Tag: expression of gene

Inactivation of RNA by using another RNA is called RNA interference(RNAi). It is used in pest control in tomato plant. It is a cellular defence method. It is applicable to eukaryotes only.

So, the correct option is ‘Eukaryotes’.

Lac-operon refers to the group of genes present in bacteria that are responsible for the metabolism of lactose. There are three genes called LacZ, LacY and LacA that code of beta-galactosidase, permease and transacetylase respectively. They have a common promoter, operator and a regulator gene.

A DNA segment that contributes to phenotype/function is called gene. In prokaryotes, the predominant site for control of gene expression is at Transcription level, where as in eukaryotes, control of gene expression occurs at transcription level, processing level, transport of mRNA, translation level.

So, the correct option is ‘Transcription intiations’.

In E.coli, a single circular, nacked dsDNA molecule act as a genetic material. It contains 64 genes and are grouped into 20 operons.

So, the correct option is ’64, 20’.

In eukaryotes, the translation process begins at the start codon AUG, which codes for the amino acid methionine.

Operon can be defined as DNA segment having a cluster of genes which are controlled by single promoter. It consists of operator gene and structural genes. The operator gene regulates the expression of structural genes by providing a binding site to transcription factor which in turn regulate the gene expression by altering the binding of RNA polymerase to the promoter region. A promoter is a DNA segment where transcription of a particular gene starts. The regulator genes code for transcription factor/repressor proteins that binds to operators or promoters and prevent RNA polymerase from transcribing RNA. The alteration in repressor proteins by inducers make them unable to bind DNA and allow RNA polymerase to carry out transcription. Thus regulator gene control the functioning of structural genes via operator gene. Option C is correct answer.

Promoter is a DNA segment that serves to initiate transcription of a particular gene. They are present upstream near the transcription start sites of genes. Regulator gene regulates the expression of structural genes by its protein product that are mostly transcription factors. These transcription factors bind to the operator region which is located just upstream the binding site of the RNA polymerase and hence, prevent the binding and transcription. Operator is a DNA sequence present between the promoter region and the first coding gene. This operator region serves as repressor protein binding site. The gene that codes for any RNA / protein product which do not serve as regulatory protein are known as structural genes. The lac Z lac Y and lac A genes in lac operon are the structural genes. Option B is the correct answer.

Operon can be defined as DNA segment having a cluster of genes which are controlled by single promoter. It consists of operator gene and structural genes. The operator gene regulates the expression of structural genes by providing a binding site to transcription factor which in turn regulate the gene expression by altering the binding of RNA polymerase to the promoter region. A promoter is a DNA segment where transcription of a particular gene starts. Ligase enzymes facilitate the joining of two DNA strand together by phosphodiester bonds. The regulator genes code for transcription factor/repressor proteins that binds to operators or promoters and prevent RNA polymerase from transcribing RNA. The alteration in repressor proteins by inducers make them unable to bind DNA and allow RNA polymerase to carry out transcription. Thus regulator gene control the functioning of structural genes via operator gene. Option D is correct answer.

• Growth hormone helps in amino acid uptake in all the tissues and also help in the transcription process in which DNA is converted into mRNA.
  
• GH also help in synthesis of protein hormone.
• It also helps to decrease protein catabolism.