A level biochemistry and biological molecules

• The hydrophobic effect is the tendency of nonpolar groups to cluster together, away from water.
• Enzymes are made of amino acids, which have 22 types.
• Cyanobacteria can't photosynthesise very well and so they grow very slowly.
• The carboxylic acid group of an amino acid is acidic, while the amino group is alkaline.
• The R group of an amino acid can be all sorts of things, the simplest being hydrogen (Glycine).
• The R group of an amino acid is important for determining the characteristics of the amino acid.
• The primary structure of a protein is the chain of amino acids joined together.
• Dipeptide bonds are found in polysaccharides, while peptide bonds are found in polypeptides, and ester bonds are found in lipids.
• Secondary structure in proteins includes A Helices and B-Pleated sheets.
• The primary chain of a protein is usually folded into the alpha helix.
• Tertiary structure is the final 3D shape of a protein, held in place by hydrogen/ionic bonds and Van Der Waals forces.
• A change in the primary structure of a globular protein may result in a different 3-dimensional structure.
• Fibrous proteins, such as collagen, have structural functions, while globular proteins, such as enzymes and haemoglobin, carry out metabolic functions.
• Collagen's quaternary structure is made up of three polypeptide chains wound together in the same way as individual fibres are wound together in a rope, making them very strong and unlikely to break, meaning they can do a tendon's job of pulling a bone in the direction that a muscle contracts without breaking.
• The cross-linkages between the amino acids of polypeptide chains increase the strength and stability of a collagen fibre.
• Enzymes are biological catalysts that speed up reactions, have an active site, and can be denatured by high temperature or extremes of PH.
• Enzymes lower the activation energy of a reaction.
• Enzymes work through the Lock and Key hypothesis, where the active site with a complimentary shape to the substrate catalyses the reaction.
• Enzymes also work through the Induced Fit hypothesis, where the active site shape changes when the substrate binds.
• All the chemical energy released during respiration is not transferred to ATP, it is lost as heat.
• DNA is a code that encodes for amino acids, with three bases coding for an amino acid.
• DNA polymerase causes nucleotides to join to other nucleotides using a phosphodiester bond.
• ATP can’t cross the plasma membrane.
• DNA helicase is needed to break the H bonds.
• Cacti have evolved to have spikes instead of leaves which decreases their surface area and means that they lose less water through their stomata.
• DNA is Deoxyribonucleic acid (DNA), while RNA is Ribonucleic acid (RNA).
• DNA replication involves unwinding the DNA helix, lining up free DNA nucleotides alongside each ‘parent’ DNA strand, and forming new phosphodiester bonds between the phosphate of one nucleotide and the sugar of another.
• ATP provides a useful amount of energy for cellular processes.
• Nucleotides will join base to base by hydrogen bonds spontaneously (no enzyme required).
• Examples of uses of ATP include making macromolecules from smaller ones, muscle contraction, active transport, lysosome formation, and phosphorylation.
• The Meselson and Stahl experiment demonstrated that bases contain nitrogen, which can exist in isotopes called 14N and 15N (heavier).
• DNA unzips to code for a protein (RNA) and/or make a new strand of DNA to prepare for cell division.
• Generation 1 of the Meselson and Stahl experiment provides clear evidence that it isn't “conservative” (all old/all new), ruling out dispersive replication.
• Cells can make ATP (e.g from glucose).
• ATP stands for Adenosine triphosphate, a nucleotide (like DNA and RNA) that provides a little burst of energy.
• ATP can be called the ‘energy currency’ of the cell because it is like having coins which you can spend easily.
• ATP can be recycled through addition and removal of a phosphate.
• Alveoli in our lungs have a very high surface area to volume ratio allowing us to exchange more oxygen.
• The amino acids are joined together into a polypeptide and then folded into protein.
• DNA can be centrifuged in a ‘density solution’ and the DNA settles in the part of the test tube which matches the density of the DNA.