Introduction to Proteins Flashcards
pH =
-log [H+]
[H+] = 10^(-pH)
pH is the measure of the amount of _________ in a solution
hydrogen ions
Amino acids each contain a central carbon surrounded by what four things?
- a carboxyl group (C=O)
- an amino group (N-)
- a hydrogen atom
- an R group (as simple as H, or C chains)
What are the two functional groups of amino acids?
the carboxyl group and amino group
The side group, R group are divided into what four types of side chains?
polar, nonpolar, acidic, and basic
Aspartate and Glutamate are classified as: polar, nonpolar, acidic, or basic?
acidic
Arginine, Histidine, and Lysine are classified as: polar, nonpolar, acidic, or basic?
Basic
Asparagine, Cysteine, Glutamine, Serine, Threonine, and Tyrosine are classified as: polar, nonpolar, acidic, or basic?
Polar
The sequence of amino acids makes up what structure of a protein?
primary
Are nonpolar substances hydrophobic or hydrophilic?
Hydrophobic
Are polar substances hydrophobic or hydrophilic?
Hydrophilic
Define amphiphilic
Substances that are both polar and nonpolar
The secondary structure of proteins is described as what?
The initial folding of the amino acid chain (polypeptide)
What are the two structures an amino acid chain can fold into?
This would be secondary protein structure; amino acid chains can fold into ALPHA-HELICES or BETA SHEETS (pleated).
Alpha helices twist and form due to what bond?
Hydrogen bonding between carbonyl and mide groups.
Why is proline not found in the alpha helix?
Because the nitrogen of proline is bound to two carbons and has a limited ability to rotate.
In an alpha helix, where do the side chains, carbonyl groups, and amide groups face?
Carbonyl and amide groups face towards the inside of the helix. Side chains face the outside.
In beta pleated sheets, hydrogen bonding also occurs between the carbonyl and amide groups, but the ________ are stretched out and bonding occurs along the _______ of the chain.
In beta pleated sheets, hydrogen bonding also occurs between the carbonyl and amide groups, but the POLYPEPTIDES are stretched out and bonding occurs along the LENGTH of the chain.
Define tertiary structure of proteins.
Remember, primary is the lining up of the amino acids, secondary is the initial folding of the amino acid chain.
Tertiary structure is how the protein (either in alpha helix or beta pleated sheet form) further folds in on itself. It does this to hide the hydrophobic regions and expose hydrophilic ones.
In regards to protein structure, which structure functions to hide the hydrophobic regions and expose the hydrophilic ones?
Tertiary structure
Quaternary structure involves the interaction of multiple proteins. What are some possible ways these proteins are held together?
- hydrogen bonding
- disulfide bridges
- salt bridges
- hydrophobic forces
Note that not all proteins have a quaternary structure (Hemoglobin does, Myoglobin does not)
What are cofactors?
Cofactors are elements (organic or inorganic) that help an enzyme to catalyze a reaction.
They are necessary for the enzyme to perform its job.
What are two types of cofactors?
Coenzymes and Prosthetic Groups
How do coenzymes (a type of cofactor) work?
Coenzymes work with the enzyme, but are not covalently attached, to catalyze a reaction
How do prosthetic groups (a type of cofactor) work?
Prosthetic groups are covalently bonded to an enzyme.
What are isoenzymes?
Isoenzymes are enzymes that catalyze the same reaction, but they have a different physical and chemical pathway for doing so. They may be found in different parts of the cell or in different tissues.
