Question 1

What percent of mitochondrial DNA is inherited from the mother:

Accepted Answer

Mitochondrial DNA is solely inherited from the mother. Both male and female children receive 100% of their mitochondrial DNA from their mother.

Question 2

In his professional career, Andy wants to study the risk factors associated with genetic disorders and to provide information and support to parents whose risk factors are high. Andy wants to enter the field called:

Accepted Answer

Genetic counseling refers to a widely available resource that can help potential parents evaluate genetic risk factors in childbearing and enable them to make choices that reflect their values and circumstances.

Question 3

According to the text, most individuals harbor about ______ potentially lethal recessive genes:

Accepted Answer

Most individuals carry about 5 to 8 potentially lethal recessive genes, which can lead to genetic disorders if two copies are inherited.

Question 4

The extent to which biologically related people show similar characteristics is measured by a technique called:

Accepted Answer

Concordance is a technique used to measure the extent to which traits or disorders are shared among biologically related individuals, such as siblings or twins. It reflects the degree of similarity between these individuals in terms of their genetic makeup and environmental influences on development. Genetic engineering and recombinant technology are methods used to manipulate or alter genes, while behavioral genetics is a field of study that explores the interplay of genetics and environment in shaping behavior and mental processes.

Question 5

Viruses used in gene therapy that are capable of penetrating cells and inserting modified DNA into them are called:

Accepted Answer

The viruses used in gene therapy that are capable of penetrating cells and inserting modified DNA into them are called retroviruses. Retroviruses are RNA viruses that have the ability to reverse transcribe their RNA genome into a DNA copy that can be integrated into the host cell genome. This allows for long-term expression of the modified DNA. Recombinant viruses and re-engineered viruses are more general terms that could refer to any virus that has been modified for therapeutic purposes. Macroviruses is not a commonly used term in the context of gene therapy.

Question 6

If it were possible to know exactly what genetic information was contained in an individual's genes, would the field of behavioral genetics have any usefulness?

Accepted Answer

Even if we had complete knowledge of an individual's genome, this would provide only a partial explanation for how that person's traits would be expressed within an interactive environmental context. Understanding how genetic characteristics operate within particular environmental settings is the focus of behavior genetics.

Question 7

If a child has mutated genes on chromosome 15 contributed by the mother, he or she will be at risk for developing _____; if the mutated genes are from the father, he or she will be at risk for developing _____.

Accepted Answer

Prader-Willi syndrome is caused by the loss of function of genes on chromosome 15 that are inherited from the father. Angelman syndrome is caused by the loss of function of genes on chromosome 15 that are inherited from the mother.

Question 8

At birth, Debbie was given a mandatory screening test and tested positive for a disorder that required her to be placed immediately on a restricted diet to control her symptoms. Which of the following is mostly likely the condition for which she is being treated?

Accepted Answer

Phenylketonuria (PKU) is a genetic disorder that leads to the inability to process phenylalanine, an amino acid found in protein. This leads to a build-up of phenylalanine in the body, which can lead to brain damage and intellectual disability if not treated early on with a restricted diet. The other options listed do not typically require a restricted diet at birth.

Question 9

Which of the following disorders occurs only when the gene involved is inherited from the mother and not the father?

Accepted Answer

The answer of Which of the following disorders occurs only...

Question 10

Which of the following genetic disorders is the result from a problem associated with the autosomes?

Accepted Answer

Fragile X syndrome, Turner's syndrome, and Klinefelter's syndrome are all sex-linked disorders. Down syndrome is not a sex-linked disorder, rather it involves an extra chromosome being attached to the 21st pair.

Question 11

Suppose researchers identify a genetic disorder that has negative consequences if the gene is inherited from the mother, but no consequences at all if it is inherited from the father. According to the text, this situation would be:

Accepted Answer

Gene imprinting refers to a phenomenon in which gene expression and phenotype depend on which parent the genes come from.

Question 12

Which of the following types of information would be of LEAST interest to a genetic counselor?

Accepted Answer

Genetic counseling often includes the analysis of parental medical records and family histories to construct a genetic "pedigree," which identifies previous instances where congenital anomalies have occurred. Other techniques, such as parental blood analysis or prenatal screening, can detect many chromosomal or genetic anomalies. Parents' income does not provide information in helping the counselor construct a person's genetic "pedigree."

Question 13

Workers in Dr. Garcia's lab first obtain tumor cells from patients with cancer. They then remove the DNA from the tumor cell nuclei and use enzymes to segment the DNA strands into sections. Finally, they insert the DNA sections in which they are interested into "host" bacteria cells, where the DNA can be reproduced for later use. Dr. Garcia's lab is engaged in work involving:

Accepted Answer

As defined in the textbook, recombinant DNA technology refers to an assortment of highly sophisticated procedures in which DNA is extracted from cell nuclei and cut into segments; the resulting fragments are then joined to self-replicating elements, in essence forming functional gene clones. These are then placed in host bacterial cells to be maintained and cultured.

Question 14

Although most of an individual's DNA is contained in the cell nucleus, some is also contained in the:

Accepted Answer

Some DNA is also contained in the mitochondria, which have their own small circular DNA molecules.

Question 15

George's younger brother is diagnosed at birth with "trisomy-21." Another term for this condition is:

Accepted Answer

As noted in the textbook, The most frequent type of Down syndrome is trisomy-21, in which an extra chromosome is attached to the 21st pair.

Question 16

The field of behavior genetics relies most heavily on data gathered from:

Accepted Answer

Behavior genetics primarily uses data from psychological tests and interviews to study the influence of genetics and environment on behavior.

Question 17

Dr. Smith studies a group of 1,000 people who have schizophrenia and who also have identical twins. He finds that 47% of the identical twins also develop this disease. The type of statistical information Dr. Smith's study reveals is called:

Accepted Answer

The primary tool of behavior genetics is the statistical technique of correlation, which measures concordance: the extent to which biologically related people show similar characteristics.

Question 18

Down syndrome has been shown to be related to which of the following?

Accepted Answer

As noted in the textbook, Down syndrome occurs about once in every 1,000 live births for mothers under age 35, and the incidence steadily increases as the age of the mother increases.

Question 19

Which of the following is the best summary of the current state of gene therapies, such as the use of retroviruses?

Accepted Answer

As noted in the textbook, a gene therapy approach that involves reinserting genetically altered cells into the person from whom they were harvested has been tried with various genetic disorders but with limited success thus far. Additionally, the retrovirus approach also has experienced only limited success; however, it holds great promise for the future if certain technical obstacles can be overcome.

Question 20

Rene has Down syndrome, which means that she has an extra chromosome on which chromosome pair?

Accepted Answer

As noted in the textbook, the most frequent type of Down syndrome is trisomy-21, in which an extra chromosome is attached to the 21st pair.

Quiz 2: Heredity and Environment