Mod 6 Ch. 24

Question 1

Which of the following would NOT be consistent with the idea that a disorder has a genetic component?

Answer 1

The disorder can spread to individuals sharing similar environments

Question 2

Assuming complete penetrance, which type of inheritance pattern is consistent with the pedigree shown here?

Answer 2

Autosomal recessive

Question 3

Which of the following is NOT a common explanation for a dominant disorder?

Answer 3

A change in chromosome number

Question 4

Locus heterogeneity refers to a genetic disorder that..

Answer 4

Is caused by mutations in two or more different genes

Question 5

What is a haplotype?

Answer 5

The linkage of alleles or molecular markers along a chromosome

Question 6

Haplotype association studies are aimed at the identification of a particular ___ based on ___.

Answer 6

Gene, its linkage to other genes or molecular markers

Question 7

Which of the following is NOT a method used in genetic testing?

Answer 7

Chromosome walking

Question 8

Which of the following prenatal genetic testing methods is done in conjugation with in vitro fertilization?

Answer 8

Preimplantation genetic diagnosis

Question 9

A prion is a disease-causing agent composed of..

Answer 9

Protein alone

Question 10

An oncogene is produced from a ___ that has acquired a ___.

Answer 10

Proto-oncogene, gain-of-function mutation

Question 11

Which of the following is a type of genetic change that could produce an oncogene?

Answer 11

All of the above

Missense mutation
Gene amplification
Chromosomal translocation

Question 12

Tumor-suppressor genes promote cancer when..

Answer 12

Their function is inactivated

Question 13

Normal (nonmutant) tumor-suppressor genes often function..

Answer 13

• as negative regulators of cell division

- in the maintenance of genome integrity

Question 14

Most forms of cancer involve..

Answer 14

The activation of multiple oncogenes and the inactivation of multiple tumor-suppressor genes

Question 15

Personalized medicine may be used..

Answer 15

• to characterize types of tumors
• to predict the outcome of certain types of cancers
• to determine the proper dosage of drugs

Question 16

A family pedigree of Tay-Sachs disease, indicating recessive inheritance.

What feature(s) of this pedigree indicate recessive inheritance?

Answer 16

The key feature is that affected offspring have both parents who are unaffected by the disease. The parents are heterozygous carriers.

Question 17

A family pedigree of Huntington disease, indicating dominant inheritance.

What feature(s) of this pedigree indicate dominant inheritance?

Answer 17

That affected offspring have an affected parent

Question 18

A family tree of hemophilia A in the royal families of Europe, indicating an X-linked recessive inheritance.

What feature(s) of this pedigree indicate X-linked recessive inheritance?

Answer 18

That all the affected individuals are males. Furthermore, these males all have mothers who were descendants of Queen Victoria

Question 19

What is a haplotype?

Answer 19

Refers to the linkage of alleles or molecular markers along a chromosome

Question 20

The transmission pattern of a molecular marker for Huntington disease.

Explain the connection between the founder and the G8-C marker.

Answer 20

In this example, the original mutation that caused the Huntington allele occurred in a germ-line cell or gamete of a founder such that the Huntington allele was linked to the G8-C marker.

Question 21

A proposed molecular mechanism of prion diseases.

Where does the PrP^Sc protein come from?

Answer 21

May come from eating infected meat or some people have a genetic predisposition that occasionally caused the PrP^C protein to convert to the PrP^Sc protein.

Question 22

Functional cycle of the Ras protein.

How would a mutation that prevents the Ras protein from hydrolyzing GTP affect the EFG pathway described?

Answer 22

Such a mutation would keep the Ras protein in an active state and thereby promote cancerous growth. The EGF pathway would be turned on.

Question 23

The reciprocal translocation commonly found in people with chronic myelogenous leukemia.

Why does this translocation cause leukemia rather than cancer in a different tissue type, such as the lung?

Answer 23

The bcr gene is expressed in white blood cells. This translocation causes abl gene to be under the control of the bcr promoter. The abnormal expression of abl in white blood cells causes leukemia.

Question 24

Interactions between the Rb and E2F proteins.

If a cell cannot make any Rb protein, how will this affect the function of E2F?

Answer 24

E2F will be active all of the time, and this will lead to cancer.

Question 25

Cell-cycle control.

What is a checkpoint?

Answer 25

A point in the cell cycle in which proteins detect is the cell is in the proper condition to divide. If an abnormality such as DNA damage is detected, the checkpoint proteins will halt the cell cycle.

Question 26

Inheritance pattern of familial breast cancer.

Explain why familial breast cancer shows a dominant pattern of inheritance in a pedigree even though it is recessive at the cellular level.

Answer 26

An individual with a predisposition for familial breast cancer inherits only one copy of the mutant allele. Therefore, it shows a dominant pattern of inheritance. However, to actually get breast cancer, the other allele must become mutant in somatic cells.