A second hit might occur because of loss of heterozygosity. Explain loss of heterozygosity using your own words. Describe a mechanism by which loss of heterozygosity might arise

A defective gene on chromosome 15 causes Tay-Sachs disease. It is a central nervous system neurodegenerative disease that most often affects infants, though older children and adults can have late-onset forms of the disease. The defective gene prevents the body from making a protein called hexosaminidase A. Without, hexosaminidase A, chemicals called gangliosides build up in the nerve cells of the brain, destroying brain cells. Pedigree information regarding the incidence of Tay-Sachs within a family is depicted above. The row below that indicates the genotypes of individuals II-1, II-2, and III-1 is Select one: a. II-1 II-2 III-1 Aa Aa aa b. II-1 II-2 III-1 XAY XAXa XAXa c. II-1 II-2 III-1 XAY XAXA XaXa d. II-1 II-2 III-1 AA aa Aa

A diploid species with 44 chromosomes (i.e., 22 per set) is crossedto another diploid species with 38 chromosomes (i.e., 19 per set).Define key terms. Make a calculation. Predict the outcome.

Define reciprocal translocations

A cell has two pairs of submetacentric chromosomes, which we will call chromosomes Ia, Ib, IIa, and IIb (chromosomes Ia and Ib are homologs, and chromosomes IIa and IIb are homologs). Allele M is located on the long arm of chromosome Ia, and allele m is located at the same position on chromosome Ib. Allele P is located on the short arm of chromosome Ia, and allele p is located at the same position on chromosome Ib. Allele R is located on chromosome IIa and allele r is located at the same position on chromosome IIb.a. Draw these chromosomes, identifying genes M, m, P, p, R, and r, as they might appear in metaphase I of meiosis. Assume that there is no crossing over.b. Taking into consideration the random separation of chromosomes in anaphase I, draw the chromosomes (with genes identified) present in all possible types of gametes that might result from this cell’s undergoing meiosis. Assume that there is no crossing over.

Two different genes are located on the same chromosome in rabbits. A particular female rabbit is heterozygous for alleles of both genes, with alleles arranged as shown in the diagram to the right. Scientists know that the two genes are on the same chromosome, but do not know their exact relative positions, as indicated by the dashed line. Suppose this female mates with a male rabbit in which the same r. chromosome pair looks like this: Which of the following statements best describes the likelihood that this pair of rabbits would have offspring with a chromosome pair that looks like this: * O More likely if the two genes are not very close together on the chromosome E-i-e R- O Not likely, because the R and e alleles are not on the same chromosome in either parent O More likely if the two genes are very close together on the chromosome O Very likely, because the random assortment of chromosomes during cell division to make sperm or eggs allows for the mixing of all alleles

Cystic fibrosis (CF) is an autosomal recessive trait. A three-generation pedigree is shown below for a family that carries the mutant allele for cystic fibrosis. Note that carriers are not colored in to allow you to figure out their genotypes.      Normal allele =  F      CF mutant allele =  f        What is the genotype of individual #13? A) ff B) FF C) Ff  D) it is impossible to tell

The following diagram represents two nonhomologous chromosomes: A B • C D E F G R S • T U V W X What type of chromosome mutation would produce of the following groups of chromosomes? Q. A B • C D R S • T U V W X E F G

Give biological term for a pair of corresponding chromosomes of the same size and shape , one from each parent.

When stained with Giemsa (G-Banding staining), the centromere will be stained:   Question 28 options:   more robustly (dark band)   less robustly (light band)