Enzymes in Biology Flashcards
the "biological catalysts" we all know and love... explored in detail!
What make enzymes usefull in Organisms?
- They can speed up rate of metabolic reactions, able to be re-used for future reactions
- Small amount can be used to catalyse reactions to form products, from reactions.
- Number of reactions enzyme can catalyse reactions per second = Turnover Number
What are Anabolic and Catabolic Reactions!
- ANABOLIC: Smaller molucles made into a larger molecule (ENDO)
- CATABOLIC: Larger molecules brocken down into smaller molecules (EXO)
What makes the shape of enzyme active site crucial?
- Tertiary structure of enzyme active site must be complamentary to shape of substrate, in order to successfully bind
- Therefore, each type of enzyme remains highly specific to its substrate, fitting active site
- Hence, changes to active site will significantly alter ability to catalyse reaction, affecting the bionds that hold protiens in place!
What are intracellular enzymes?
- These are enzymes working WITHIN the cell
- Participates in an enzyme cascade, where products become reactants of next reaction
- Both Anabolic and Catabolic reactions take place!
Explain and example of Intracellular Enzyme!
- CATALASE!!
- Fasterst acting enzyme, with turnovernumber of 6 million per second!
- Found in small vesicles (peroxisomes)
- Protects cell from damage by breaking down H202 (a toxic by-product of many metabolic reactions) into H20 and O2!
What are extracellular enzymes?
These are secreted to work in the bloodstream!
Explain examples of extracellular enzymes!
- AMYLASE: Secreted by salivary glands, to digest starch polysaccharides into disaccahide maltose!
- TRYPSIN: Secreted by pancreas, digesting polypeptides into amino acids (hydrolysing peptide bonds)
How can we describe basic Lock and Key model in basic steps?
- Enzyme + Substrate (approaches)
- Enzyme-Substrate Complex
- Enzyme-Product Complex
- Enzyme + Product (releases)
How does an enzyme catalyse a reaction?
- Reactants will need to collide with sufficient energy to undergo a successfull reaction
- Hence, enzyme active site will bring molecules closer together, providing a more accessibly reaction plane
- So, with enzymes, less energy required to collide and undertake a reaction, LOWERING ACTIVATION ENERGY!
What will lowering activation energy do for Reactants?
A greater proportion of molecules with sufficient energy to react upon collision (Boltzmann.D logic…)
How does the Induced Fit Model takem place?
- Substrate will approach enzyme, via own K.E.
- Active site will slighly be changed to fit around substrate, where R groups may be altered to precisly fit substrate
- Enzyme-Substrate Complex formed, where non-covalent forces will hold substrate in place.
- Reaction catalysed, substrate will diffuse away, active site returns to original shape!
What is a Cofactor?
- This is an Mineral Ion, INORGANIC substance that will TEMPORARILY BIND to enzyme’s allosteric site!
- This will temporarily change the active site’s shape, increasing the likelyhood of enzyme-substrate complexes to occur!
What is a Coenzyme?
- This are Viatmins, ORGANIC substances that will TEMPORARILY BIND to enzyme’s allosteric site!
- This will temporarily change the active site’s shape, increasing the likelyhood of enzyme-substrate complexes to occur!
What can Coenzymes and Cofactors do to a substrate?
They may add/remove electrons to a substrate to complamentary fit into active site even further!
What is an Apoenzyme and a Holoenzyme?
- APOENZYME = This is an inactive enzyme, which may need a coenzyme to become activated, allowing substrate binding to occur!
- HOLOENZYME = Entire complex of an activated enzyme, able to catalyse reactions
