Structure and Function of DNA and RNA

Welcome to the Applied Microbiology course at Strom Thurmond High School in Johnston, South Carolina.  The students in this class are juniors and seniors who have successfully completed at least one chemistry course.  The teacher is Sandra Gladden, who has taught various science classed at STHS since 1986.

We are now beginning our study of viruses and need to review the structures and functions of DNA and RNA.
 
 

DNA

deoxyribonucleic acid

RNA

ribonucleic acid
DNA is used to transfer information from one generation to another. RNA is used to take the information from  DNA and use it to make proteins.  Proteins control many of the chemical reactions that occur in cells.
The structure of a DNA molecule is called a double helix (a twisted ladder).  The two halves of the DNA "ladder" are long strings of building blocks called nucleotides.  RNA molecules are single-stranded polymers of nucleotides also.  These molecules could be describes as "half-ladders."
Each nucleotide in a DNA molecule consists of three parts, a sugar (deoxyribose), a phosphate group,  and a nitrogen base. Each nucleotide in an RNA molecule consists of three parts, a sugar (ribose), a phosphate group, and a nitrogen base.
The sides of a DNA "ladder" consist of alternating sugar and phosphate groups.  Each "rung" consists of nitrogen base pairs. The side of an RNA "half-ladder" consists of alternating sugar and phosphate groups,  Each half-rung consists of one nitrogen base.
In DNA there are four different kinds of nitrogen bases, adenine (A), guanine (G), cytosine (C) and thymine (T). In RNA there are four different kinds of nitrogen bases, adenine (A), guanine (G), cytosine (C), and uracil (U).
In DNA "rungs," adenine always pairs with thymine and cytosine always pairs with quanine. When DNA is used as a template to produce RNA (during transcription), guanine always pairs with cytosine.  Thymine on the DNA pairs with adenine on the RNA. But adenine on the DNA pairs with uracil on the RNA.

 
 

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Find information about viruses on the www.


http://rpsec.usca.sc.edu//Classwork/731sp2002/Lesson/Gladden/gladden2.html
       (January, 2002)
The views expressed here are not necessarily those of the University of South Carolina.