B1.2 Proteins Flashcards
What are proteins composed of?
Proteins are polymers made of monomers called amino acids
How many amino acids are commonly found in proteins?
There are 20 naturally occurring amino acids in proteins
What type of bond links amino acids together
Amino acids are linked by peptide bonds formed through condensation reactions
What is a dipeptide?
A molecule consisting of two amino acids joined by a peptide bond
What is a polypeptide?
A chain of three or more amino acids linked by peptide bonds
What determines the diversity of proteins?
The sequence, number, and type of amino acids in polypeptide chains
How does the genetic code influence protein variety?
The DNA base sequence dictates the order of amino acids, leading to a vast array of possible polypeptides
Approximately how many different polypeptides can be formed from 20 amino acids?
For a polypeptide chain of 50 amino acids, there are 20⁵⁰ possible combinations, equation to approximately 1.13 x 10⁶⁵ variation
What roles do proteins play in organisms?
Proteins function as enzymes, structural components, transport molecules, hormones and antibodies, among other roles
What is denaturation in proteins?
A process where a protein loses its 3D structure due to external factors like pH or temperature changes, leading to loss of function
How does pH affect protein structure?
Changes in pH can alter the ionisation of amino acid side chains, disrupting ionic and hydrogen bonds, causing denaturation
How does temperature affect protein structure?
Elevated temperatures can increase kinetic energy, leading to the disruption of hydrogen bonds and hydrophobic interactions, resulting in denaturation
Are all proteins equally sensitive to pH and temperature changes?
No, the sensitivity varies depending on the protein’s structure and function
What is the general structure of an amino acid?
An amino acid consists of a central (alpha) carbon atom bondend to an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and an R group (side chain)
What determines the properties of an amino acid?
The R group (side chain) determines the amino acid’s characteristics, such as being polar, non-polar, acidic or basic
How do amino acids differ from each other?
Differences in the R group lead to variations in size, charge, polarity and reactivity among amino acids
What is a zwitterion?
An amino acid molecule that has both a positive and a negative charge but is overall electrically neutral, commonly occurring at physiological pH
What are the four levels of protein structure?
Primary, secondary, tertiary and quaternary structures
What defines the primary structure of a protein?
The sequence of amino acids in a polypeptide chain
What are common types of secondary protein structures?
Alpha-helix and beta-pleated sheet, stabilised by hydrogen bonds
What interactions stabilise tertiary protein structure?
Hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions between R groups
What is quaternary protein structure?
The assembly of multiple polypeptide chains into a functional protein complex
What are globular proteins?
Spherical, water-soluble proteins that function as enzymes, transporter or regulators
What are fibrous proteins?
Long, insoluble, structural proteins that provide support and strength to tissues
