Metabolism - extra Flashcards
Which amino acids are always protonated?
Arginine and lysine
Which amino acids are always negatively charged?
Glutamate and aspartate
What are the 6 hydrophilic side-chained amino acids?
Season Three’s Tyrion Acquired a Giant Cyst
Serine, Threonine, Tyrosine, Asparagine, Glutamine, Cysteine
Which group is normally on the right of the carbon in an amino acid?
The carboxyl group.
How can electrophoresis be used to measure changes in DNA sequences (mutations)?
A change in DNA (even small point mutations) will induce a slight change in charge which will effect the migration rate of the protein in electrophoresis, separating it from its un-mutated protein.
Which bonds are involved in tertiary structure of proteins?
- Hydrogen bonds
- Ionic interactions
- Hydrophobic interactions
- Disulphide bridges
What bonds stabilise alpha helices and beta-pleated sheets?
Hydrogen bonds
How are bonds distributed in alpha helices and beta-pleated sheets?
Alpha - between N-H and C=O every 4 amino acids apart
Beta - between N-H and C=O between two or more beta strands
What is Gibbs free energy?
The amount of energy within a molecule that is able to perform useful work at a constant temperature. If it is negative, the reaction is spontaneous. Measured in kJ/mol.
Why is ATP hydrolysis good for a coupled reaction?
ATP has phosphoanhydride bonds with a large negative Gibbs free energy value, meaning they are high energy bonds.
In respect to entropy, where will a spontaneous reaction proceed towards?
Towards products with a greater entropy.
What is Km?
The value of substrate at half maximum velocity (half of the active sites are occupied).
- Independent of substrate concentration
- Constant for an enzyme
- The smaller the Km, the higher the affinity of the substrate for the enzyme.
What is Vmax?
The maximum velocity of an enzyme at which all the active sites are occupied.
How do you calculate Km?
Km = 1/2(Vmax)
How is Km and Vmax affected by a competitive inhibitor?
Vmax is unchanged but Km is increased.
How is Km and Vmax affected by a non-competitive inhibitor?
Vmax is not met but Km is unchanged as the ability to bind is not altered, just some active sites are permanently ‘poisoned’.
How do vesicles move through cells?
Short distance - diffusion
Long distance - cytoskeleton-based motor proteins
What does NADH accept?
1 proton and 2 electrons
What is a coenzyme?
Binds to enzymes and assists in enzymatic activity. They are not specific to a certain enzyme but will only function after binding to an enzyme).
What is NADH important for?
Dehydrogenase reactions.
What are endosomes?
Membrane-bound organelles similar to temporary vesicles used for transportation.
What is the different between early, recycling and late endoscopes?
Early - involved in the sorting of ligands and receptors into different compartments.
Recycling - receive internalised material from early endoscopes and direct to cell surface or Golgi
Later - derived from vesicular parts of early endosomes and are tasked with managing receptors not suitable for recycling. Prepare them for lysosomal degradation by fusing with lysosomes.
How is a spectrophotometer used to measure enzyme activity?
Measures the amount of light absorbed by a substrate. Can measure the production of a substrate or the use up of a substrate but analysing changes in light absorption.
What is GTP used for?
Can be used as an energy source but mainly involved in cell signalling.
Another name for co-enzyme Q?
Ubiquinone
How many molecules of ATP do anaerobic and aerobic respiration produce?
Anaerobic - 2
Aerobic - 38
What does FADH2 donate?
2 electrons and 2 protons
What is ACAT?
An intracellular enzyme that works on cholesterol once it is taken up into a cell by endocytosis.
What differs between the different classes of lipoproteins?
Form of apoprotein found in them - allows recognition by different cell types.
What enzyme is used to catalyse the formation of cholesterol esters?
Lethicin cholesterol acyltransferase (LCAT)
How do resins/sequestrants work?
Bind to bile acid-cholesterol complexes and prevent their reabsorption into the small intestine, reducing LDL levels and increasing HDL levels.
What is the difference between glycolysis and gluconeogenesis?
Glycolysis takes place in cytoplasm and gluconeogenesis takes place in the liver specifically.
Gluconeogenesis also does not produce acetyl-coA or pyruvate.
How many ATP molecules are used in gluconeogenesis?
6
What does the R group of an amino acid change?
The chemical properties of the amino acid.
