Biology

A diploid cell of baker's yeast has 32 chromosomes. How many chromosomes are in each of its haploid spores?

16

A person with cystic fibrosis has _____ non-functional copies of the CFTR protein.

2

How many chromosomes are in a human sperm?

23

A human female has _____ chromosomes in each skin cell and _____ chromosomes in each egg.

46; 23

In an otherwise normal cell, what happens if one mistake is made during DNA replication?

A cell cycle checkpoint detects the error and pauses the cell cycle so the error can be corrected.

Why is age a risk factor for cancer?

Age extends the amount of exposures to environmental factors, which can lead to the progression of cancer.

What is the role of BRCA1 in normal cells?

BRCA1 acts as a tumor suppressor.

How does a somatic mutation in a gene alter the function of a cell?

Base pair mutations in a gene are passed directly into mRNA via transcription.

A person has cystic fibrosis. What does this mean about their alleles in the cystic fibrosis gene?

Both are non-functional.

A test designed to look for different alleles of a gene (e.g., the BRCA1 gene) is based on differences in:

DNA sequences.

What would be the best way to distinguish between two alleles and two genes?

Examine their DNA; the DNA sequences of two different alleles would be more similar than the sequences of two different genes.

Which of the following statements accurately describes cancer development?

It is a multistep process by which multiple mutations cause a series of events that lead to cancer.

A proto-oncogene is critical for a cell to respond to an external signal to divide. What would happen to a cell that sustains an inactivating mutation in this proto-oncogene?

It would not divide, even in the presence of a signal to divide.

In general, what is the likelihood that women who inherit BRCA gene mutations will develop breast cancer in their lifetime compared to women without BRCA mutations?

Women who inherit BRCA mutations are more likely to develop breast cancer.

Which of the following women would be most likely to benefit from genetic testing for breast cancer?

a 25-year-old woman whose mother, aunt, and grandmother had breast cancer

A nucleotide insertion occurs in the middle of the coding sequence of a gene involved in accurately separating chromosomes during mitosis. What is/are possible outcomes?

a change in the amino acid sequence of the protein a change in the protein's shape a change in the protein's function inaccurate division of the cell, resulting in cancer

What is an "inherited" or "hereditary" cancer?

a mutation that predisposes an individual to cancer passed from parent to child

If cells from a malignant breast tumor in a 27-year-old woman were examined, what would be expected?

a single mutation in a tumor-suppressor gene, such as BRCA1 oncogenes a mutation that permits new blood vessel growth a mutation in the p53 gene

Which of these statements about decreasing a woman's breast cancer risk if she inherits one of the mutant BRCA genes is TRUE?

a. Diet and lifestyle changes will effectively decrease her risk to near zero. b. She can take several medications that make it almost impossible to get breast cancer, even if she inherits the BRCA gene. c. Surgical removal of the breasts will decrease a woman's cancer risk to near zero. d. A woman cannot decrease her cancer risk, so she might as well live life to its fullest. e. None of the above is true.

What would you say to a niece if she asked you how she could reduce her risk of breast cancer? (Assume there is no family history of breast cancer.)

a. Reduce sun exposure. b. Reduce alcohol consumption. c. Avoid tobacco. d. Utilize early screening.

Which of the following does not cause cancer to develop and progress?

a. a proto-oncogene c. a tumor suppressor gene

A mutation can cause a change __________.

a. in the amino acid sequence of a protein b. in the shape of a protein c. in the way the cell cycle is regulated d. that is beneficial to the cell

Why do people with "inherited cancer" often develop cancer at a relatively young age?

aPredisposition increases the chances that other risk factors will lead to the progression of cancer. c. Cancer cannot be truly inherited, but certain alleles weaken the normal control points that prevent cancer, and this causes cancer to appear earlier in life.

We would all have many more mutations in our genes if not for the __________.

activity of proofreading enzymes

At which of the following points does a mutation exert its potentially dysfunctional effects in a cell?

after a protein is produced

A mutated form of a proto-oncogene is called:

an oncogene.

If an individual has a germline mutation, which of the following are possible sources of that mutation?

b. a maternal allele c. a paternal allele

Tumors that will not spread throughout the body are _________________, and those that do spread are termed ______________.

b. benign; malignant

A woman with a BRCA1 mutation __________.

b. is at increased risk of developing breast cancer

Why does wearing sunscreen reduce cancer risk?

c. Sunscreen can reduce the chance of mutations caused by exposure to UV radiation present in sunlight.

DNA mutations can arise from uncorrected errors in DNA replication, inheritance, and __________.

c. environmental insults

Which is the correct order of events in which breast cancer might develop?

d. inheritance of a mutant BRCA gene > replication errors create an oncogene > mutation of p53 > additional mutations permit spreading

An allele that can mask the presence of a recessive allele is a _____ allele.

dominant

The normal form of the BRCA1 protein is protective because BRCA1 protein:

helps cells repair damaged DNA during the cell cycle.

A person has the identical BRCA1 mutation in every somatic cell in their body. What is the most likely source of this mutation?

inheritance from one of their parents (via the sperm or egg)

Most cancerous cells have __________ mutation(s).

many

Which of the following family histories most strongly suggests a risk of inherited breast cancer due to BRCA1 mutations?

many female relatives with both early breast cancer and ovarian cancer

A chemical that causes alterations in DNA is a ______________, and if this chemical causes cancer it is called a _______________.

mutagen; carcinogen

normal function of tumor-suppressor genes, such as BRCA1 or p53?

produce proteins that induce apoptosis produce proteins that repair DNA damage produce proteins that suppress the cell cycle when there is DNA damage

What is the normal function of a proto-oncogene?

to help the cell divide appropriately

A potential cancer-causing gene coding for a protein with cell cycle control responsibilities is a ___________, and a gene coding for a protein that stimulates cell division is a ___________.

tumor suppressor; proto-oncogene

An individual who inherits a mutation in a BRCA1 or BRCA2 gene is at higher risk for developing cancer because these genes are:

tumor-suppressor genes that produce proteins to repair DNA damage.

Which of the following combinations of mutations is the most likely to convert a normal cell to a cancerous cell?

two mutated p53 alleles, two mutated BRCA1 alleles, one activated allele of HER2