Amino Acids in Biochemistry Quiz

Which of the following is NOT a function of amino acids in biochemistry?

• Building blocks for proteins

• Precursors of physiologically important N-containing compounds

• Main source of genetic information

• Fuel in metabolism

What is the general structure of a common amino acid?

• Amino group, carboxyl group, hydrogen atom, and R group bonded to a central alpha carbon

• Two amino groups, one carboxyl group, and a methyl group bonded to a central carbon

• Carboxyl group, phosphate group, and two R groups bonded to a central carbon

• Amino group, carboxyl group, and two hydrogen atoms bonded to a central carbon

Tags

NGSS.HS-LS1-6

At physiological pH (7.4), what is the state of the amino and carboxyl groups in an amino acid?

• Both are uncharged

• Amino group is protonated (NH3+), carboxyl group is dissociated (COO-)

• Both are protonated

• Amino group is dissociated (NH2), carboxyl group is protonated (COOH)

Tags

NGSS.HS-PS1-2

Which statement best describes the difference between L-forms and D-forms of amino acids?

• L-forms are found in bacterial cell walls, D-forms in mammalian proteins

• L-forms and D-forms are identical in structure and function

• L-forms are found in mammalian proteins, D-forms in bacterial cell walls

• D-forms are more common in nature than L-forms

Why are amino acids considered chiral molecules?

• They have two identical side chains

• The central alpha carbon is bonded to four different groups

• They contain a phosphate group

• They are always found in pairs

Which of the following is a correct application of the concept of isoelectric point (pI) in amino acids?

• The pI is the pH at which the amino acid has a net positive charge

• The pI is the pH at which the amino acid has a net negative charge

• The pI is the pH at which the amino acid has no net electric charge

• The pI is the pH at which the amino acid is most soluble in water

What is the general structure of an amino acid at physiological pH (around 7)?

• An amino group, a carboxyl group, a hydrogen atom, and an R group attached to a central carbon

• Two carboxyl groups and a methyl group attached to a central carbon

• A phosphate group, a hydroxyl group, and a hydrogen atom attached to a central carbon

• Two amino groups and a sulfur group attached to a central carbon

Which form of amino acids is found in mammals?

• D-form

• L-form

• Both D- and L-forms equally

• Only the D-form in cell walls

At what pH is an amino acid deprotonated if pKa < pH?

• Always

• Never

• When pH is less than pKa

• When pH is greater than pKa

Which amino acid is known for having a sweet smell and is branched?

• Glycine

• Valine

• Leucine

• Methionine