BIS 2A Study Guide - Final Guide: Lac Operon, Operon, G1 Phase
FINAL EXAMINATION
1. Exons are...
a. genes for proteins that will be excreted from a cell.
b. groups of genes in bacteria that are controlled together.
c. extremely important genes.
d. separated by introns in many eukaryotic genes.
e. removed from an mRNA before the mRNA is exported to the cytoplasm.
2. In one strain of E. coli, a mutation in the gene that codes for the repressor of the lac
operon alters the lactose-binding site of the repressor and thus prevents lactose from
binding to the protein. In all other ways, the repressor stays the same. Which of the
following statements represents a reasonable expectation?
a. The strain will never make ß-galactosidase.
b. The strain will always make ß-galactosidase.
c. The strain will make ß-galactosidase only in the presence of lactose.
d. The strain will make ß-galactosidase only in the absence of lactose.
e. The strain will make huge amounts of repressor instead of ß-galactosidase.
3. In bacteria, genes for related functions are often found in “operons.” What is the
significance of this observation?
a. Only genes in operons can ever be used as templates for mRNA synthesis.
b. Genes in operons are constitutively transcribed (transcribed all the time).
c. All operons are controlled by one repressor protein.
d. All genes in all operons are transcribed only in the presence of lactose.
e. Two or more genes in one operon are transcribed at the same time and under the
same conditions.
4. Many proteins in eukaryotes have a “leader sequence,” a short chain of amino acids
that allows them to be inserted into the endoplasmic reticulum. These proteins could
wind up...
a. inside a lysosome.
b. as an intrinsic protein in the plasma membrane.
c. outside the cell.
d. inside the vacuole (assuming a plant or fungal cell).
e. any of the above.
5. In the presence of an inhibitor of microtubule formation, dividing cells will tend to be
found in what phase of the cell cycle?
a. prophase or prometaphase
b. S phase
c. anaphase
d. G1 phase
e. An inhibitor of microtubule formation will not affect the cell cycle of dividing
cells, so cells will be found in all phases.
6. What phase of mitosis best describes the cell diagrammed below?
a. Prophase
b. Prometaphase
c. Metaphase
d. Anaphase
e. Telophase
7. Gametes are best described as...
a. haploid cells that fuse to form a zygote.
b. haploid cells that are always produced by meiosis.
c. diploid cells that undergo a series of mitotic divisions to form an adult
organism.
d. haploid cells that undergo a series of mitotic divisions to form an adult
organism.
e. male and female diploid cells that fuse at fertilization.
8. Meiosis differs from mitosis in that...
a. the cells that are produced by mitosis are always diploid.
b. homologous chromosomes do not separate in meiosis.
c. only cells in mitosis have spindles.
d. meiosis occurs only in diploid cells.
e. chromosome replication is followed by one division in meiosis, two in mitosis.
9. The cell to the right was found in an
organism that is known to have a diploid
number of chromosomes equal to 6 (2n=6).
Which of the following statements best
describes the cell?
a. The cell is the product of an
abnormal meiosis.
b. The cell is in prophase I of
meiosis.
c. The cell is in prophase II of
meiosis.
d. The cell is in telophase II of
meiosis.
e. The cell is in anaphase of mitosis.
10. Meiosis is an important stage in a species’ life cycle because...
a. after going through meiosis, one cell produces a large number of gametes.
b. the products of meiosis have a reduced number of chromosomes per nucleus.
c. the chromosomes in the products of meiosis may have new combinations of alleles.
d. without meiosis, it would be impossible to form a multicellular organism.
e. both b and c are true.
11. The response of normal basal or squamous skin cells that are exposed to intense sunlight
may include...
a. the excision of damaged DNA bases and resynthesis of the DNA chain.
b. a delay in the rate of cell division
c. apoptosis (programmed cell death)
d. all of the above.
e. none of the above.
12. True or false: a mutation, for instance in the gene that codes for hemoglobin, can occur from
a simple error by DNA polymerase in finding a proper complementary base during DNA
replication.
a. true b. false
Document Summary
In all other ways, the repressor stays the same. Only genes in operons can ever be used as templates for mrna synthesis. b. Yet in recent years, e. coli has been recognized as a serious pathogen, responsible for many instances of sickness in people who have eaten contaminated foods. Staphylococcus bacteria have become more resistant to penicillin in recent years. Retroviruses are not difficult to eliminate from the body: in addition to its general characteristics as a retrovirus, hiv is particularly difficult for the immune system to eliminate from the body, because its binding to________means that it infects. Th cells and macrophages: antibodies, cd4 receptors, gp120, mhc i, mhc ii. The diagram at the right represents a bacterial cell as it might have been drawn in lecture. Questions 31-37 refer directly or indirectly to this diagram: the function of the organelle marked. Mutant 1 can grow on compound b, but not a or c.
