Question

part a: Compare advantages and disadvantages of metagenomics and genomics. What is meant by the term “metagenomics”?

part b : Describe the process of negative control of gene expression. Explain the role that repressor proteins play in this process.

part c Describe the two types of protein components involved in a two-component regulatory system. What are their roles?

part d Describe the SOS response.

Answer 1

Part a: Metagenomics: Metagenomics is a molecular tool/bioinformatics tool used to generate a metagenome. It involves sequencing of all DNA acquired directly from environmental samples and mapping them to a reference database. Metagenomics allows discovering new genes or completing genomes from the community of microorganisms, without the necessity of obtaining pure cultures

Advantages and disadvantages of metagenomics and genomics

Advantages of metagenomics

i) It allows for the discovery and study of microbial genomes without the necessity of obtaining pure cultures.

ii) To analyze the genomic composition of an uncultured microorganism present in the environment.

iii) To study the diversity patterns of microorganisms.

iv) To study and analyze novel genes coding for the metabolic pathways, secretory, regulatory and signal transduction mechanisms.

v) Construction of a gene or complete genome of an organism.

vi) It is used to detect novel pathogens in medicine and contributes for the treatment of infectious disease.

vii) It is useful in to industrial enzymes and bioactive molecules in agriculture field.

viii) It is used to analyze certain novel heavy metal and radionucleotide remediating bacteria from the polluted environments.

Disadvantages of metagenomics

i) Massive sequencing of the entire genome of an organism is very expensive.

ii) Assembling is impossible in high diversity communities

iii) To study the low abundance members in an environment is difficult.

iv) Chimeric sequences are produced.

Genomics: Genomics is an interdisciplinary tool that concerns the sequencing and analysis of an organism's genome. It focuses the structure, function, evolution, mapping and editing of genomes. A genome is the complete set of DNA, including all of its genes.

Advantages of genomics

i) In medical field it is used to make genetic diagnosis of disease and treatment.

ii) Genomics is the basis for developing a variety of products to prevent diseases.

iii) It is used to detect single gene errors.

iv) In agriculture field it is used to improve the quality and quantity of crop yields.

Disadvantages of genomics

i) Cannot understand a person's risk for diseases.

ii) Increase anxiety and stress.

iii) By genome sequencing the role of genomes is incompletely understood

Part b: Negative control of gene expression: Negative control of gene expression involves the binding of a repressor protein to the operator which prevent the transcription of the genes on the operon. Thus the operon will be expressed when the repressor in inactivated. When the repressor protein binds to the operator, it prevents the enzyme RNA polymerase from binding to the promoter and the transcription of the operon. When the repressor protein is bound to the operator, it prevents transcription and there is no mRNA production.

Part c: Two-component regulatory systems: The two types of protein components involved in a two-component regulatory system are sensor kinase and response regulator proteins, carry out signal transduction in prokaryotic and eukaryotic microorganisms, as well as plants.

Kinase senses specific environmental stimulus by differential expression of target genes. Response regulator proteins act as phosphorylation mediated switches, which sense specific environmental stimuli and turning on and off cellular responses.

Part d: Miroslav Radman was described SOS response in 1975 (SOS - save our ship or save our souls). It is a massive cellular process in which the cell cycle is arrested and the DNA repair and cause mutation.