Amino Acids and Their Properties

This video tutorial covers the basics of amino acids, their structure, and types, including nonpolar, polar, acidic, basic, and aromatic amino acids. It explains how amino acids form peptide bonds through dehydration synthesis and discusses the ionization states of amino acids at different pH levels, focusing on the concept of zwitterions and pKa values.

What is the primary structural feature that makes a carbon atom chiral in an amino acid?

• Presence of a double bond

• Four different groups attached

• Two identical groups attached

• A single hydrogen atom

Which type of amino acid is characterized by an R group that is nonpolar?

• Acidic amino acid

• Polar amino acid

• Basic amino acid

• Nonpolar amino acid

Which amino acid is known for having an aromatic ring in its structure?

• Serine

• Valine

• Lysine

• Phenylalanine

Which amino acid is classified as basic due to its amine group?

• Valine

• Lysine

• Serine

• Aspartic acid

What type of reaction leads to the formation of a peptide bond between amino acids?

• Reduction

• Hydrolysis

• Dehydration synthesis

• Oxidation

What is the pKa value of the carboxylic acid group in alanine?

• 2.3

• 9.7

• 7.4

• 5.0

At a pH of 5, what is the net charge of alanine?

• +1

• 0

• -1

• +2

What is the term for an amino acid that has both a positive and a negative charge but is overall neutral?

• Anion

• Cation

• Zwitterion

• Ionized form

What happens to the amino group of alanine when the pH is above 9.7?

• It becomes neutral

• It becomes positively charged

• It loses a hydrogen

• It gains a hydrogen

How does the ratio between the protonated and deprotonated forms of an amino acid change with each unit change in pH?

• By a factor of 20

• By a factor of 2

• By a factor of 5

• By a factor of 10