Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, c^k and c^a. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.

Based on the concepts of dominance, determine whether ck and ca were dominant or recessive alleles by crossing the true-breeding sepia hamsters to true-breeding black hamsters. From the resulting F1 progeny phenotype, what would be the ratio of F2 phenotype

TLS Online TPP Program

#Question id: 33478

#Unit 2. Cellular Organization

Find true and false statements

A. Comparisons of related genes in different species show that the sequences of the corresponding exons are usually conserved

B. when two genes are related, the relationship between their exons is closer than the relationship between their introns.

C. The sequences of the introns are much less similar.

D. Introns evolve much more rapidly than exons because of the lack of selective pressure to produce a polypeptide with a useful sequence.

TLS Online TPP Program

#Question id: 33479

#Unit 2. Cellular Organization

TLS Online TPP Program

#Question id: 33480

#Unit 2. Cellular Organization

Finding: The overall degree of divergence between two homologous exons in related genes corresponds to the differences between the polypeptides.

Reason: Overall degree of divergence between two homologous exons is mostly a result of base substitutions.

TLS Online TPP Program

#Question id: 33481

#Unit 2. Cellular Organization

A. In homologous introns, the pattern of divergence involves both changes in length.

B. Divergence in introns is due to deletions and insertions and base substitutions. 

C. Introns are slowly evolve while exons much more rapidly 

D. When a gene is compared among different species, there are instances where its exons are homologous but its introns have diverged so much that very little homology is retained.

TLS Online TPP Program

#Question id: 33482

#Unit 2. Cellular Organization

Find true and false statements

A. In general, mutations occur at the same rate in both exons and introns, 

B. Exon mutations are eliminated more effectively by selection.

C. Introns may more freely accumulate point substitutions and other changes.

TLS Online TPP Program

#Question id: 33483

#Unit 2. Cellular Organization

Which of the following is correct

A. A set of homologous genes should share common features that preceded their evolutionary separation.

B. All globin genes have a common form of organization with four exons and one introns.

C. A gene family is defined as a group of genes that encode related or identical products as a result of gene-duplication events.