Biochemistry. Lecture 1: Amino acids and proteins

From what are derived amino acids?

• Inorganic acids

• Organic acids in which the hydrogen atom is substitued by the carboxyl group

• Organic acids in which the hydrogen atom is substitued by the amino group.

• Organic acids in which the hydrogen atom is substitued by the aldehyde group

Proline and hydroxyproline are amino acids?

• Yes

• Yes, because of its amino group

• No, are imino acids

• No, are proteins

How many amino acids exist? How many of them are present in almost all proteins?

• 300, 20.

• 200, 30.

• 300,10

• 200, 20

What happens at physiological pH (7,4)?

• Most of the carboxyl groups are dissociated and most of the amino groups bind O2

• Most of the carboxyl groups are dissociated

• Most of the carboxyl groups are dissociated create anion NH3-

• Most of the carboxyl groups are dissociated, create anion COO- and most of the amino groups bind H+ creating cation -NH3+

Which is the dominant form of an amino acid?

• zwitteria

• zwitterion

• zwitter

• zwaer

What are amino acids?

• Amphotherics

• Amphophilics

What is the isoelectric point?

• The pH in which the amino acid is a zwitterion ion a

• The resultant electrostatic charge is equal to 0

• The pH in which the amino acid is a zwitterion ion and the resultant electrostatic charge is equal to 0

• The pH in which the amino acid is a zwitterion ion and the resultant electrostatic charge is equal to 5

Examples of amino acids with polar chains without charge.

• Cysteine

• Serine

• Tyrosine

• All the anteriors

Examples of amino acids with nonpolar chains

• Alanine

• Valine

• Leucine

• All the anteriors

Amino acids with basic side chains.

• Lysine

• Arginine

• Histidine

• All the anteriors