Answer to Question #164947 in Genetics for Sam

Question

Explain the nucleotide structure and main features of the following nucleic acids:

• DNA – stages and enzymes involved in DNA replication

• RNA – mRNA, tRNA, rRNA, siRNA

Answer 1

There are three main steps to DNA replication: initiation, elongation, and termination. In order to fit within a cell's nucleus, DNA is packed into tightly coiled structures called chromatin, which loosens prior to replication, allowing the cell replication machinery to access the DNA strands.

Messenger RNA (mRNA) carries the instructions from the nucleus to the cytoplasm. mRNA is produced in the nucleus, as are all RNAs.The other two forms of RNA, ribosomal RNA (rRNA) and transfer RNA (tRNA), are involved in the process of ordering the amino acids to make the protein. rRNA becomes part of the ribosome, which is the site of protein synthesis, and tRNA brings an amino acid to the ribosome so it can be added to a growing chain during protein synthesis. There are numerous tRNAs, as each tRNA is specific for an amino acid.