Genetics - Chapter 12

About ______ of all cancers are the result of viral infections making certain viruses a major cause of cancer.

15%

The cell cycle is regulated by _____ main checkpoints.

3

An individual must have a genetic predisposition for cancer in order for it to develop.

False

Chromosomal aberrations, such as aneuploidy and translocations, are rarely observed in cancer cells.

False

Most individuals who are heterozygous for cancer-related alleles will develop cancer at a young age.

False

Mutant BRCA1 and BRCA2 alleles are associated with lower rates of breast and ovarian cancer.

False

The only risk factor for cancer is the transmission of mutant alleles from parent to offspring.

False

The purpose of cell cycle checkpoints is to ensure that cells divide continuously.

False

Traditional cancer therapies target only the cancerous cells; therefore, patients rarely experience side effects of the treatment.

False

Tumor suppressor genes function to promote cell division, while proto-oncogenes function to halt cell division.

False

Unrepaired DNA breaks decrease the rate of cancer causing mutations in genes located at or near break points.

False

Women carrying a mutant BRCA1 or BRCA2 allele do not have an increased risk of developing ovarian cancer.

False

Women who did not inherit a mutation that predisposes them to breast cancer should consider breast removal surgery.

False

​Cancer causing mutations are always the result of chromosomal rearrangements.

False

​There are no direct-to-consumer genetic tests available that screen for breast cancer susceptibility.

False

Whether cells will enter the S phase or will be sent to the G0 (G-zero) non-dividing state is determined by the

G1/S checkpoint

​In rapidly dividing cells, expression of BRCA1 and BRCA2 genes is the highest during the ____.

G1/S transition and into S phase

The ________ cell cycle checkpoint ensures that DNA replication has occurred accurately.

G2/M

This checkpoint makes sure that the DNA has been replicated and that any damage to the DNA has been repaired.

G2/M checkpoint

Gardasil and Cervaix are vaccines that were developed to prevent infection by:

Human papilloma viruses

________ occur(s) when cancer cells migrate away from the primary tumor and form new malignant tumors in other parts of the body.

Metastasis

A tumor arises from the continued cell division of a single cancerous cell.

True

About 40% of human cancers are characterized by mutations in the ras proto-oncogene, which results in uncontrolled cell division.

True

All cancers are caused by mutations.

True

Both BRCA1 and BRCA2 are DNA repair genes.

True

Colon cancer has fewer cellular adhesion and motility mutations but more transport mutations than breast cancer.

True

Epigenetic changes, including abnormal DNA methylation patterns and imprinting, are observed in many cancers.

True

Genetic mutations exist in almost all cancers; however, not all cancers are inherited.

True

Herceptin, a drug for treating breast cancer, competes for the HER2 receptors on the surface of breast cancer cells, blocking them from receiving growth signals and passing them to the cell's nucleus.

True

Men who inherit the mutant BRCA1 or BRCA2 allele are also at risk of developing breast cancer.

True

New research is focusing on developing drugs to stop the growth of cancer cells rather than trying to kill them.

True

Research has shown that viral genes can promote and sustain the growth of cancer in infected cells.

True

Several mutations are required for the development of colon cancer.

True

Since Gleevec binds to the same site as the ATP molecule, ATP cannot provide the signal protein needed to continue cell division; therefore, cancer cells stop dividing and die.

True

Some cancers have high rates of mutation, but most have low rates of mutation.

True

The goal of The Cancer Genome Atlas project is to catalog and understand the DNA mutations found in all cancers.

True

​About one in three people will be diagnosed with cancer at some time in his/her life.

True

​Most of the somatic cells in the body are structurally and functionally specialized and do not divide.

True

​The mutant BRCA1 gene imparts a dominantly inherited predisposition to breast cancer.

True

retinoblastoma

a malignant tumor of eye most prevalent in children

Cancer always begins in:

a single cell

​In most cases, cancer-causing mutations ____.

accumulate over a number of years

There will always be a baseline rate of cancer because ________.

all cancers are ultimately caused by mutations

Exposure to ________ increases the risk for developing lung cancer, which causes 30% of all cancer deaths in the US.

all tobacco products

The field of epigenetics has opened the way for the development of a new class of anticancer drugs ____.

because of the discovery that epigenetic modification of key genes is important in some cancers and the fact that epigenetic changes are reversible

A cell can grow uncontrollably and cause a tumor that is not cancerous, but instead is:

benign

​Cancer-causing mutations of the cell cycle ____.

cause the cell to bypass checkpoints in the cycle

The familial adenomatous polyposis trait for colon cancer is associated with:

chromosomal instability

When six or more mutations in the FAP gene occur in a specific sequence in a certain cell, the result is ________.

colon cancer

The hereditary nonpolyposis trait for colon cancer is associated with:

failures in DNA repair

proto-oncogenes

genes that encode proteins that help regulate the cell cycle by starting and continuing cell division

tumor-suppressor genes

genes that encode proteins that help regulate the cell cycle by turning off or decreasing the rate of cell division

oncogenes

genes that initiate or maintain uncontrolled cell growth

​Stem cells ____.

have the property of self-renewal by division

All cancers have ________.

higher rates of mutation than normal cells

Aberrant DNA methylation can lead to cancer because ________.

hypermethylation can inactivate DNA repair genes

Mutant BRCA1 and BRCA2 alleles ________.

increase the risk of breast and ovarian cancer

During mitosis the attachment of spindle fibers to chromosomes is monitored to enable the anaphase separation of chromosomes. This occurs during

late metaphase

When an individual is heterozygous for a cancer-related allele, s/he may develop cancer after mutation of the other, normal allele, a concept known as ________.

loss of heterozygosity

​The five-year survival rate of ______ cancer is only 13%.

lung

Cells that acquire the ability to divide uncontrollably, and which can break away and move to other locations in the body, are:

malignant

If genetic testing reveals the presence of a breast cancer allele in Anna's mother, but not her maternal aunts, then Anna ________.

may have inherited this allele from her mother

​One of the properties of cancer is its ability to spread, or ________, to other sites in the body.

metastasize

When cells detach from a tumor and move to other locations in the body they are said to have:

metastasized

Abnormal epigenetic patterns of DNA ______ are associated with many types of cancer, and the removal of _______ groups can activate genes involved with cell growth and can increase genomic instability.

methylation; methyl

​When MSH2 and MLH1 are inactivated by mutation, DNA repair is defective and _______ mutation rates increase by at least 100-fold.

microsatellite

By sequencing the genomes of cancer cells, researchers learned that cancer cells contain ________.

more mutations than previously thought

Mutations in DNA repair genes do not in themselves cause cancer, but they do increase the ______ across the genome.

mutation rate

Most cancers are age related since cells only become cancerous after accumulating a specific a number of

mutations

​Drug therapies that target only cancer cells rather than all dividing cells in the body stop the growth of cancer by blocking the action of ________ proteins on the growth and division of malignant cells.

oncogene

​Formation of _______ is an intermediate stage in the development of colon cancer.

polyps

At each checkpoint a combination of external signals and internal ______ determines whether the cell will move on to the next stage of the cell cycle.

regulatory pathways

The ras proto-oncogene family encodes proteins that function in ________, relaying signals from outside the cell across the cell membrane.

signal transduction

​A cellular molecular pathway by which an external signal is converted into a functional response is called ______

signal transduction

For colon/rectal cells to become cancerous, ______ mutations must occur in the cells.

six or more

​According to the American Cancer Society, 30% of all cancer deaths in the U.S. are due to ____.

smoking

Cancer therapies such as Gleevec and Herceptin may be preferable to traditional therapies that use radiation and chemicals because these new therapies ________.

target only cancer cells

The specific translocation forming the Philadelphia chromosome leads to chronic myelogenous leukemia because ________, resulting in continuous cell division.

the BCR gene sequences "switch on" the ABL1 sequences

​A characteristic of all cancers is that ____.

the cells divide continuously

A(n) _______ between chromosome 9 and chromosome 22 in chronic myelogenous leukemia results in a Philadelphia chromosome.

traslocation

The protein product of the p53 gene functions at the G1/S cell cycle checkpoint, pausing the cell cycle if DNA damage occurs; therefore, p53 is a(n) ________.

tumor suppressor gene

Genes that turn off or decrease the rate of cell division are known as _______ genes.

tumor-suppressor

The rise in skin cancer is mainly due to the exposure to ________ in tanning salons.

ultraviolet light

​About ____ of all cancer cases have a hereditary component.

​5% to 10%

​The translocation seen in the Philadelphia chromosome in myelogenous leukemia represents ____.

​a specific chromosomal aberration accompanying a specific cancer

​Hereditary nonpolyposis colon cancers (HNPCC) ____.

​are caused by several mutations in several different genes

​The RB1 tumor-suppressor gene ____.

​controls the G1/S checkpoint

​If a cell begins to divide in an uncontrolled way, it ____.

​may form a benign tumor

​During the M checkpoint, the cell ____.

​monitors attachment of spindle fibers to chromosomes

​During metabolism, cancer-causing ____ are generated.

​reactive oxygen species (ROS)

​A proto-oncogene ____.

​regulates cell division

​Many specialized cells, such as white blood cells, ____.

​remain in G0 until stimulated by external signals to reenter the cell cycle and divide