Human genetics, genetic disease, and gene transcription

Biology Study Guide

Question 1

The term phenotype refers to the _________ of an individual.

a.
genetic constitution

b.
appearance of a characteristic or trait

c.
number of chromosomes

d.
number of genes

e.
breeding pattern.

Question 2

With respect to sickle cell
anemia, I write that the genotype of an individual is AS. Which of the
following statements are true?

a. They
will have the sickle cell phenotype.

b. The
genes they carry are A and S.

c. The
alleles they carry are A and S.

d. They
are homozygotes.

e. All
of the above are true.

Question 3

If, in the Hershey Chase
experiment, only 35S entered the bacterial cell in significant amounts, the
conclusions would have:

a.
indicated that protein is the genetic material.

b.
supported the idea that the transforming agent, DNA, was also the genetic
material.

c.
indicated that DNA is the genetic material.

d.
indicated that the transforming material, DNA, was probably not the genetic
material.

e. A
and D are true.

f. b
and c are true.

Question 4

During the replication of DNA:

a.
additional nucleotides are always added to the 3′ end of the growing DNA
strands.

b.
additional nucleotides are always added to the 5′ end of the growing DNA
strands.

c.
additional nucleotides are always added to the 5′ end of one of the growing DNA
strands and to the 3′ end of the other growing strand.

d.
additional nucleotides are always added to both the 3′ and the 5′ ends of both
the growing DNA strands.

e. it
is not known.

Question 5

Which statement is most accurate?

a. DNA
is the genetic material.

b. RNA
is the genetic material.

c. most
always, DNA is the genetic material; rarely, RNA serves this function.

d. most
always, RNA is the genetic material; rarely, DNA serves this function.

e.
protein is the genetic material.

Question 6

Mutations at more than one gene
can cause the same phenotype. For
example several enzymes are used to make methionine. Defects in any of them produce an organism
that cannot synthesize its own methionine.
Oculocutanious albinism can also be caused by defects in several
different genes. Of the following
statements which are true?

a. An
protein may contain polypeptides that
are coded for by different genes.

b.
Enzymes are proteins (usually).

c.
Several different enzymes may be used in a pathway to synthesize a molecule.

d. Gene
involved in specifying the structure of a cell component like melanosomes may
mutate and lead to changes in phenotype.

e. All
of the above are true.

f. Some of the above are true.

Question 7

In a double-stranded DNA
molecule, the percentage of thymine is 28%. What percentage of cytosine is
present?

a. 14%

b. 28%

c. 44%

d. 22%

e. 56%

Question 8

Many types of research about
genes’ roles in cancer employ mice. Why use mice when we wish to cure cancer in
humans?

a. We
cannot study anything about human diseases in humans themselves.

cancers
in mice are identical to those found in humans.

c. Mice
and humans evolved from a common ancestor. We think that processes in mice may
be similar to processes in humans because of this.

d. We
use mice because they are inexpensive to maintain, but their cancers seem
unlike human cancers.

We
think that processes we study in mice may be similar to processes in humans
because mice reproduce quickly.

Question 9

There is one specific DNA change
associated with the allele which causes sickle cell anemia but there are
several alleles which cause cystic fibrosis, each with specific DNA changes.
What may explain this difference?

a. The
sickle cell anemia allele makes a product which functions normally under some
conditions and abnormally under others. This is unusual and only one allele has
been found to produce such an effect for the ? globin gene.

b.
Cystic fibrosis can be caused by lack of the normal protein or a decrease in
the protein function produced by this gene and a number of mutations at
different sites can produce abnormal protein products.

c.
Cystic fibrosis is one phenotype that can be caused by a number of different
genes. Any gene that causes cystic fibrosis has only one abnormal allele.

d. A
and b are true.

e. A
and c are true.

Question 10

If you were going to look for a
gene that was often transcribed, where would you look and why?

Heterochromatin
because this type of chromatin is available to be transcribed.

Euchromatin
because this type of chromatin has fewer tandemly repeated sequences in it.

Heterochromatin
because this type of chromatin has more tandemly repeated sequences in it.

d.
Euchromatin because this type of DNA is available to be transcribed.

None of
the above.