Ch 5 - Pt 2 - Proteins Flashcards
(25 cards)
Enzyme
Proteins that serve as catalysts in living organisms; typically very large molecules that bring together/break apart substrates (the molecules upon which a chemical reaction occurs).
Catalyst
A substance that accelerates the rate if a chemical reaction without affecting the products of the reaction and without itself being altered or consumed by the reaction.
Amino acids
An organic molecule possessing both an amino acid and a carboxyl group.
The monomer building blocks of proteins.
Polypeptides
Polymers of amino acids
A protein consists of one or more polypeptides
Amino acid monomers
Organic molecules possessing both carboxyl and amino groups. Differ in their properties due to differing side chains (R-groups).
How many different amino acid monomers from which polypeptides are assembled?
20
Peptide bonds
The covalent bond between the carboxyl group of one amino acid and the amino group on another formed by a dehydration reaction.
The link between amino acids.
Dehydration reaction.
How are peptide bonds formed?
Through dehydration reactions.
How does a protein’s specific conformation/3D shape effect it’s function?
A protein’s specific conformation determines its function
What are some examples of models depicting a proteins specific conformation (3D shape)?
Space-filling model, ribbon model, 3D complementarity between an antibody protein and an invading virus particle
What are the 4 levels in protein structure?
Primary, secondary, tertiary, and (in some cases) quaternary structure
Primary structure of a protein
1) The linked series of amino acids with a unique sequence.
2) The 29 amino acids can be assembled into 20^127 sequences.
3) Primary structure dictates structure at higher levels.
Secondary structure of proteins
Hydrogen bonds between amino acids of a single polypeptide (a helix) or amino acids of adjacent polypeptides (B sheet) bring about secondary structure
Tertiary structure if proteins
1) Results from interactions between the side chains (R-groups) of amino acids
2) Involves a variety of bonds: disulfide bridges, hydrogen bonds, van der Waals interactions, ionic bonds
Quaternary structure of proteins
Are comprised of 1+ polypeptide subunits
Example of the importance of primary structure
Sickle-cell hemoglobin differs from normal hemoglobin in only one amino acid
Denaturation
Occurs when a protein unravels and loses its 3D confirmation
Ex: cooking meat, ceviche
Protein functions
Enzymes, structural proteins, storage proteins, transport proteins, hormones, receptor proteins, contractile and motor proteins, defensive proteins
Structural proteins
Keratin: structural protein in hair, nails, etc
Collagen: the most abundant protein in animals and provides the high tensile strength and resilience in skin, tendons, and ligaments
Storage proteins
Ovalbumin (albumin): egg white is 10% protein dissolved in water and serves as a source of nutrition for a developing embryo
Hormone (proteins)
Insulin: a protein hormone produced in the pancreas; regulates carbohydrate metabolism
Receptor proteins
Transmembrane receptor proteins can pump molecules against their diffusion gradient and are also involved in promoting and regulating chemical reactions in cells
Contractile and motor proteins
Dynein: the motor protein that moves material within the cell by “walking” along support structures in cells
Defensive proteins
Antibodies are protein signals and binding sites for components of the immune system.
(Ex: the venom of stingrays)
