Energy & Metabolism 1 Flashcards
What is a chemical reaction?
occurs whenever chemical bonds are formed, re-arranged or broken, & when molecules are changed converted to different kinds of molecules
Reactions can be…
- exothermic
- endothermic
- reversible
- irreversible
What is an exothermic reaction?
- energy is held in bonds of reactants is greater than energy of products
- excess energy is released as heat or ATP
- seen in catabolic reactions
What is an endothermic reaction?
- energy contained in products is greater than energy of reactants
- requires energy to drive the overall reaction
- often seen in anabolic or synthesis reactions
What is a reversible reaction?
- can go in either direction, reaches equilibrium
What is an irreversible reaction?
- reactions only go in one direction
- often seen in exothermic reactions
What is a decomposition reaction?
- when large molecules are broken down into smaller ones
AB = A+B
What are hydrolysis (digestion) reactions?
- reactions where water is involved
- eg: digestion of glycogen to glucose
What are synthesis (combination) reactions?
where larger molecules are constructed from smaller units
A+B = AB
What are exchange/displacement reactions?
- parts of the reactants ‘change partners’
- AB+C = AC+B
What are oxidation - reduction ‘redox’ reactions?
oxidation: loss of an electron
reduction: gain of an electron
- oxidation & reduction always occur together
How do chemical reactions occur?
when chemicals (reactants) collide with enough energy to break bonds = activation energy
Define nature of reactants?
- simpler substance react more quickly
- smaller particles move more quickly and are likely to collide
- more complex molecules, requiring more activation energy
Define concentration of reactants
- higher concentration - more reactant molecules - more likely to collide
Describe how temperature can affect rate of reactions
warm temperature increases particle movement = more collisions
