Terminology and Phrases:

function of nucleic acids, DNA, RNA, deoxyribonucleic acid, ribonucleic acid, nucleotide, 3 parts of a nucleotide, 2 types of bases, general form of nucleotide, double helix, hydrogen bonds, which bases bond, purine, pyrimidine, adenine, guanine, cytosine, thymine, uracil, differences in DNA and RNA, function of RNA, ribosomes, replication, helicase, DNA polymerase, template, cell division, mutations

1. What is a nucleic acid?

  • One of our four macromolecules
  • Monomers are nucleotides
  • Two nucleic acids are DNA and RNA (deoxyribonucleic acid and ribonucleic acid)

2. Purpose of DNA

  • Store and pass along hereditary information
  • Carry the codes to make proteins for the cell

3. Chromosomes and Chromatin

  • DNA is organized into chromosomes; when the cell is not dividing, the chromosomes appear as stringy chromatin, which is DNA wrapped around proteins.
  • Notice the histone proteins around which DNA is wrapped several times.
  • A human has 46 chromosomes; around 6 feet of DNA is inside each cell nucleus.

Chromatin vs. a Condensed Chromosome

4. Genes

  • A gene is a section of a chromosome (DNA) which codes for a characteristic, such as the gene for curly hair, the gene for brown eyes, and the gene for attached or unattached earlobes.
  • Genes can code for physical characteristics, chemical properties, and behavior.

Below image of DNA credited to: http://cancergenome.nih.gov/media/DNAKit_illustration_image.jpg
Below image of DNA and RNA credited to: http://www.accessexcellence.org/RC/VL/GG/images/rna2.gif
external image rna2.gif
The energy source for the cell is actually composed of a 5- Carbon sugar, base, and THREE phosphate groups!!!
external image ATP.gif

5. The Nucleotide: The Monomer of a Nucleic Acid

Below image of nucleotide credited to: http://www.msu.edu/course/isb/202/ebertmay/drivers/nucleotide.jpg
external image nucleotide.jpg
  • A nucleotide is composed of a phosphate group, a sugar, and a base.
  • The sugar and phosphate portions of the nucleotide make up the sides of the helix.
  • The bases of a nucleotide connect across the middle of the DNA helix.
  • Hydrogen bonds hold the bases together.
  • A purine base must always pair with a pyrimidine base in DNA. (adenine to thymine, cytosine to guanine) Purines have two rings, but pyrimidines have only one.
Below image credited to: http://www.nvo.com/jin/homepage20/

Below image of DNA credited to: http://publications.nigms.nih.gov/thenewgenetics/images/ch1_nucleotide.jpg
external image ch1_nucleotide.jpg

6. The Differences in DNA and RNA

  • DNA contains the bases adenine, thymine, guanine and cytosine. RNA contains uracil instead of thymine.
  • DNA typically remains in the nucleus. RNA can leave the nucleus and function in the cytoplasm.
  • DNA is a double stranded helix, but RNA is single stranded.
  • There is only one type of DNA in a cell but potentially three types of RNA (mRNA, tRNA, rRNA).
  • DNA contains the sugar deoxyribose. RNA contains ribose.

7. The Three Types of RNA:

  • mRNA- (messenger RNA) carries DNA's message to ribosome
  • tRNA- (transfer RNA) transfers amino acids to ribosome
  • rRNA- (ribosomal RNA) makes up the ribosome


Human Genome
http://homepage.mac.com/wildlifeweb/cyto/human/HSA550.gifHuman Karyotype