Genetics 24

Place the steps by a cloned gene is transferred into human cells using a retroviral technique in order, with the first step at the top

1. A gene of interest is placed into a viral vector.2. The virus is taken up by cells via endocytosis.3. The viral coat disassembles, releasing the viral genome into the cytosol.4. The genome is reverse-transcribed into DNA5. The viral DNA is imported into the nucleus6. The gene of interest is integrated into a chromosome of the target cell by recombination

Which best describes a haplotype?

A haploid genotype showing linkage of alleles or molecular markers along a single chromosome

What is the inheritance pattern for a trait that occurs with the same frequency in both sexes and two affected heterozygous individuals have, on average, 25% unaffected offspring?

Autosomal dominant Reason it is not Recessive: For this pattern, two affected individuals (who would not be heterozygotes), would have 0% unaffected offspring.

What is the inheritance pattern when a trait occurs with the same frequency in both sexes and an affected offspring can have two unaffected parents?

Autosomal recessive

The accompanying pedigree shows the inheritance of Huntington disease with filled symbols and also indicates which combination of four possible forms (A, B C, D) of a molecular marker called G8 that the person has inherited. What is the one possible phenotype and marker combination that is missing among the children of the couple surrounded by the circle?

BB with Huntington disease

Suppose a disease-causing allele shows autosomal recessive inheritance. How could a carrier of this disease-causing allele be identified?

Carriers often show reduced activity for the enzyme encoded by the allele.

Which type of mutation causes a dominant genetic disorder through the production of an altered protein that works against the action of the normal protein?

Dominant-negative

Which observations are consistent with a disease having a genetic basis?

One family in the neighborhood has one parent and several children with severe hearing loss. No one in any of the other nearby families has deafness. Nephroblastoma is a cancer of the kidney that typically develops in children and is only rarely found in adults. Someone with a diagnosis of retinitis pigmentosa has learned that there are family members in the preceding three generations who had the disease.

What tool do scientists use to follow a human pattern of inheritance from generation to generation?

Pedigree analysis

What is the inheritance pattern for a trait that more commonly affects males than females and can often be observed in brothers or fathers of a woman who has affected sons?

X-linked recessive

Consider the accompanying partial pedigree showing inheritance of hemophilia in the family of Queen Victoria and Prince Albert. If Xh is the allele for hemophilia and XH is the allele for normal blood clotting, which genotypes are missing among the children of Alice of Hesse and her husband, in the middle of the figure?

XHXH XHY

A dominant genetic disorder can be caused by ______, a situation where one functional copy of an allele is not sufficient to produce a normal phenotype. Multiple choice question.

haploinsufficiency

Genetic testing is used to determine whether a(n) ______ has a disease-causing gene, while genetic screening is used to determine how frequently the gene is found in a(n) ______.

individual; population

A situation where a disease may be caused by mutations in two or more different genes is called ______.

locus heterogeneity

Simple Mendelian inheritance is a pattern observed when a human disorder is caused by ______.

mutation in a single gene

A disease-causing agent made only of protein is called a ______.

prion

The International HapMap Project is an effort to identify differences in human DNA sequences by identifying ______.

single-nucleotide polymorphisms

Which of the following characteristics of inheritance can be observed in the accompanying pedigree of a family affected by Tay-Sachs disease?

The trait occurs in both males and females. An affected offspring can have two unaffected parents. Affected individuals are offspring of heterozygous parents.

What is the inheritance pattern for a trait that more commonly affects males than females and which will occur in about 50% of the sons born to the unaffected daughter of an affected male?

X-linked recessive