Protein Structure and Function

These flashcards cover key concepts related to protein structure and function from the lecture notes.

What are the main components of an amino acid?

Amino acids are composed of a central carbon atom bonded to a hydrogen atom, an amino functional group, a carboxyl functional group, and a variable R group.

What is the significance of the R group in amino acids?

The R group, or side chain, makes each of the 20 amino acids unique and determines their chemical properties.

How do amino acids interact in water?

In water, amino and carboxyl groups ionize, helping amino acids to stay in solution and affecting their reactivity.

What are the three general types of amino acid R-groups?

The R-groups can be classified as charged, uncharged polar, and nonpolar.

What happens when an amino acid's side chain has a negative charge?

It indicates the amino acid is acidic as it has lost a proton.

What is a peptide bond?

A peptide bond is a covalent bond that forms between the carboxyl group of one amino acid and the amino group of another.

What defines the N-terminus and C-terminus of a protein?

The N-terminus is the end with the free amino group, while the C-terminus is the end with the free carboxyl group.

What is the primary structure of a protein?

The primary structure is the unique sequence of amino acids in a protein.

What is a polypeptide?

A polypeptide is a chain of more than 50 amino acids.

What role do hydrogen bonds play in protein secondary structure?

Hydrogen bonds form between the carbonyl group of one amino acid and the amino group of another, contributing to structures like alpha-helixes and beta-pleated sheets.

What is tertiary structure in proteins?

Tertiary structure results from R-group interactions and leads to the distinctive three-dimensional shape of a polypeptide.

What are four types of R-group interactions in tertiary structure?

Hydrogen bonding, hydrophobic interactions, van der Waals interactions, and ionic bonding.

What is a quaternary structure of a protein?

Quaternary structure is formed by the bonding of two or more polypeptide subunits.

What are dimers in the context of protein structure?

Dimers are proteins that consist of two polypeptide subunits.

What is the importance of molecular chaperones in proteins?

Molecular chaperones facilitate protein folding and block inappropriate interactions between unfolded proteins.

What can happen if a protein misfolds?

Misfolded proteins can be infectious, causing other proteins to fold incorrectly, as seen with prions.

What are some functions of proteins in cells?

Proteins are involved in catalysis, structure, movement, signaling, transport, and defense.

Why are enzymes effective catalysts?

Enzymes hold substrates in precise orientation, which makes chemical reactions more likely to occur.

What is an active site in an enzyme?

The active site is a specific location on the enzyme where substrates bind and react.

What is denaturation in proteins?

Denaturation is the process where a protein loses its functional shape and cannot perform its normal function.