Genetics Exam 2 Textbook Questions

How many alleles for the single gene trait of blood type (A, B, O) does a person with the normal number of chromosomes inherit from his or her biological parents?

2

How are gene penetrance and gene expressivity different?

With penetrance, the gene is either expressed completely or is not expressed at all; with expressivity, the gene is always expressed, but the degree of expression can range from minor to extreme.

Why are X-linked-recessive disorders expressed in males more frequently than in females?

Hemizygous X alleles in males have homozygous expression.

Which types of traits or health problems cannot be predicted or explained using Mendelian rules?

Polygenic traits/health problems

Which disorder demonstrates a strong gene–environment interaction?

Diabetes mellitus type 2

Which statement or condition best reflects pleiotropy?

A mutation in a single gene results in the expression of problems in a variety of organs.

Which common health problem has the lowest heritability estimate?

Congenital heart disease

Under which condition for a complex disorder is the problem more likely to recur in a family?

The affected child is male, and the disorder usually occurs among females.

What did we learn from the Dutch hunger winter?

Nutrition events have impacts on future generations

What happens in the process of methylation?

Gene expression is turned off

When the area around oncogenes is hypomethylated, what happens to gene expression?

Gene expression increases

How does bisphenol A (BPA) cause epigenetic changes?

BPA can alter the production of microRNAs

What did we learn from studies with agouti mice?

When mother mice were fed higher levels of supplements, their offspring were browner, leaner, and healthier.

How does the microbiome interact with the environment?

Major dietary changes can alter the microbiome

Why do balanced translocation carriers have normal development and function?

They have the correct amount of chromosomal material, and only its location is abnormal.

Which chromosomes are most likely to be involved in a Robertsonian translocation?

Chromosome 13 and Chromosome 14

What is the difference between triploidy and trisomy?

Triploidy involves an extra copy of every chromosome, and trisomy involves an extra copy of only one chromosome

Which clinical feature is a common finding for infants with trisomy 21, trisomy 18, and trisomy 13?

Single palmar crease

What is the risk for a woman with Down syndrome to produce a child with Down syndrome when impregnated by a man who has normal chromosome numbers?

Less than 50%

A friend of yours is concerned that he may be a “carrier” for Down syndrome because both he and his siter have a “simian” crease on one hand. What is your best action or response?

Explain that chromosomally normal people often have one or more featues associated with Down syndrome.

Which chromosomal trisomy is most often conceived?

Trisomy X

Which genetic disorder is associated with older parental age at conception?

Klinefelter syndrome

What mechanism is the most probable reason that females with a 47, XXX karyotype usually have a normal phenotype?

Consistent inactivation of two of the three X chromosomes

Which health problems are common to both Turner and Klinefelter syndromes? Select all that apply

germ cell tumors, osteoporosis, infertility

What does injection of testosterone fail to induce male secondary sex characteristics in females who are 46, XY with complete androgen insensitivity?

Their target tissues for testosterone lack testosterone receptors.

Which situation or condition best exemplifies anticipation?

A son with a genetic problem expresses symptoms 20 years earlier than his mother did

A 39-year-old man with mitochondrial disease is in profound heart failure. What is the source of the heart failure?

Failure of the heart muscle cells to contract effectively because of decreased cellular energy production

A 21-year-old soldier disappeared in Vietnam. Forty years later, bones are discovered that may include his remains. Which available living relative’s mitochondrial DNA would provide the most accurate comparison sample to determine whether the bones belong to the soldier?

Sisters son

Which molecular mechanism is responsible for the phenotype of fragile X syndrome?

Presence of excessive trinucleotide repeat sequences in the noncoding regions of the FMRI gene.

What is the inheritance pattern for this pedigree?

Autosomal dominant

What is the inheritance pattern of this pedigree?

Autosomal recessive

What is the inheritance pattern for this pedigree?

Autosomal recessive

What is the pattern of inheritance for this pedigree?

X-linked recessive

What is the pattern of inheritance for this pedigree?

Autosomal dominant

An asymptomatic 28-year-old woman with a three-generation family history of breast cancer diagnosed at early ages comes to the clinic to see if she has a mutation(s) that could increase her susceptibility to this malignancy. Her diagnosed relatives are no longer living and did not have germline testing before their deaths. What type of testing could be appropriate?

Presdispositional testing

A healthy couple with an Ashkenazi Jewish background comes to the genetics clinic and would like to know if they could pass on a recessive condition to their baby. Which type of genetic testing would be appropriate for this couple?

Carrier genetic screening

Presympotomatic genetic testing would be appropriate for which of the following disorders?

Huntington Disease

A woman with a family history of a breast cancer gene mutation is tested for the known variant. How would you explain her results?

If she has a positive result, she has a much greater risk of developing breast cancer than does the general population

Which type of genetic testing has a high reliability and a low risk of complications?

cfDNA testing

Which of the following groups has the authority to regulate all laboratory testing?

Food and Drug Administration

Which characteristics of a tumor are associated with accelerated cell growth?

Driver mutations

Which traits maintain the limited mortality of a normal cell?

Programmed number of cell divisions

A tumor of unknown origin resembles which tissue type?

Unidentifiable parental tissue type

By which process does epigenetics assist in cancer development?

Hypomethylation of the tumor DNA

A patient is diagnosed as being at high risk of developing breast cancer. Which statement indicates the step of promotion in carcinogenesis?

“I have taken estrogen medication for 30 years”

An 85-year-old patient tells you she does not perform breast self-exams because there is no history of breast cancer in her family. What is your best response?

“Breast cancer can be found more frequently in families; however, the risk for general, sporadic breast cancer increases with age.”

A 36-year-old patient who has suspicious mammogram tells you that her mother died of bone cancer when she was 40 years old. Your follow-up question, “Did your mother ever have any other type of cancer?'“reveals a history of breast cancer. What is your next response to the patient”

“Are you aware that breast cancer frequently will metastasize to the bone, causing complications?”