Proteins and Enzymes Flashcards
Polar covalent bond
electrons are drawn to one nucleus more than the other because on atom has a greater electronegativity
Ionic bond
when one atom is so electronegative that it removes an electron from another atom to form an ionic bond
isomer
molecules with the same chemical formula but atoms are arranged differently
Structural isomer
differ in how their atoms are joined together
Optical isomer
occur when a carbon atom has four different atoms or groups of atoms attached to it
- result from asymmetrical carbons
function of genetic regulatory proteins
regulate when, how, and to what extent a gene is expressed
structure of amino acid
- Carbon
- Amino group (H3N+)
- Hydrogen
- Carboxyl group (COO-)
What two isometric forms exist in amino acids
D- amino acids (dextrose, right)
L- amino acids (levy, left) - found in organisms
Three amino acids with special functions
Methionine
Proline
Cysteine
Methionine amino acid
initiates chains of amino acids
Proline amino acid
causes kinks in chains of amino acids
Cysteine
links amino acid chains together
Disulphide bridges
-SH group of cysteine react with another to form disulphides bridges
- common in extracellular proteins
= they will receive more stresses outside of the cells
How do amino acids bond together
condensation reaction
What link is produced by condensation reaction
peptide linkages
Primary structure
sequence of amino acids
Secondary structure
a helix
b pleated sheet
Tertiary structure
folding results in macromolecule with specific three dimensional shape
- outer surface present functional groups that can interact with other molecules
How is tertiary structure determined
Interactions of R groups
- Disulphide bridges
- Hydrogen bonds
- Aggregation of hydrophobic side chains
- van der Waals forces
- ionic bonds
Quaternary structure
interactions of subunits by hydrophobic interactions, van Der Waals, ionic and hydrogen bonds
How is specificity determined
shape and chemistry
Conditions that affect secondary and tertiary structure
- High temp
- pH changes
- High conc of polar molecules
- Nonpolar substances
Two forms of energy
Potential - stored
Kinetic - movement
Anabolic reactions
molecules made from simple molecules
- energy required
Catabolic reactions
molecules are broken down and energy is released
First law of thermodynamics
energy is neither created or destroyed
Second law of thermodynamics
energy is converted from one form to another, some of that energy becomes unavailable
What is entropy
a measure of the disorder in a system
ΔG = ΔH – TΔS
if ΔG is neg = energy released
if ΔG is pos = energy consumed
What is an exergonic reaction
releases free energy (catabolic)
- complexity decreases
What is an Endergonic reaction
Consume free energy (anabolic)
- complexity increases
At chemical equilibrium
ΔG = 0
how is ΔG related to equilibrium
the further towards completion the point of equilibrium is, the more free energy is released
What mechanisms would an enzyme use to catalyse a reaction
- orientation
- physical strain
- chemical strain
Induced fit
enzymes change shape when they bind to the substrate
