DNA Isolation and Structure Lab 4

DNA Isolation, Structure, and Technology Lab 4

• Objectives: Understand DNA isolation from plants, DNA structure, DNA fingerprinting processes, DNA molecule construction, and base pairing. Demonstrate DNA fingerprinting using diagrams.

Introduction to DNA Structure

• DNA is a double-stranded molecule composed of nucleotides.
• Each nucleotide contains a sugar (deoxyribose), a phosphate group, and a nitrogenous base.
• Four nitrogenous bases: adenine, thymine, guanine, and cytosine.
• Adenine pairs with thymine, and guanine pairs with cytosine.
• The alternating sugar-phosphate groups form the sides of a DNA "ladder."
• Nitrogenous bases form the rungs of the ladder.
• The ladder is twisted into a helix shape.

DNA Function

• DNA is the genetic material in the nucleus of cells.
• DNA, along with attached proteins, makes up chromosomes.
• Eukaryotic cells have homologous chromosome pairs.
• Humans have 23 pairs of homologous chromosomes (46 total in diploid cells.).
• DNA replication occurs during interphase of the cell cycle.
• The process involves making an exact copy of DNA using enzymes and following base-pairing rules.
• DNA replication is semi-conservative, meaning each new DNA molecule includes one original strand and a newly synthesized strand.

DNA Isolation Procedure

• Strawberries are a good source for DNA extraction due to their soft cell walls and multiple copies of DNA.
• Procedure involves smashing strawberries in a Ziploc bag and adding a lysis buffer.
• Mixture is filtered through cheesecloth into a beaker.
• Ethanol is carefully poured into a test tube with the strawberry extract.
• A white DNA layer will form at the ethanol/extract interface.