I. In humans, chromosome 16 sometimes has a heavilystained area in the long arm near the centromere. Thisfeature can be seen through the microscope but has noeffect on the phenotype of the person carrying it.When such a “blob” exists on a particular copy ofchromosome 16, it is a constant feature of that chromosome and is inherited.A couple conceived a child, but the fetus hadmultiple abnormalities and was miscarried. When thechromosomes of the fetus were studied, it was discovered that it had three copies of chromosome 16 (it wastrisomic for chromosome 16), and that two of thethree chromosome 16s had large blobs. Bothchromosome 16 homologs in the mother lacked blobs,but the father was heterozygous for blobs. Which parent experienced nondisjunction, and in which meioticdivision did it occur?
Genetic Variation
Genetic variation refers to the variation in the genome sequences between individual organisms of a species. Individual differences or population differences can both be referred to as genetic variations. It is primarily caused by mutation, but other factors such as genetic drift and sexual reproduction also play a major role.
Quantitative Genetics
Quantitative genetics is the part of genetics that deals with the continuous trait, where the expression of various genes influences the phenotypes. Thus genes are expressed together to produce a trait with continuous variability. This is unlike the classical traits or qualitative traits, where each trait is controlled by the expression of a single or very few genes to produce a discontinuous variation.
I. In humans, chromosome 16 sometimes has a heavily
stained area in the long arm near the centromere. This
feature can be seen through the microscope but has no
effect on the
When such a “blob” exists on a particular copy of
chromosome 16, it is a constant feature of that chromosome and is inherited.
A couple conceived a child, but the fetus had
multiple abnormalities and was miscarried. When the
chromosomes of the fetus were studied, it was discovered that it had three copies of chromosome 16 (it was
trisomic for chromosome 16), and that two of the
three chromosome 16s had large blobs. Bothchromosome 16 homologs in the mother lacked blobs,
but the father was heterozygous for blobs. Which parent experienced nondisjunction, and in which meiotic
division did it occur?
Step by step
Solved in 2 steps
