Summary
Summary Cellular Respiration + Digestion APES1001 MBBCH I
- Course
- APES1001A (APES1001)
- Institution
- University Of The Witwatersrand (wits)
Summary of Cellular Respiration + Digestion lecture notes for APES1001 MBBCH I
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APES1001 Block 3 Malaaika Siddique Cellular Respiration + DigestionCELLULAR RESPIRATION,
METABOLISM + ENZYMES
,APES1001 Block 3 Malaaika Siddique Cellular Respiration + Digestion
Metabolism + Enzymes
Metabolism → sum of all chemical reactions within a cell
1. Catabolism → releases energy to breakdown complex molecules
2. Anabolism → consumes energy to synthesis of complex molecules
ENERGY – key component
Change in free energy (ΔG) → difference between free energy of final and initial states
Catabolic Anabolic
Exergonic – energy outwards (release Endergonic – energy inwards (consume
energy) energy)
Spontaneous = energetically favourable → Non-spontaneous = energetically
1. Products at lower energy unfavourable
2. Energy is released, not needed to 1. Because we require energy input
make products
ΔG is negative (-) ΔG is positive (+)
Energy is released Energy is consumed
Products are at a lower energy state than Products are at a higher energy state than
reactants reactants
Products < Reactants Products > Reactants
∴ Increases stability (entropy → degree of ∴ Decreases stability (entropy → degree
disorder) of system of disorder) of system
,APES1001 Block 3 Malaaika Siddique Cellular Respiration + Digestion
Hydrolysis of ATP
Adenosine triphosphate = Adenine nitrogenous base + ribose sugars + 3 phosphate groups
3rd phosphate has negative charge which makes molecule unstable as it forces joining of phosphate to other
phosphates → higher energy
When in contact with water, 3rd phosphate falls away forming →
Adenosine diphosphate (ADP) + Inorganic phosphate + Energy
ADP is at a much lower state of energy
Each ATP can hold 7.3 kcal of Energy per mole
ATP functions in powering cellular work
➔ By coupling exergonic with endergonic reactions
Chemical work: Hydrolysis of ATP into ADP is an exergonic reaction as it releases energy. This energy is
then used to push endergonic reaction to make complex molecules.
Transport work: Hydrolysis of ATP releases energy which helps pump potassium out of cells and sodium
into our cells. Active transport of cells across a membrane.
Mechanical work: Hydrolysis of ATP can allow for energy to be used to contract muscles and do work.
, APES1001 Block 3 Malaaika Siddique Cellular Respiration + Digestion
ATP is a renewable resource that can be regenerated by + phosphate to ADP.
Enzymes
Enzymes → biological catalyst that speeds up a reaction without being consumed by the reaction.
Enzymes are reaction-specific
Lock and key complex
Since enzymes are proteins, can
change shape.
When an enzyme changes shape to
better grasp substrate → induced
fit
Activation energy
Minimum energy required to start reaction / energy required to contort/bend the reactant molecule so that
bonds can break
Lower activation energy to speed up reaction. Enzymes help lower activation energy. Enzymes can only speed
up specific reaction depending on cell’s needs.
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