biology C1.1

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define catalyst

substance that speeds up a chemical reaction without being consumed or permanently changed

what is the role of enzymes in chemical reactions of life?

Enzymes act as biological catalysts that speed up biochemical reactions essential for life.

Do enzymes get altered in reactions?

no

define metabolism

sum of all chemical reactions occurring within an organism

define enzyme specificity

each enzyme binds only to a particular substrate due to the complementary shape and chemical properties of its active site

how do enzymes regulate metabolism?

they control metabolic pathways by catalyzing specific steps, being activated, and ensuring reactions occur at required rates

what is an anabolic reaction?

builds complex molecules from simpler ones (requires energy).

what is a catabolic reaction?

breaks down complex molecules into simpler ones (releases energy).

examples of anabolic processes

protein synthesis

DNA replication

photsyntehsis

examples of catabolic processes

cellular respiration

digestion of starch

breakdown of lipids

properties of globular proteins

water-soluble

folded into spherical shapes

hydrophobic core

hydrophillic exterior

functional proteins

relationship between enzyme structure and specificity

3D structure determines the shape of the active site, which is specific to a substrate and ensures only certain molecules can bind.

describe the active site

region on an enzyme where the substrate binds and the reaction is catalyzed

what are the stages of enzyme catalyssis

1. substrate binds to active site

2. enzyme-substrate complex forms

3. reaction occurs

4. products release

5. enzyme unchanged

describe the induced fit model

Binding of the substrate induces a slight conformational chan

Role of random collisions in enzyme action.

Substrates collide with the active site due to random molecular motion; successful collisions result in binding.

enzyme-substrate movement in cytoplasm

Both enzyme and substrate move freely; many collisions.

enzyme-substrate movement in large substrates

Enzyme moves to substrate; limited mobility.

enzyme-substrate movement in immobilised enzymes

Substrate moves; enzyme fixed in place.

variation in enzyme specificity

Some enzymes are highly specific (one substrate), others act on groups of similar substrates.

define denaturation

Loss of an enzyme’s structure due to heat or pH changes, causing loss of function.

causes and effects of denaturation

causes: extreme heat, extreme pH

effects: active site changes shape —> substrate no longer bings —> activity stops

effect of temperature on enzyme activity

Increased temperature increases collisions until optimum; above optimum causes denaturation.

effect of pH on enzyme activity

Enzymes have an optimum pH; deviations disrupt ionic bonds → altered active site → lowered activity.

effect of substrate concentration

Increases activity until saturation; after that, rate plateaus.

ways to measure enzyme reaction rate

measuring substrate disappearance

product formation

investigative techniques for enzyme activity

measuring oxzgen production

colour change with indicators

pH changes

define activation energy

minimum energy required to start a chemical reaction

activation energy use

used to break or weaken substrate bonds

how do enzymes affect activation energy

Enzymes lower activation energy by stabilizing the transition state.