Topic 1 - Everything Can’t Understand Flashcards
Contrast saturated and unsaturated fatty acids
Saturated:
– Contain only single bonds
– Straight chain molecule have many contact points
– Higher melting points = solid at room temperature
– Found in animal fats
Unsaturated:
– Contains double carbon bonds
– Kinked molecule has a few contact points
– Lower melting point = liquid at room temperature
– Found in plant oils
Relate the function to the structure of triglycerides to their functions
High energy:mass ratio = high calorific value from oxidation.
Insoluble hydrocarbon chain = no effect on water potential of cells and used for waterproofing
Slow conductor of heat = thermal insulation
Less than the water = buoyancy of aquatic animals
State 4 biologically important properties of water
– Metabolite/solvent for chemical reactions in the body.
– High specific heat capacity
– High latent heat of vaporisation
– Cohesion between molecules
Explain why water is significant to living organisms
– Solvent for polar molecules during metabolic reactions
– Enables organisms to avoid fluctuations in core temperature
– Cohesion tension of water molecules in transpiration stream
Explain the role of hydrogen ions in the body
– Hydrogen ions help regulate pH in the body affecting enzyme activity and cellular processes.
Explain the role of iron ions in the body
– Iron bonds to porphrin to form haem group in haemoglobin.
– Haem group has binding site to transport molecules of oxygen around the body in the bloodstream.
Explain the role of sodium ions in the body
– Involved in co transport for absorption of glucose and amino acids in the lumen of the gut.
– Involved in propagation of action potentials in neurons
Explain the role of phosphate ions in the body
They are components of:
– DNA
– ATP
– NADP
– CAMP
What are the components of an amino acid?
Carboxyl group
Variable R group
Amine group
How do amino acids differ from one another in terms of structure?
The variable R group will be different
Define secondary structure of a protein
Folding or coiling of the polypeptide chain due to the hydrogen bonding between amino acids to form either an alpha helix or a beta pleated sheet.
Define tertiary structure of a protein
3-D structure formed by further folding of the polypeptide forms, disulphide bridges, ionic bonds and hydrogen bonds.
What are the structure and function of globular proteins?
Structure:
– Compact spherical and water soluble due to hydrophilic R groups on the outside.
– Have a tertiary structure stabilised by hydrogen bonds ionic bonds and disulphide bridges.
– Examples are enzymes, transport, proteins, hormones, and antibodies.
Describe the structure and function of fibrous proteins.
Structure:
– Long strong and insoluble due to hydrophobic R groups on the outside.
– Form fires with little to know tertiary structure, often with many cross-links for strength.
Function:
– Provides structural support and strength
– Examples is keratin collagen and elastin.
Outline how chromatography can be used to identify amino acids in a mixture.
- Use a capillary tube to spot mixture onto pencil origin line and place chromatography paper in solvent.
- Allow solvent to run until it almost touches the other end of the paper.
- Use revealing agent to see spots.
- Calculate Rf value.
What are enzymes?
- Biological catalysts
- Specific tertiary structure to determine shape of active site that is complementary to substrate.
- formation of enzyme substrate complex lowers activation energy of metabolic reactions
What is the allosteric site?
The region on an enzyme that causes a change in the enzymes shape an activity.
What is an enzyme in inhibitor?
Molecules that reduce the rate of enzyme controlled reactions by interfering with enzyme activity. There are two types competitive and non-competitive.
What is a competitive inhibitor?
The similar in shape to the substrate so they can compete with the substrate for the active site when the inhibitor is in the active site the real substrate cannot bind fewer enzyme substrate complexes formed.
What is a non-competitive inhibitor?
Different shape from the substrate instead of competing for the active site they attached to the allosteric site. Altering the shape of the active site of the substrate can no longer bind properly.
State the role of RNA in living cells
Messenger RNA – carries the genetic code from DNA in the nucleus to ribosomes for protein synthesis.
Transfer RNA – brings the correct acids to the ribosome based on the mRNA sequence.
Describe the structure of DNA
Double helix of two polynucleotide strands
Hydrogen bonds between complimentary purine and pyrimidine base pairs on opposite strands.
Relate the structure of DNA to its functions
– Sugar phosphate backbone and many hydrogen bonds provides stability
– Long molecules stores, lots of information
– Helix is compact for storage in nucleus
– base sequence of triplets codes for amino acids
– Double stranded for semi Conservative rep application
– Complimentary base pairing for accurate replication
– Hydrogen bonds break so strand separate for replication
Describe the structure of mRNA
– Long ribose polynucleotide
– Contains uracil instead of thymine
– single-stranded and linear
– codon sequence is complementary to exons of one gene from 1 DNA strand
Relate the structure of messenger RNA to its functions
– Breaks down quickly so no excess poly peptide forms
– Ribosomes can move along the strand and tRNA combined to exposed bases
– Can be translated into a specific polypeptide by ribosomes
What is the structure of tRNA?
– Anticodon loop: this is complimentary to the code on on the mRNA.
– Amino acid attachment site: specific amino acids can attach.
– Cloverleaf shape: due to hydrogen bonds between complementary bases forming stems and loops.
Outline the process of semiconservative DNA replication
- DNA helicase breaks down hydrogen bonds between base pairs.
- Each strand acts as a template.
- Free nucleotides attached to exposed complementary base pairs.
- DNA polymerase catalyses condensation reaction that joins adjacent nucleotides on new strand.
- Hydrogen bonds form.
How is ATP res synthesised in cells?
ATP synthase catalyses condensation reactions between ADP and Pi during photosynthesis and respiration.
Explain why ATP is suitable as the energy currency of cells
– High energy bonds between phosphate groups
– Small amounts of energy released at a time = less energy wasted as heat
– Single step hydrolysis = energy available quickly
– Readily synthesised
