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^a and c^k. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.

would mate the true-breeding  c^a c^a  hamsters to the true-breeding c^k c^k  hamsters to produce heterozygous  c^a and c^k  F1 progeny,  the F1 progeny cack  hamsters self fertilized, From the fraction of F2 progeny that have the wild type black phenotype, 

Crosses and their interpretation that would have allowed geneticists to come to the conclusion that ca and ck were likely to be alleles of the different gene. 

What will be the ratio of F2 hamster;

#Question id: 3978

#Unit 3. Fundamental Processes

The 5'-terminal cap structure of eukaryotic mRNAs is a(n):

#Question id: 3979

#Unit 3. Fundamental Processes

“Housekeeping genes” in bacteria are commonly expressed constitutively, but not all of these genes are expressed at the same level (the same number of molecules per cell).  The primary mechanism responsible for variations in the level of constitutive enzymes from different genes is that:

#Question id: 3980

#Unit 3. Fundamental Processes

Which of the following statements correctly describes promoters in E. coli?

#Question id: 3981

#Unit 3. Fundamental Processes

The diagram below represents a hypothetical operon in the bacterium E. coli.  The operon consists of two structural genes (A and B), which code for the enzymes A-ase and B-ase, respectively, and also includes P (promoter) and O (operator) regions as shown.

 When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes A-ase and B-ase are both synthesized at a 50-fold higher rate than in the absence of X.  (X has a molecular weight of about 200.)  Which of the following statements is true of the operon decribed above?

#Question id: 3982

#Unit 3. Fundamental Processes

The diagram below represents a hypothetical operon in the bacterium E. coli.  The operon consists of two structural genes (A and B) that code for the enzymes A-ase and B-ase, respectively, and also includes P (promoter) and O (operator) regions as shown.

 When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes A-ase and B-ase are both synthesized at a 50-fold higher rate than in the absence of X (which has a molecular weight of about 200).  Which one of the following statements is true of such an operon?

#Question id: 3983

#Unit 3. Fundamental Processes

Transcription of the lactose operon in E. coli is stimulated by: