MCDB 100 Midterm Questions/Answers
Jan 8, 2008 O’Lague
1. What are two major pieces of molecular evidence that we all evolved from a
Ans: We all use DNA and a universal triplet code.
2. What are the major differences between prokaryotic and eukaryotic cells?
Ans: haploid circular DNA vs. diploid linear DNA, nucleus, organelles, cytoskeleton.
3. In an EM picture of a part of a eukaryotic cell, name the major structures.
Ans: locate nucleus, Golgi, ER, mitochondria, cell membrane, lysosomes,
peroxisomes, smooth ER.
4. What are the advantages, if any, in being multicellular?
Ans: Cells can specialize by food storage and cell movement and cells feed each
other in a complementary fashion.
5. What are three major functions of the cytoskeleton?
Ans: cell movement, cell shape, and transport of molecules and organelles within
6. What is the origin of mitochondria?
Ans: Probably an Archaea bacteria eating a eubacteria.
7. Why are yeast model organisms useful for molecular studies?
Ans: primitive and simplest Eukaryote with a haploid genome.
8. The majority of Chinese hamster ovary (CHO) cells grown in tissue culture in the
presence of methotraxate die, a few survive that grow in its presence. What biological
principle(s) is involved in this behavior?
Ans: natural selection through the appearance of drug resistance maybe due to
spontaneous mutation, but other explanations are possible like overexpression of
pre-existing drug resistance in a minority of CHO cells.
9. What are the three major divisions of life?
Ans: Archaea, Eubacteria, and Eukarytoa.
10. DNA double helix folding is spontaneous, going from a disorderly state (random
unfolded to an ordered state (double helix). But this violates the Second law of
Thermodynamics, or does it? Use
S to explain.
Ans: If folding is spontaneous,
G must be negative, but T
S, the entropic term, is
H, the heat term must be negative and larger. This means heat is given
off to water when H bonds are formed in the DNA, i.e. the kinetic energy of the bases
are given off to water as they form H bonds.