Question

In humans, there are about 200 different types of cells. Why are your liver cells different from skin cells, or neurons, or muscle cells? During development, each cell accumulates different mutations changing their DNA They produce the same proteins but some of those proteins are denatured in each cell They have different DNA and thus, each cell produces different proteins They produce the same kind of proteins but not all proteins are active in each cell They have the same genes, but a different set of genes expressed in each cell

Answer 1

Answer 1: option (5) is the correct answer. Each cells have the same genes, but a different set of genes expressed in each cell.

DNA is the hereditary material in humans and almost all other organisms and almost every cell in an individual’s body has the same DNA. Our body is composed of many different types of cells. Cells of different organs are different from each other. Question is what makes them different from each other? The answer is lies in the way each cell deploys its own genome and also known as epigenetics. Epigenetics plays the key role in controlling the how much a gene gets read. Epigenetics leads some cells to read certain genes or combination of genes more, while others will read those same genes less. This difference dictates cellular morphology and function that give us the wide variety of cell types in our bodies – even though they all have the exact same DNA.

Answer 2: option (1) is the correct answer. Prokaryotic mRNA goes through multiple modifications before translation is the False statement.

Answer 3: option (2) is the correct answer. Human DNA contains introns but bacteria do not do splicing.

Explanation for answer 2^nd and 3^rd:

A transcription result in the formation of the RNA and it is the 1^st step in gene expression. It is a key point for many genes regulation. In transcription, one of the two DNA strand act as a template for the synthesis of RNA. In eukaryote expression of genes involves many steps, for example transcription takes place in nucleus and then RNA processing happens. RNA processing includes many steps like- splicing, capping, and addition of a poly-A tail to an RNA molecule so that it can exit from the nucleus for the translation. Through alternative splicing different mRNAs (mature RNA) can be made from the same pre-mRNA.

Whereas, prokaryotic lacks any membrane bound organelles and that is the reason in prokaryotic transcription occurs in the cytoplasm. Prokaryotic genes lake introns and it does not need any post transcription modification and directly result in the mRNA. This is the one of the reason that prokaryotic transcription and translation can occur simultaneously in cytoplasm.