Question

Define the following:

Promoter

tRNA

Exons

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Answer 1

Answer:

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Promoter– The promoter serves as the binding site for RNA polymerase for transcription. It helps in transcription initiation.

tRNA– tRNA or transfer RNA is involved in the translation of proteins. It reads the genetic code on the RNA and transfers specific amino acids to mRNA on the ribosomes.

Exons– Exons are the coding regions present in a DNA sequence in eukaryotes.

Answer 2

Answer:

(a) Promoter :------- In genetics, a promoter is a region of DNA that leads to initiation of transcription of a particular gene. Promoters are located near the transcription start sites of genes, upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long.

(b) tRNA :-------- A transfer RNA molecule is used in translation and consists of a single RNA strand that is only about 80 nucleotides long, containing an anticodon on the other end; the anticodon base-pairs with a complementary codon on mRNA and (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length, that serves as the physical link between the mRNA and the amino acid sequence of proteins.

tRNA does this by carrying an amino acid to the protein synthetic machinery of a cell (ribosome) as directed by a 3-nucleotide sequence (codon) in a messenger RNA (mRNA).

As such, tRNAs are a necessary component of translation, the biological synthesis of new proteins in accordance with the genetic code.

(c) Exons :------- An exon is any part of a gene that will encode a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term exon refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts.