Question 1. List the following items in order
of size from the smallest to largest:
• A. Nucleosome smallest__C_____
• B. Mitochondrion __A_____
• C. Diameter of a DNA molecule Largest__B_____ Question 3. Fill in the blanks:
• Disulfide bonds can form between two
cysteine side chains in proteins.
• The 5’end of RNA is capped by the
addition of 7-methylguanosine .
• Nucleotides are joined together by
phosphodiester linkage between 5’and 3’
carbon atoms to form nucleic acids. Question 4. Short answers.
A. Cholesterol comprises up to 50% of membrane lipids in
many animal cells. Explain in no more than two
sentences why it is not possible to form lipid bilayers with
• Membranes are stabilized by phospholipids which are
strongly amphipathic, that is with very strong hydrophilic
(charged, both (+) and (-) as well as with polar groups)
and very strong hydrophobic hydrocarbon chains of
12-22 carbons in length. Cholesterol is not sufficiently
amphipathic to form a stable bimolecular leaflet in which
the only hydrophilic group is the hydroxyl, with is only
weakly polar. The rest of the molecule is completely
hydrophobic. Question 4.