Human Body

DNA, RNA and Protein (Structure, Composition and Function)

DNA IS A DEOXYRIBONUCLEIC ACID. RNA IS A RIBONUCLEIC ACID.

PROTEIN IS A BUILDING BLOCK OF LIFE, WHICH CONSISTS OF AMINO ACIDS.

We Need Nucleic Acids!

• DNA contains genes, the information needed to synthesize functional proteins and RNAs.

• DNA contains segments that play a role in regulation of gene expression (Transcription and Translation level; promoters, operators, etc.)

• Ribosomal RNAs (rRNAs) are components of ribosomes, playing a role in protein synthesis.

• Messenger RNAs (mRNAs) carry genetic information from a gene to the ribosome.

• Transfer RNAs (tRNAs) translate information in mRNA into an amino acid sequence.

• RNAs have other functions, and can in some cases perform catalysis.

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Figure 1: RNA and DNA.

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Figure 2: Structures of DNA.

Figure 3: Structure of RNA.

Nucleotides and Nucleic Acids: Nucleotides are the building blocks of nucleic acids.

Nucleotides have three characteristic components:

A nitrogenous base (Pyrimidines or Purines), A pentose sugar and A phosphate group.

1. The Pyrimidine and Purine Bases (Major Bases in Nucleic Acids)

• The bases are abbreviated by their first letters (A, G, C, T, U).

• The purines (A, G) occur in both RNA and DNA

• The pyrimidine C occurs in both RNA and DNA, but

• T occurs in DNA, and

• U occurs in RNA.

[pic]2. Pentose Sugar: Ribose vs. Deoxyribose.

• An important derivative of ribose is 2'-deoxyribose, or just deoxyribose, in which the 2' OH is replaced with H.

• Deoxyribose is in DNA (deoxyribonucleic acid)

• Ribose is in RNA (ribonucleic acid).

• The sugar puckers in DNA (C-2' endo) and RNA (C-3' endo) are different (Why?)

• The 2’-OH and pucker have a big effect on the double helical structure!

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3. The Phosphate group

A nucleoside + one or more phosphoryl groups is called a nucleotide....