USC Bridge 1.4 chemical reactions
Occur when chemical bonds are formed, rearranged, or broken.
Can be written as chemical equations
Chemical equations contain:
Reactants-substances entering into a reaction together
product- resulting chemical end products
amouunts of reactants and products are shown in balanced equations
Subscripts show how atoms are joined by bonds
Three main types of chemical reactions
When atoms or molecules combine to form a larger more complex molecule
Anabolic reactions: A+B-> AB
always Involves bond formation
ie: amino acids form a protein molecule
Bonds are broken in larger molecules, resulting in smaller less complex molecules or constituent atoms (reverse of synthesis reactions).
Involve catabolic (bond breaking) reactions AB-> A+B
glycogen is broken down to release glucose molecules. Fats are digested in the small intestine by decomposition reactions..
Exchange reactions ( displacement reactions)
Bonds are both made and broken, involves synthesis and decomposition.
Parts of the reactant molecules change partners producing different product molecules
ATP transfers phosphate group to glucose to form glucose-phosphate
Oxidation reduction (redox) reactions
The gain of oxygen or loss of hydrogen atoms and their electrons.
- Oxidized substances lose electrons and energy (electron donor)
- reduced substances gain electrons and energy (electron acceptor)
different from ionic bonds bonds as electrons are lost entirely
Reactions that release energy
- products have less potential energy than reactants
- catabolic and oxidative reactions ie breaking down a large molecule into smaller ones gives off energy
Energy absorbing reactions that contain more potential energy in their chemical bonds than did the reactants
- products have more potential energy than reactants
- anabolic reactions
Reversibility of chemical reactions
All chemical reactions are theoretically reversible.
- Chemical equilibrium occurs if neither a forward nor a reverse reaction is dominant
- many biological reactions are not very reversible because energy requirements to go backward are too high or products have been removed
Rate of chemical reactions are affected by:
Increase the rate of a reaction without being chemically changed or becoming part of the product
Biological catalysts. Separate proteins that help a reaction. Not part of the reaction and not changed during the reaction
In a chemical reaction _______ join to form _____
What will be the effect on a chemical reaction if the concentration of reactants is increased?
The speed of the reaction will increase
Building muscle tissue is an example of: