Question

1. let's say CFTR (encoding the CFTR Cl- channel) has two alleles: + (which encodes a functional product) and - (which encodes a non-functional product). CFTR is a Cl- transporter expressed in many epithelial cells. LDLR is on chromosome 7. A person with the -/- genotype has Cystic Fibrosis but those with either +/- or +/+ genotypes do not. Which of the following is true?

		a. Cystic Fibrosis is autosomal recessive because a person must have two copies of the "-" allele to express the phenotype
		b. Cystic Fibrosis is autosomal dominant because the "+" allele is the normal version
		c. Cystic Fibrosis is autosomal dominant because the "+" allele is the most common in the population
		d. Cystic Fibrosis is autosomal dominant, because a person must have two copies of the "-" allele to express the phenotype
		e. Cystic Fibrosis is autosomal recessive because it is the "-" allele that causes the disease

2.

let's say SLC2A4 (encoding the insulin-dependent glucose transporter GLUT4) has two alleles: + (which encodes a functional product) and - (which encodes a non-functional product). If GLUT4 expression is necessary to not have diabetes, which of the following can we definitely conclude? (More than one answer may seem correct but only one answer logically follows the information)

		a. a +/- genotype will have a mild form of diabetes
		b. a -/- genotype will have diabetes
		c. a -/- genotype may not have diabetes
		d. a +/- genotype will have a 50% probability of diabetes
		e. a +/+ genotype will not have diabetees

3.

a pretty good definition of a gene is

		a. one of the homologous chromosome inherited from either the egg (mother) or sperm (father)
		b. a discrete segment of DNA that encodes a functional product
		c. one of two or more alternative forms of nucleotide that arise by mutation and are found at the same place on a chromosome.
		d. the mRNA that is translated into a polypeptide
		e. the bluprint for the phenotype

4.

In the chart:

A	B	C	D
+/+	100% functional protein	watery	no disease
+/-	50% functional protein	intermediate	no disease
-/-	0% functional protein	thick	disease

What is in column A?

		a. different genes
		b. different phenotypes
		c. different genotypes
		d. different loci
		e. different proteins

Answer 1

1)

A) Cystic Fibrosis is autosomal recessive because a person must have two copies of the "-" allele to express the phenotype.

As both the Alleles for the CFTR gene must be mutated for Cystic Fibrosis to occur, Cystic Fibrosis is recessive. This disorder is termed Autosomal, as the gene for CFTR is on Chromosome 7,which is an autosome.

2)

C) a -/- genotype may not have diabetes

Since the presence of the GLUT4 Receptor is required for a person not to develop diabetes, a person who has no functional copies of the gene may develop diabetes. However, it is not necessary that such a person will have diabetes, and they may not have diabetes.

3)

B) a discrete segment of DNA that encodes a functional product

Of all the given options this is the closest to the definition of a gene. This is because it covers the basic features of a gene in that it occupies a certain portion of the chromosome or genome, and that a gene encodes a functional product.

4)

C) different genotypes

The +/+, +/-, - /- noted in the first common denote three different genotypes. The fist one is the Homozygous Wildtype, the second one is heterozygous, with one wild type copy of the gene and one mutant copy, and the third is a homozygous mutant genotype, where both copies are mutants.