyme action, factors affecting enzyme activity, enzyme controlled reactions, DNA & RNA, DNA Replication, Water, ATP, Inorganic Ions
What are the 3 most common carbohydrates?
Glucose, galactose, fructose.
Define isomers.
Same chemical formula but different chemical structures.
What are the 2 isomers of glucose and what is the main difference between them?
2 Isomers: Alpha and beta glucose
They’re essentially the same, C6H12O6 However, on the beta glucose, on C1, the OH group is at the top.
What’s a condensation reaction?
One which water is removed from
What bond is formed after condensation reaction of glucose?
1,4 Glycosidic bond
What are the monosaccharides of the disaccharide of maltose?
2 alpha glucose
What are the monosaccharides of the disaccharide of lactose
Glucose and galactose
The monosaccharides of sucrose
Glucose and fructose
What’s hydrolysis?
Splitting with water molecule.
Draw structure of amylose
Straight chain.
Between what carbons are bonds formed, what type of bond formed and why does it have a helical structure?
Helical as it can have hydrogen bonds formed between the chain. Forms 1,4 glycosidic bonds.
What’s the structure of amylopectin?
between what carbons are glycosidic bonds formed
Branched.
1,4 & 1,6.
How is starch adapted to its function?
- Compact, store a lot of starch in plant and takes less space
- Insoluble - so it doesn’t affect water potential therefore not too much water can enter or leave the cell. No osmotic effect.
- Glucose storage doesn’t leave cell.
Structure of glycogen, why it’s adapted to its function and between what carbons are bonds formed?
- HIGHLY branched
- energy store/glucose storage in animals, so high branched allows more energy
- MORE 1,6 Bonds and fewer 1,4 glycosidic bonds.
- More compact than starch
- insoluble
What’s structure of cellulose? Why is structure useful for properties and function?
B glucose used. Alternative glucose flips 180 degrees. Long and single chains gives mechanical strength to cell walls. For structural support in plants. It’s full of glucose molecules but most animals can’t digest it as we don’t have the right enzymes. Hydrogen bonds can form between chains and can form MICROFIBRILS.
What’s the monomer of protein? Draw structure of monomer. How many different monomers are there? What causes them to be different?
Amino acid. Structure of amino acid drawn - central carbon, amino group, carbonyl group, R group and H. Different as have different R groups.
Draw structure of peptide bond. How are peptide bonds formed
–C(O)NH–
Peptide bonds formed through condensation reactions.
What are the 4 levels of polypeptide structure? Describe the types of bonding in each and appearance.
Primary: Sequence of amino acids
Secondary: Hydrogen bonds between amino acids and carboxyl groups –> Forms alpha helix and or beta pleated sheets.
Tertiary: Interaction of R groups form new bonds. More H bonds, ionic bonds and disulfide birdges. The Alpha helic is folded and forms complex 3d structure.
Quarternary: 2 or more polypeptide chains joined together. 3D structure important to function which is deteremined by amino acids sequence.
What’s the difference between globular and fibrous? What is a fibril? How do you test for proteins?
Globular: Soluble e.g. haemoglobin, hormone, antibodies and enzymes.
Fibrous: Structural like keratin and collagen. This is insoluble.
Fibril is 3 polypeptide chains linked by disulfide bridges.
Test for proteins: Add biurette’s reagent to sample. Lilac/purple/violet colour change. Blue is negative. Positive is blue to purple colour change of solution.
What are enzymes? What is the structure of enzymes? How does this structure linked to active sites? Define activation energy.
Enzymes are globular proteins. Usually have tertiary structure, sometimes quarternary. Tertiary structure arises to different shaped active sites that can temporarily bond with complementary substrates. Tertiary structure gives speficially shaped active sites that are complementary to the substrate.
Activation energy: The minimum amount of energy required for a chemical reaction to begin.
Enzymes lower the activation energy.
What are the effects on the rate of enzyme of the following factors: enzyme concentration, substrate
concentration, concentration of competitive and of noncompetitive inhibitors, pH and temperature
Enzyme concentration: Increase enzyme concentration proportionally increases the rate of reaction (given that substrate conc. is in excess.)
Substrate concentration: A quicker initial rate of reaction. This is because substrate concentration is limiting factor. Then starts to level off - now enzyme concentration is limiting factor.
Adding fixed conc. of competitive inhibitor and increasing substrate conc.: Slower rate of reaction - higher chance competitive binds. As sub conc increases, rate inc. and will eventually level off at same rate - more likely substrate will bind with a.s. than inhib.
Adding a fixed conc of non-competitive inihibitor: Slower rate of reaction and levels off lower as enzymes denatrued as AS no longer complementory to substrate. Noncompetitive inhibitor bind to enzyme away from A.S.
pH: Different enzymes have different optimum pH. As pH gets closer to optimum, rate of reaction increases. As further away, drops as OH- and H+ interfere with h bonds of amino acids.
Temperature: Increasing will increase rate of reaction. Substrate more k.e. more likely chance of successful collisions. More enzyme substrate complexes formed, faster rate of reaction. Too high, ezymes start to denature - not immediate.
What are constitutes of triglycerides? What are constitutes of phospholipids? What type of bond is formed between the constitutes? Why are lipids hydrophobic?
Triglyceride = glycerol + 3x fatty acids.
Phospholipids = Glycerol, 2x fatty acids, phosphate
Ester -coo- bond forms between fatty acids and glycerol and 3x h2o removed.
Lipids are non-polar therefore hydrophobic.
What’s the test for proteins, lipids and reducing sugars and non-reducing sugars?
Proteins: Biurettes, blue to purple solution for positive.
Lipids: Add ethanol, add water, white emulsion indicates lipid presence
Reducing Sugar: Add benedicts, boil it/heat, brick red precipitate if reducing sugar.
Non-reducing sugar: Hydrolysis by boiling with dilute HCl. Neutralise with NaOH. Then benedicts again.
Structure of DNA? What are the 4 nitrogenous bases involved called? What’s the monomer and polymer? What type of bond forms between the phosphate group and deoxyribose?
- A DNA molecule is a double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs.
- Guanine, cytosine, thymine, adenine.
- Monomer = nucleotide - polymer = polynucleotide
- Phosphodiester bond
