IB Proteins

What structure mediates and controls the formation of polypeptides?

• ribosome

• nucleus

• mitochondria

• golgi apparatus

Condensation between two amino acids results in a _________, joined by a _________ bond.

• dipeptide, peptide

• dipeptide, ester

• disaccharide, peptide

• disaccharide, ester

Water is _______ in a condensation reaction.

• produced

• consumed

When forming a dipeptide, condensation occurs between the ______ from a carboxyl group on one amino acid and ______ from an amine group of another amino acid.

• OH, H

• H, OH

How many amino acids are naturally occurring (synthesized by ribosomes)?

• 19

• 20

• 21

• 22

Which is NOT a key idea that explains the huge range of possible polypeptides?

• They could be any length.

• There are 20 amino acid possibilities.

• The amino acids could be in any order or combination.

• Prokaryotes only use 10 amino acids.

If a polypeptide contains just 4 amino acids, calculate how many different polypeptides can be created.

• 4²⁰ = 1,099,511,600,000

• 20⁴ = 160,000

Outline the central dogma of molecular biology.

• DNA ---> RNA ---> Protein

• RNA ---> DNA ---> Protein

• Protein ---> DNA ---> RNA

• Protein ---> RNA ---> DNA

The longest known polypeptide is ______ and contains ______ amino acids.

• titin; 30,000

• aspartame; 3,000

• insulin; 300,000

• catalase; 3,000,000

Select the properties that R groups of amino acids can possess that they affect how the protein folds into its three dimensional shape (multiple answers possible).

• Some are polar (hydrophilic).

• Some are non-polar (hydrophobic).

• Some are positively or negatively charged.

• Some contain sulfur.