Nucleic Acids Overview

Nucleic Acids

• Nucleic acids are large molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus.
• The building blocks of nucleic acids are nucleotides.
• A nucleotide consists of a 5-carbon sugar (pentose), a nitrogenous base, and a phosphate group.
• Nucleotides link together via dehydration synthesis to form long chains, creating nucleic acids.

Learning Objectives

• Define nucleic acid
• Identify the two classes of nucleic acid
• Compare and contrast DNA and RNA
• Explain protein synthesis

Two Classes of Nucleic Acids

• Deoxyribonucleic acid (DNA)
• Ribonucleic acid (RNA)

Deoxyribonucleic Acid (DNA)

• DNA is the genetic material of cells, controlling cell activities.
• DNA's nucleotides contain deoxyribose sugar and the nitrogenous bases: adenine, thymine, cytosine, and guanine.
• DNA consists of two nucleotide chains joined by hydrogen bonds, forming a double helix.

Ribonucleic Acid (RNA)

• RNA is a single-stranded nucleotide chain.
• RNA's nucleotides contain ribose sugar and the nitrogenous bases: adenine, uracil, cytosine, and guanine.
• RNA's function is protein synthesis within cells.

Comparison of DNA and RNA

Protein Synthesis

• DNA holds the instructions for protein production within cells.
• Protein synthesis occurs in two steps:
  • Transcription
  • Translation

Transcription

• DNA separates, and mRNA is created as a complementary copy of a segment of DNA.
• mRNA carries the information from DNA to the cytoplasm where translation takes place.
• mRNA leaves the nucleus.

Translation

• mRNA moves to a ribosome, which is the site of protein synthesis in the cells.
• Transfer RNA (tRNA) molecules bring amino acids to the ribosome.
• The ribosome reads the mRNA's codons, and tRNA delivers the specified amino acids.
• Amino acids bond to form a polypeptide chain, the precursor to a protein.