Unit 4 - Enzymes and energy

Effect of temp. and PH on protein structure

Effect of temp. and PH on protein structure

Denaturing = When the protein is not able to work to its fullest potential or at all due to the conditions in which it is. The protein works best in its optimal conditions in temp, PH, etc.

Break down large molecules

catabolic reactions = hydrolysis

Build up of molecules from monomers

Anabolic = condensation reaction

How does metabolism occur?

Collision theory = a chemical reaction can only occur between particles when they collide

Steps of enzyme reaction

1. The surface of the substrate make contact with the active site of an enzyme

2. The enzyme and substrate change shape to provide a fit (induced - fit binding)

3. A temporary complex called the enzyme-substrate complex forms

4. Activation energy is lowered, and the substrate is altered by the rearagement of the existing atoms

5. The transformed substrate, the product, is released from the active site

6. Enzyme returns to original shape

Activation energy

Required to destabilise chemical bonds

Exergonic

More energy is released when the chemical bonds form than is needed to break the bends

Endergonic

More energy is needed to break the bonds than is released when the products form

Factors affecting rate of enzyme catalyse reaction

1. PH

2. Temperature

3. Substrate concentration

4. Enzyme inhibitors

Cell respiration

The process by which organisms use oxygen to break down food molecules to get chemical energy for cell functions

Where is energy stored that is made from cellular respiration?

ATP

Aerobic respiration

Oxygen must be present at the end of the ETC. Net gain of 30-34 ATP. If O2 is not available, products will be different

Anaerobic respiration

Doesn’t require oxygen but glucose. Net gain of 2 ATP

Metabolism

Chemical reactions which occur within a living organism

Forms of enzyme - catalysed chemical reactions

Chain / linear pathway and cyclical metabolic pathway, eg: Krebs cycle

Equation for aerobic cellular respiration

C6 H12 O6 —> 6CO2 + 6H2O + ATP

Intermediet step

• The pyruvate is transported into the mitochondrial matrix by active transport

• There the pyruvate is oxidised to CoA

• CO2 is released and 2 NADH are produced

• CO2

• Aerobic

Krebs cycle (citric acid cycle)

• Aerobic process

• CO2 is released

• 2 ATP, 6 NADH, 2 FADH2 are produced

The electron transport chain

• Involving inner mitochondrial membrane

• Aerobic

• ECM goes to enzymes and drop off electrons

• Enzyme gets energy to pump the proton across = NADH = NAD+ - H+, water gets produced

• H+ flows trough another enzyme back and binds to ADP which becomes ATP

Properties of ATP

• Soluble

• Forms hydrogen bonds

• Third phosphate group

• Small energy release

• Stability

• Cant pass membrane freely

Glycolysis

• Need 2 ATP to start reaction = net yeld 2 atp.

• In the cytoplasm

• Anaerobic

• Glucose is converted to 2 pyruvate

• 2 NADH are produced

• Yeast can break down to CO2 + ethanol = fermentation, pyruvate becomes lactic acid = lactic acid fermentation.

Steps of Krebs cycle

1. CoA + oxaloacetate = 6 carbon molecule

2. Turns into 5 carbon molecule when NAD+ takes a carbon as CO2

3. 4 carbon molecule due to the same step as 2

4. GDP is generated

5. FADH —> QH2

6. NADH —> NAD

7. Repeat

O.I.L

Oxidation is loss of electrons

• NAD+ picks up a hydrogen and becomes “reduced NAD”

R.I.G

Reduction is gain of electrons

• NADH loses an hydrogen and becomes NAD-. The hydrogen can reduce a molecule this enzyme catalyses reaction

Calvin cycle

The reactions of photosynthesis that use the energy stored by the light-dependent reactions to form glucose and other carbohydrate molecules

Steps of the Calvin cycle

1. 3 CO2 adds carbon to 5 carbon molecule

2. 6 carbon molecule

3. Splits into two (3 carbon molecule)

4. 6 ATP and ADP are made

5. 6 NADPH and ANDP+ are made

6. 1 3 carbon molecules goes to make glucose

7. 5 3 carbon molecules get recycled

8. 3 ATP and ADP

9. 3 RuBP (5 carbon molecules)

10. Repeat

Feedback inhibition

• To prevent over production of certain substrate

• When there is sufficient amount of product it binds to the allosteric site in the first step of the pathway

• Reactivates enzyme when more product is needed

Mechanism-based inhibition concequence

Irreversible binding of a inhibitor

Extracellular enzymes

Synthesised inside the cell and then secreted outside the cell

Intercellular enzymes

Catalyse reactions within the cell