Quiz on Proteins

Proteins fold into specific 3D structures. Which property of amino acids contributes most directly to the tertiary structure of proteins?

• The linear sequence of peptide bonds

• The interactions among R groups of amino acids

• The hydrogen bonds between carboxyl and amino groups

• The presence of glycine at the N-terminus

A researcher replaces a polar amino acid in an enzyme’s active site with a nonpolar one. Which outcome is most likely?

• No change in enzyme activity

• The enzyme gains new catalytic properties

• The enzyme loses specificity for its substrate

• The enzyme becomes more resistant to denaturation

Which amino acid has a hydrophobic R chain?

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Which part of an amino acid determines its unique chemical properties?

• amino group

• carboxyl group

• hydrogen atom

• side chain

Which of the following is an essential amino acid in humans?

• glycine

• valine

• alanine

• serine

Which statement best explains why some amino acids are classified as essential?

• They are needed only during growth and development

• The human body cannot synthesize their carbon skeletons

• They are always more hydrophobic than non-essential amino acids

• They contain sulfur, which the body cannot produce

A patient’s diet lacks lysine but contains all non-essential amino acids. What is the most likely outcome?

• Protein synthesis continues normally

• Lysine will be synthesized from alanine

• Protein synthesis slows due to the missing essential amino acid

• Non-essential amino acids will convert into lysine

If hemoglobin is denatured, which body function is most directly impaired?

• Digestion of proteins

• Transport of oxygen to tissues

• Clotting of blood after injury

• Structural integrity of connective tissue

If actin filaments are disrupted in muscle tissue, what immediate effect would this have?

• Oxygen could not bind to hemoglobin

• Muscles would fail to contract properly

• Blood would clot too rapidly

• Enzymes could no longer catalyze digestion

Which scenario best illustrates proteins functioning as defensive molecules?

• Collagen forming strong tendons

• Antibodies binding to viral antigens

• Ferritin storing iron in the liver

• Insulin regulating glucose uptake