BIOL 200 UBC Midterm Questions And Answers With
Latest Set
What bonds form in a primary protein structure? ANS covalent bonds between the backbone,
peptide bonds
What bonds form in a secondary protein structure? ANS non covalent bonds between backbone
What bonds form in a tertiary protein structure? ANS covalent bonds between R groups (i.e.
disulfide), non-covalent bonds between backbone, R groups
What bonds form in a quaternary protein structure? ANS -covalent bonds between R groups (i.e.
disulfide), non-covalent bonds between backbone, R groups
-between 2+ polypeptides
How is a peptide bond formed? ANS condensation reaction between alpha amino group of one
amino acid and carboxyl group of another
Why are some folding patterns not obtainable by primary structures? ANS resonance between C-
O and C-N constrains flexibility, no free rotation around C-N axis
What bonds stabilize primary structures? ANS peptide bonds
What bonds stabilize secondary structures? ANS H-bonds between N-H, C=O groups
What types of structures result from secondary protein folding? ANS alpha helix, beta sheet
Describe the bonds of an alpha helix. ANS carbonyl forms H-bond with H from N-H of a
residue, 4 residues further on sequence (in same chain), side chains point outward
, Describe the bonds of a beta sheet. ANS polypeptide folds back on itself, H-bonds form between
N-H and C=O on neighbouring polypeptide strands, side chains project upwards & downwards
What factors determine which structure forms in secondary folding? ANS interactions between
side chains of amino acid residues in polypeptide such as: steric hinderance, charge repulsion, proline
presence, presence of other chem groups
What bonds stabilize tertiary structures? ANS ionic bonds between side chains, H-bonds, LDF
(weaker so need more to stabilize), covalent disulfide bond between cysteine
How does hydrophobic interactions take part in tertiary formation? ANS most stable when
hydrophobic residues face inwards, surrounded by other parts of the protein
What bonds stabilize quaternary structures? ANS ionic bonds between side chains, H-bonds,
LDF, disulfide bonds
Describe the structure of quaternary folding. ANS multiple polypeptide chains, ea. a subunit,
form a dimer, tetramer, etc., can be all same polypeptide or different
Why are disulfide bonds not found in the cytosol? ANS not an oxidizing environment like lumen
of ER
What amino acids are acidic? ANS aspartic acid (Asp), glutamic acid (Glu)
What amino acids are basic? ANS arginine (Arg), lysine (Lys), histidine (His)
Do acidic amino acids lose or gain protons? Where? ANS lose protons from COOH
Do basic amino acids lose or gain protons? Where? ANS gain protons on NH
What are the functions of membranes? ANS -transport of molecules, cell products
Latest Set
What bonds form in a primary protein structure? ANS covalent bonds between the backbone,
peptide bonds
What bonds form in a secondary protein structure? ANS non covalent bonds between backbone
What bonds form in a tertiary protein structure? ANS covalent bonds between R groups (i.e.
disulfide), non-covalent bonds between backbone, R groups
What bonds form in a quaternary protein structure? ANS -covalent bonds between R groups (i.e.
disulfide), non-covalent bonds between backbone, R groups
-between 2+ polypeptides
How is a peptide bond formed? ANS condensation reaction between alpha amino group of one
amino acid and carboxyl group of another
Why are some folding patterns not obtainable by primary structures? ANS resonance between C-
O and C-N constrains flexibility, no free rotation around C-N axis
What bonds stabilize primary structures? ANS peptide bonds
What bonds stabilize secondary structures? ANS H-bonds between N-H, C=O groups
What types of structures result from secondary protein folding? ANS alpha helix, beta sheet
Describe the bonds of an alpha helix. ANS carbonyl forms H-bond with H from N-H of a
residue, 4 residues further on sequence (in same chain), side chains point outward
, Describe the bonds of a beta sheet. ANS polypeptide folds back on itself, H-bonds form between
N-H and C=O on neighbouring polypeptide strands, side chains project upwards & downwards
What factors determine which structure forms in secondary folding? ANS interactions between
side chains of amino acid residues in polypeptide such as: steric hinderance, charge repulsion, proline
presence, presence of other chem groups
What bonds stabilize tertiary structures? ANS ionic bonds between side chains, H-bonds, LDF
(weaker so need more to stabilize), covalent disulfide bond between cysteine
How does hydrophobic interactions take part in tertiary formation? ANS most stable when
hydrophobic residues face inwards, surrounded by other parts of the protein
What bonds stabilize quaternary structures? ANS ionic bonds between side chains, H-bonds,
LDF, disulfide bonds
Describe the structure of quaternary folding. ANS multiple polypeptide chains, ea. a subunit,
form a dimer, tetramer, etc., can be all same polypeptide or different
Why are disulfide bonds not found in the cytosol? ANS not an oxidizing environment like lumen
of ER
What amino acids are acidic? ANS aspartic acid (Asp), glutamic acid (Glu)
What amino acids are basic? ANS arginine (Arg), lysine (Lys), histidine (His)
Do acidic amino acids lose or gain protons? Where? ANS lose protons from COOH
Do basic amino acids lose or gain protons? Where? ANS gain protons on NH
What are the functions of membranes? ANS -transport of molecules, cell products
