Nucleic Acids

Monomer of nucleic acid

Nucleotide

Three parts of a nucleotide

A phosphate group, a five-carbon sugar (deoxyribose in DNA and ribose in RNA), a nitrogenous base.

Nitrogen bases in DNA

Adenine (A), Thymine (T), Cytosine (C), Guanine (G)

Characteristics of purines

Nitrogenous bases characterized by a two-ring structure, larger than pyrimidines.

Examples of purines

Adenine (A) or Guanine (G)

Characteristics of pyrimidines

Nitrogenous bases with a single-ring structure, smaller than purines.

Examples of pyrimidines

Cytosine (C), Thymine (T), or Uracil (U)

How is the DNA backbone created?

Phosphate group of one nucleotide attaches to the sugar of another nucleotide (at the 3’–hydroxyl position).

Type of bond in the DNA backbone

Phosphodiester bonds.

Function of RNA

Transfers genetic information in DNA to be read at ribosomes.

Three forms of RNA

mRNA, tRNA, rRNA.

mRNA description

Complementary copy of DNA strand with protein instructions written in codons (linear molecule).

tRNA description

Brings proper amino acids from cytoplasm to ribosome during translation (looped molecule).

rRNA description

Provides location to combine amino acids to make proteins, creates subunits of ribosome.

Function of DNA

Store genetic material for protein production.

Hershey Chase Experiment

Used radioactively labeled sulfur and phosphorus in a phage virus to show that DNA holds genetic information.

Rosalind Franklin's contribution

Used X-ray diffraction to show DNA had a helical structure.

Watson and Crick's findings

Created the correct structural model of DNA, showing double helix and antiparallel nature of DNA.

What holds the nitrogen bases together?

Hydrogen bonds.

Chargaff’s rule

Complementary bases are found in the same amount in DNA; knowing one base percentage allows you to determine the others.

Importance of base pairing in the genetic code

Allows genetic information to be replicated and expressed as proteins.