Chapter 20, Problem 20.5PS

(a)

Summary Introduction

To determine: Whether the statement, “The rate of glucose consumption per cell is approximately the same after time t as before.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E. coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(b)

Summary Introduction

To determine: Whether the statement, “The rate of lactose consumption is higher after time t than before.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(c)

Summary Introduction

To determine: Whether the statement, “The intracellular cAMP level is lower after time t than before.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(d)

Summary Introduction

To determine: Whether the statement, “Most of the lac operator sites have lac repressor proteins bound to them.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(e)

Summary Introduction

To determine: Whether the statement, “Most of the catabolite activator proteins exist as CAP-cAMP complexes.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(f)

Summary Introduction

To determine: Whether the statement, “Most of the lac repressor proteins exist as repressor-glucose complexes.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(g)

Summary Introduction

To determine: Whether the statement, “The rate of transcription of the lac operon is greater after time t than before.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.

(h)

Summary Introduction

To determine: Whether the statement, “The lac operon has both CAP and the repressor protein bound to it.” is true of the cells transferred to the medium L (L), true of the cells transferred to the medium G (G), true of the cells transferred to the medium B (B) or true of none of the cells (N).

Introduction: A culture of E.coli cells growing on medium B containing both lactose and glucose is taken. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose; 33% of the cells are transferred to medium G, which contains glucose but not lactose; and the rest 33% of the cells are left in medium B.