Chapter 10, Problem 1.1Q

Summary Introduction

To determine: The effects on growth of a homozygous knockout of enzyme 3 in the  amino acid biosynthetic pathway [A-B-C-D- amino acid] which were catalysed by Enzymes 1,2,3 and 4 respectively.

Introduction: The gene knockout is now a day becomes very important key point to study the gene impacts and its importance in the genetics.

Explanation of Solution

The below amino acid pathway is, in which at every step an enzyme is consumed to produce the next one:

$A_1\Rightarrow B_2\Rightarrow C_3\Rightarrow D_4\Rightarrow AminoAcid$

Since the above-mentioned pathway shows homozygous knocked out of enzyme 3, which supports One Gene One Enzyme hypotheses, in that case, the pathway stops after C, as there is no enzyme present which converts the C to D in the above pathway.

Summary Introduction

To determine: The means by which the points by these impacts be redressed.

Introduction: In heterozygous knockout one gene from the allele is knocked out while in homozygous both the genes from the same allele are knocked out.

Explanation of Solution

The below pathway is supported by one gene-one enzyme hypothesis. The enzyme 3 is absent after homozygous knocking out due to which the fourth step is not completed yet.

$A_1\Rightarrow B_2\Rightarrow C_3\Rightarrow D_4\Rightarrow AminoAcid$

Hence, knockouts of metabolic pathways are acquired as single genes, suggesting that one gene encodes one polypeptide. An organism can survive the homozygous knockout of the gene for an enzyme in a critical metabolic pathway if it is supplied with the metabolites required in later stages of the pathway.