Question

1) Describe the process and steps involved in the production of a protein from a DNA blueprint.

Answer 1

The central dogma of life:

DNA ------> RNA -----> Protein

DNA ------> DNA: Replication: It is mediated by DNA polymerase

DNA ------> RNA: Transcription: It is mediated by RNA polymerase

RNA -----> Protein: Translation: It is mediated by the ribosome, tRNA, and amino acids.

In a human cell, DNA serves as the genetic material. It contains all the information for the proper growth and development of the cell. DNA codes for RNA which contains coding information to specify a protein sequence. A protein is the structural and functional component of a cell. All the cells in the body contain almost identical genome sequence (except for few immune system cells). However, all cells do not express all the genes all the time. Each tissue type expresses a specific set of genes at specific time period i.e. temporal and spatial expression. Such genes are known as tissue-specific genes. These tissue-specific genes are responsible for different structures and functions of different tissues in our body. The tissue-specific gene expression is mediated by epigenetic as well as transcriptional gene regulation.

Steps in eukaryotic gene expression:

i. Transcription

ii. Post-transcriptional modifications (A-tailing, splicing, and capping)

iii. Translation

iv. Protein folding

v. Post-translational modifications

vi. Protein localization

See image for a eukaryotic gene structure.

DNA codes for a mRNA which contains triplet codons. Each triplet codon specifies an amino acid.

For example,

DNA sequence: 5'-ATGGGGGACACGATCGTCCGTGACAACAAATAG-3'

mRNA sequence: 5'-AUGGGGGACACGAUCGUCCGUGACAACAAAUAG-3'

Protein sequence: NH2-MGDTIVRDNK-COOH

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