Question

escribe the central dogma theory and explain in detail the two main processes that are involved. Is this theory held true for all genes? Why or why not? Include: transcription, translation, mRNA, tRNA, rRNA, ribosomes, amino acids, coding strand, template strand, RNA polymerase

Answer 1

central dogma:

it was the first describes by Francis Crick in 1958.

the central dogma is a process, explains the flow of genetic information from DNA to RNA and RNA to proteins. in this process once genetic information transfer to form protein, it is impossible transferred back from proteins to DNA or nucleic acid.

DNA can not directly code for protein hence it passes on the information to an RNA molecule from which protein synthesized. the process of DNA converted into a functional product is called gene expression.

in central dogma, all genes are involved in transcription but not all genes are involved in translation because some provide instructions to the formation of functional RNA molecules.

gene expression is divided into two steps, they are

1. transcription, 2. translation.

transcription:

it is the first step of gene expression. transcription involves the synthesis of the RNA molecule from the template strand.

DNA is a double-stranded, but RNA is single-stranded, it means only one strand involves in transcription.such as the strand that contains information for the synthesis of RNA is called as template strand or antisense strand. the other strand is a complementary strand is called coding strand or sense strand since RNA obtained during transcription is similar to a coding strand.

RNA polymerase is involved in transcription of all genes, it does not recognize the gene but recognizes the specific sequences nothing but promoter regions and bind to specific regions , then unwind the gene, copy the gene accurately and should recognize the termination signals present at end of the gene.

in prokaryotes only one type of RNA polymerase involved but in eukaryotes, there are 3 types of RNA polymerases are involved in transcription they are

1. RNA polymerase 1 - involved transcription in ribosomes RNA (rRNA)

2. RNA polymerase 3- involved transcription in transfer RNA (tRNA)

3. RNA polymerase 2- involved transcription in protein-coding genes.(mrna)

both RNA polymerase 1 and 3 involved only transcription of genes that are not involved in translation.

translation: the final step of gene expression

it is involved the conversion of mRNA to proteins, codons sequences in the mRNA converted to form aminoacids. ribosomes are involved in the build new proteins from chains of aminoacids.