Lecture on Amino Acids, Peptides, and Proteins

These flashcards cover key concepts related to amino acids, peptides, and proteins to aid in exam preparation.

What are the building blocks of proteins?

Amino acids (AA)

How many different amino acids are commonly found?

20 different amino acids.

What is a dimer in the context of amino acids?

A dimer is formed when two amino acids are linked together.

What term describes a polymer made of amino acids?

Polyamino acid.

What is a zwitterion?

A molecule that has both charged sites but is overall electrically neutral.

What is the characteristic of non-polar aliphatic R groups?

They have hydrophobic characteristics.

Which amino acid was the first to be discovered?

Asparagine in 1806.

Name one amino acid with a positively charged R group.

Lysine.

What are peptide bonds formed by?

Dehydration synthesis between amino acids.

How do amino acids behave at physiological pH?

They exist as zwitterions.

What type of groups do aromatic amino acids have?

Aromatic R groups.

What is the pKa of glycine?

pKa ~ 2.34 and 9.60.

What defines an oligopeptide?

A peptide chain consisting of 2-20 amino acids.

What is the average weight of an amino acid residue?

Approximately 110 Daltons.

What structural feature do all amino acids except Glycine have?

A chiral center.

What is an enantiomer?

Non-superimposable mirror images of a molecule.

What does it mean for an amino acid to be hydrophobic?

It avoids contact with water and is non-polar.

How is electrophoresis used in protein study?

It separates molecules based on their charge and size in an electric field.

What charge do most proteins have at a pH above their isoelectric point?

Negative charge.

What is SDS-PAGE?

A method that separates proteins based on their molecular weight.

What role does the R group play in amino acids?

It defines the properties and classification of the amino acid.

Define the term 'hydropathy index'.

A scale that indicates the hydrophobic or hydrophilic character of an amino acid.

What is the C-terminus of a peptide?

The end of a peptide chain with a free carboxyl group.

What is the primary structure of a protein?

The amino acid sequence of the polypeptide chain.

What does the term secondary structure refer to?

The local folding of a polypeptide into alpha-helices or beta-sheets.

How is a protein defined?

A macromolecule made of one or more polypeptide chains.

What type of bond forms between the amino group of one amino acid and the carboxyl group of another?

A peptide bond.

What is meant by a protein's isoelectric point (pI)?

The pH at which the protein has no net electrical charge.

Name one biochemical method for purifying amino acids or proteins.

Chromatography.

Explain the significance of chiral centers in amino acids.

Chirality affects the behavior and function of amino acids in biological systems.

How does lysine differ from aspartic acid in terms of charge?

Lysine has a positive charge, while aspartic acid has a negative charge.

What is the function of antibodic in protein separation methods?

To selectively bind to specific proteins of interest.