The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years

Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.

Fitness is a measure of the reproductive success of a particular genotype. The highest fitness is 1.00.

The strong dependence of RR individuals on large quantities of vitamin K probably is responsible for

#Question id: 447

#Unit 1. Molecules and their Interaction Relevant to Biology

In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (DG'°) of 23.8 kJ/mol.  Under what conditions encountered in a normal cell will the free-energy change (DG) be negative, enabling the reaction to proceed spontaneously to the right?

#Question id: 448

#Unit 1. Molecules and their Interaction Relevant to Biology

During glycolysis, glucose 1-phosphate is converted to fructose 6-phosphate in two successive reactions: Glucose 1-phosphate -> glucose 6-phosphate DG'° = –7.1 kJ/mol Glucose 6-phosphate -> fructose 6-phosphate DG'° = +1.7 kJ/mol DG'° for the overall reaction is:

#Question id: 449

#Unit 1. Molecules and their Interaction Relevant to Biology

The standard free-energy changes for the reactions below are given. Phosphocreatine -> creatine + Pi DG'° = –43.0 kJ/mol ATP ->  ADP + Pi DG'° = –30.5 kJ/mol What is the overall DG'° for the following reaction? Phosphocreatine + ADP -> creatine + ATP

#Question id: 450

#Unit 1. Molecules and their Interaction Relevant to Biology

The DG'° values for the two reactions shown below are given.

Oxaloacetate + acetyl-CoA + H2O -> citrate + CoASH DG'° = –32.2 kJ/mol

Oxaloacetate + acetate    ->   citrate DG'° = –1.9 kJ/mol

What is the DG'° for the hydrolysis of acetyl-CoA?

Acetyl-CoA + H2O -> acetate + CoASH + H+

#Question id: 451

#Unit 1. Molecules and their Interaction Relevant to Biology

The standard reduction potentials (E'°) for the following half reactions are given.

Fumarate + 2H+ + 2e– -> succinate E'° = +0.031 V

FAD + 2H+ + 2e– -> FADH2 E'° = –0.219 V

If you mixed succinate, fumarate, FAD, and FADH2 together, all at l M concentrations and in the presence of succinate dehydrogenase, which of the following would happen initially?

#Question id: 452

#Unit 1. Molecules and their Interaction Relevant to Biology

E'° of the NAD+/NADH half reaction is –0.32 V.  The E'° of the oxaloacetate/malate half reaction is –0.175 V.  When the concentrations of NAD+, NADH, oxaloacetate, and malate are all 10–5 M, the “spontaneous” reaction is: