DNA is genetic material. This fact was proved by Hershey and Chase. They did an experiment with bacteriophages in 1952. They labeled proteins and DNA by radioactive material. Due to this experiment that radioactively labeled DNA entered the host cell not the protein. This discovery supported the theory that DNA is radioactive material.
What is DNA and RNA composed of ?
DNA and RNA strands are called polynucleotides. Nucleotide is the basic unit. It's composed of phosphate group, sugar (ribose for RNA, deoxyribose for DNA) and nitrogenous base. There are 5 types of nitrogenous bases : Thymine, cytosine, adenine, guanine (these four can be found in DNA) and uracil (instead of Thymine there's an uracil in RNA).
How is DNA expressed ?
To have the genetic information expressed DNA must go through process of transcription and translation. During transcription DNA is transcribed into RNA molecule. Translation then translated those molecules into polypeptide chain.
Diagram :
This diagram shows a structure of DNA. Double-stranded helix and it also shows base pairing. with hydrogen bonds.
5facts:
DNA was proved to be genetic material in 1952 by Hershey and Chase.
Thymine (Uracil) pairs only with Adenine.
Guanine pairs only with Cytosine.
Watson and Crick were first to create the model of DNA.
Thymine and Cytosine are called Pyrimidines and Adenine and Guanine are called Purines.
Key terms :
bacteriophages - bacterial viruses
nucleotides - chemical units composed of nitrogenous base, phosphate group and sugar
double-helix - presence of two strands
semiconservative model - half of the parental DNA is maintained in each daughter molecule
DNA polymerase - unravels the DNA strand
DNA ligase - links the DNA strands back together
transcription - transfer of genetic information from DNA into RNA molecule
translation - transfer of the information in the RNA into a protein
genetic code - set of rules giving the correspondence between codons in RNA and amino acids in proteins
promoter - specific binding site for RNA polymerase
Video:
Summarize :
Chapter 10 give us an overview of the history of discovering the DNA and also the composition as well as its function and the way it functions, replicates and expresses genes.
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