Enzymes Flashcards

Flashcards about Enzymes

In catalysis, enzymes ___.

Act as highly specific biological catalysts in the breakdown or assimilation of substances, speeding up the rate of metabolic reactions.

In regulation, enzymes __.

Provide a mechanism for regulating chemical reactions.

Most enzymes are __.

Globular proteins, consisting of one or more polypeptides coiled and folded together to form a globular structure

Rate of enzymatic reactions are affected by __.

Rate of enzymatic reactions are affected by pH, temperature, enzyme concentration and substrate concentration.

An example of an enzyme with absolute specificity is ___.

Sucrase catalyses only the breakdown of sucrose

An example of an enzyme with group specificity is ___.

Trypsin digests the peptide bond at carboxyl side of lysine or arginine in any polypeptide.

The active site is __.

The catalytic centre of the enzyme, where the substrate binds for catalysis to take place.

There are 4 types of amino acid residues in an enzyme:, , , and _.

Binding residues, catalytic residues, structural residues, and non-essential residues.

Activation energy is __.

The energy barrier that substrate molecules must gain before chemical changes are possible

The activation energy barrier can be overcome by __.

Increasing the free energy of the substrate or the addition of an enzyme/catalyst.

Proximity effect is when __.

Temporary binding of substrates next to each other on an enzyme increases the chance of a reaction.

Strain effect is when __.

Slight distortion of the substrates as they bind to the enzyme causes bonds of the substrate to be strained, thereby increases the chance of breakage.

The lock and key hypothesis suggests that __.

The enzyme and substrate are exactly complementary.

The induced fit model suggests that __.

When the substrate binds with the active site of an enzyme, it induces a 3D conformational change in the enzyme structure.

There are 3 main types of co-factors: ___.

Inorganic ions, co-enzymes, and prosthetic groups.

Cofactors are required for enzyme activity, but they are not catalytic on their own and __.

They are usually smaller than the enzyme that they are associated with, and are only required in small amounts.

Q10 = __.

Rate of reaction at x°C divided by Rate of reaction at (x +10) °C

pH affects enzyme activity in 2 ways: __.

Ionisation of the binding and catalytic residues at active site or change in 3D conformation of active site.

Reversible inhibitors __.

Do not permanently affect the enzyme.

Irreversible inhibitors __.

Bind to enzymes permanently.

A competitive inhibitor __.

Bears structural resemblance to the substrate molecule and is complementary to the specific 3D conformation of the active site, therefore, competing for binding at the same active site.

A non-competitive inhibitor __.

Bears no structural similarity to the substrate molecule.

Cells control enzymatic reactions through __.

Membrane compartmentalisation, variation in pH, controlling the concentration of substrates available and using regulatory enzymes and feedback control.

Negative Feedback is when __.

The output is used to inhibit the system.