Biochemical reactions Flashcards
Macromolecules
Macromolecules Monomers + functional groups Four types of macromolecules of interest to us: Carbohydrates Proteins Lipids Nucleic Acids
Carbohydrates
Monomer: simple sugar Ex. Glucose Functional group(s): Carboxyl Hydroxyl Polymer: complex CHO Starch, glycogen
Proteins
Monomer: amino acids 20 total, 9-10 essential Functional group(s): Carboxyl Amino Polymer Polypeptide Protein
Lipids
Monomer: Fatty acid Functional group(s): Carboxyl Polymers: many – depending on the type of lipid Phospholipid, triglyceride
Nucleic Acids
Monomer: nucleotide A, T (or U), C, G Functional group(s): Phosphate Amino Hydroxyl Polymer: DNA and RNA
Biochemical Reactions
Chemical reactions associated with biological processes
Often involve a combination of more than one type of reaction
Four main types of reactions:
Neutralization
Oxidation-Reduction
Condensation
Hydrolysis
Acid-Base Reactions
Acid: produces H+ ions in water
pH value less than 7
Base: produces OH- ions in water or accepts H+ ions
pH value more than 7
Neutralization Reaction: interaction of an acid and a base to form a salt (an ionic compound) and water
Neutralization Reaction
Necessary to maintain a constant pH state within the body
Buffers: resist changes in pH
Release H+ ions when fluid is too basic
Take up H+ ions when fluid is too acidic
Oxidation-Reduction Reactions
Involves the transfer of electrons
Oxidation: loss of electrons
Reduction: gain of electrons
Electrons are highly reactive and do not exist on their own in cells
If oxidation occurs to one molecule in the cell, reduction must immediately to another molecule
The entire reaction is often called a redox reaction
Oxidation-Reduction Reactions
Reduction Reaction: a gain of electrons.
Ex. O + 2e- O-2
Oxidation Reaction: a loss of electrons.
Ex. Mg Mg+2 + 2e-
Redox Reaction: An oxidation and a reduction reaction occur at the same time
Condensation Reactions
Involved in the assembly of all four types of macromolecules
An H atom is removed from a functional group on one molecule, and an OH group is removed from another molecule
Result: a larger molecule + water (water out, monomer in
Hydrolysis Reactions
Involved in the breakdown of macromolecules into their monomers
Water is added to break the bonds between monomers (water in, monomer out)
H from the water is added to one molecule, and the OH group is added to the adjacent monomer
Covalent bond between monomers breaks to form two smaller molecules
Role of Enzymes
An enzyme is a biological catalyst
Speeds up a biochemical reaction, but is not used up in the reaction
Enzymes are proteins
Have a specific shape
Each enzyme fits specifically with a substrate (the reactant for the reaction) to form an enzyme-substrate complex
Like a lock and key!
Enzyme-Catalyzed Reactions
Enzymes prepare substrates for reaction by changing the substrate, its environment, or both, in some way
Causing bonds to stretch or bend (making them more fragile)
Bring two substrates together
Transfer electrons to or from the substrate (i.e. reduce or oxidize it), making it less stable
Add or remove H+ ions to or from the substrate (i.e. act like an acid or base), destabilizing it
Enzyme Denaturation
Proteins are called denatured when they have lost their shape.
Caused by changes in temperature, pH, environmental factors, etc.
Because shape is so important to protein function, denatured proteins are no longer able to carry out their proper function
