This is a genetics question. Please show ALL work and the correct answer in orde

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This is a genetics question. Please show ALL work and the correct answer in order to be rated. Thanks!

7B. Decades ago before large-scale DNA sequencing had been done, most geneticists would probably have expected a typical genome to consist mostly of conventional protei coding genes. Summarize how genomes actually differ that naive expectation. 7c A few decades ago RNA was known to play three different and essential roles in gene expression. Name those three, and summarize those that have been discovered since then. 7D. While only a very small fraction of most animal and plant genomescodes for proteins, numerous non-coding DNA sequences are now known to have essential genetic roles. List these and give a brief (1-2 sentence) summary of what they do.

Explanation / Answer

7B. Most of the eukaryotic genome consists of non-coding DNA (=DNA that do not code for proteins). For example, the coding DNA in humans consists of less than 2% of the 3.2 giga-bases of genome. Further, each gene in eukaryotes are interrupted by multiple, long non-coding DNA, called introns (the coding parts of a gene is called exon.). Exons constitute just 1% of the human genome. Thus, almost 99% of the human genome does not code for protein.

Further, almost 58% of the human genome is represented by repetitive sequences, out of which, 45% represents the transposable elements, and rest 13% are just repetitive sequences.

Thus, the eukaryotic genome is not just an array of conventional genes. They are just a tiny part of a huge genome sequences.

7C. There are three major types of RNAs –

mRNA (Messenger RNA) – The RNAs that gets transcribed from a gene and codes for proteins.

rRNA (Ribosomal RNA) – The RNAs that constitute a major part in the structure of ribosomes

tRNA (Transfer RNA) – RNAs which bind to amino acids and transfer them to a growing chain of proteins.

But, in the last decade, several types of non-coding RNAs have been discovered to carry out a series of vital functions. Some of these are –

Catalytic RNAs (Ribozymes) – Catalytic RNAs catalyse a chemical reaction, much similar to the way enzymes do. For example, the trans-peptidyl reaction (linking one amino acid to another during protein synthesis) is carried out by a ribozyme. Another very common example is the ribozyme action of the spliceosome that carries out splicing of introns to join exons.

Small non-coding RNAs – These are short double stranded and single stranded RNA molecules that bind to mature RNAs to silence the translation of it. This phenomenon is called RNA interference (RNAi). Examples are miRNA (micro-RNA) and snRNA (small nucleolar RNA).

7D. Roles of non-coding DNA –

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