Ch. 16 Bio

In Mendelian inheritance patterns, which of the following statements is accurate about recessive alleles?

A recessive allele will have no noticeable effects on an organism's phenotype if a dominant allele is present. A recessive allele will have an effect on an organism's phenotype if the individual is homozygous for the recessive allele. Recessive alleles can be either on the maternal chromosome or the paternal chromosome.

In humans, the allele for freckles is dominant (F) and the allele for no freckles is recessive (f). An individual who is heterozygous for freckles would have which of the following genotypes?

Ff

In humans, the allele for freckles is dominant (F) and the allele for no freckles is recessive (f). An individual who is heterozygous for freckles would have which of the following phenotypes?

Freckles

The fact that maternal and paternal chromosome pairs align and orient randomly during metaphase of meiosis supports Mendel's

Law of Independent Assortment

Muscular dystrophy (MD) is a group of disorders that involve muscle weakness and loss of muscle tissue. Duchenne muscular dystrophy (DMD) is a rapidly-worsening form of MD. DMD is caused by a defect in the dystrophin gene. The dystrophin protein is a vital part of a protein complex involved in muscle support and structure. DMD is much more common in boys than in girls ( about 1/3500 boys have DMD, girls rarely have DMD). Which statements about DMD are ACCURATE? Check all that apply.

The gene for dystrophin must be on the X chromosome. If a female has a defective dystrophin allele, she will likely have a normal allele to act as a "back up". Males are hemizygous, so they will have DMD even if they have only one defective allele. DMD is inherited as an X-linked recessive trait. A woman who is a carrier for DMD will pass the defective allele to half her sons, and those sons will have DMD.

Consider a diploid cell that contains genes Y, R, and Z on separate chromosomes. What is the likely genotype of a daughter cell if the parent cell with genotype YyRRZz undergoes meiosis?

YRZ

Starting with a 2n=32 cell, at the end of meiosis II there will be

four cells, each n=16

Mendel's Principle of Segregation states that

two alleles of a gene separate during gamete formation such that every gamete receives only one allele