Biochem practice problems

1.	Which of the following is the most abundant element in the human body?
	A)	nitrogen
	B)	carbon
	C)	oxygen
	D)	phosphorous
	E)	none of the above

C) oxygen

proteins

structure, enzyme

nucleic acids

information

lipids

membrane, energy

polysaccharides

energy storage

Which of the following molecules contains the most oxidized form of carbon?
	A)	acetaldehyde
	B)	ethanol
	C)	acetic acid
	D)	ethylene
	E)	carbon dioxide

E) carbon dioxide

Which of the following correctly identifies the progression from individual molecules to a functioning multi-cellular organism?
	molecules, cell, organelle, organ, organism
	molecules, organelle, organ, cell, organism
	molecules, organelle, cell, organ, organism
	molecules, organ, organelle, cell, organism
	molecules, cell, organ, organelle, organism

Molecule → organelle → cell → organ → organism

Hydrogen bonds are approximately _____% of the bond strength of covalent C-C or C-H bonds.

A. 1

B. 5

C. 20

D. 50

E. 95

B) 5

Hydrogen bonds within liquid water are _________.

A. attractions between the protons of the oxygen nuclei

B. ion-induced dipole interactions

C. dipole-dipole interactions

D. attractions between two oxygen atoms

E. attractions between the H+ and -OH ions of the liquid

C. dipole-dipole interactions

Considering the energetics of transferring nonpolar molecules from water to a nonpolar solvent, the factor TDS is generally _____, causing DG to be _____.

A. positive: negative

B. negative; negative

C. positive; positive

D. negative; positive

E. ngligible; either positive or negative

A. positive: negative

What would be the resulting pH if one ml of 1.0 M NaOH was added to one liter of pure water (assume pH 7.0)?

A. 1

B. 3

C. 7.3

D. 11

E. 13

D. 11

What is the conjugate acid of H₂PO₄^-?

add a proton

H3PO4

At a pH above its pKa, the phenolic group of tyrosine is ___.

A. protonated and neutral

B. protonated and positively charged

C. deprotonated and neutral

D. deprotonated and negatively charged

E. none of these choices

D. deprotonated and negatively charged

Which of the following structures shows the prevalent form of glutamic acid at pH 3?

A.

B.

C.

D.

E none of these

C.

What is the N-terminal residue of the peptide AYSDG?

A. glutamic acid

B. glycine

C. aspartic acid

D. alanine

E. none of these choices

D. alanine

peptide sequence is written N-terminal → C-terminal

The following is an example of ___.

A. parallel alpha helix

B. parallel B-sheet

C. antiparallel alpha helix

D. antiparallel B-sheet

E. none of these choices

D. antiparallel B-sheet

Given pKa values of 2.3 and 9.7, what is the pI of alanine?

A. 12

B. 7.4

C. 6

D. 4.2

E. none of these

C. 6

A technique for determining protein structure that requires crystals of the protein is ___.

A. NMR spectroscopy

B. X-ray crystallography

C. Electron crystallography

D. mass spectroscopy

E. none of these

B. X-ray crystallography