Lab 6 - BIO100L

DNA Overview

• DNA Structure

  • Double helix structure resembling a twisted ladder.

  • Composed of two strands held together by hydrogen bonds.

DNA Fingerprinting

• Method for analyzing DNA fragments to identify individuals.

• Used in crime scene investigations and paternity tests.

  • Not actual handprints; metaphor for uniqueness.

• Samples can come from hair, blood, or skin.

Announcements

• Reminder to wash hands before leaving the lab.

• Exam: Next week covering Diffusion/Osmosis, Photosynthesis/Cellular Respiration, and DNA.

• Discovery Center information.

Presentations Page

• A placeholder for upcoming presentation details.

Investigation Details

• Investigation 3: DNA Fingerprinting Gel

  • Wells for loading DNA samples from crime scene and suspects.

  • Use of dye to visualize DNA chunks during gel electrophoresis.

• Investigation 1: DNA Structure and Replication

  • Group activity to simulate DNA replication, emphasizing precision.

• Investigation 2: DNA Fingerprinting Simulation

  • Groups simulate DNA fingerprinting with different suspect samples.

  • Ensure proper counting of DNA fragments.

Micropipette Usage

• Sterile tips must be used.

• Hold the pipette correctly to transfer liquids.

• Press down to draw liquid and push all the way to expel.

DNA Components

• DNA is made of nucleotides:

  • Composed of phosphate, a sugar molecule, and a nitrogenous base.

• Four nitrogenous bases: Adenine, Guanine, Cytosine, Thymine.

  • A pairs with T, and C pairs with G.

DNA Characteristics

• Antiparallel Structure

  • Strands run in opposite directions meeting in the middle.

• Double helix can exceed 3 billion base pairs in length.

Chromosome Information

• Chromosomes

  • Tightly wound DNA + protein that carries genetic information.

  • Formed from chromatin during cell division.

• Humans have 23 pairs of chromosomes (46 total).

• Diploid vs. Haploid

  • Diploid (2n): Two copies of each chromosome (found in somatic cells).

  • Haploid (1n): One copy of each chromosome (found in gametes).

DNA Replication Process

• Occurs during interphase before cell division.

• Enzyme DNA Helicase unwinds the double helix.

• New strands are synthesized using original strands as templates (semi-conservative replication).

Gel Electrophoresis

• Technique for separating DNA fragments based on size/length.

• Smaller fragments move faster through the gel, creating distinct bands for comparison.

• Electric current applied to facilitate movement towards positive electrode.

Restriction Enzymes in DNA Fingerprinting

• Cut DNA at specific sequences to allow analysis of fragments.

• Examples include EcoRI, BamHI, and HindIII, producing either sticky or blunt ends.

• Useful for creating distinct DNA profiles for fingerprinting.

Notes on Laboratory Practices

• Follow lab safety and procedural guidelines during investigations.

• Coordinate with team members during group activities for effective collaboration.