2.1_DNA_structure_and_Function__1_

Group Presentations Requirements

• Individual Submission (Due Feb 13):

  • Names of the five students in the group.

  • Group Topic.

  • Three references from primary literature related to the topic.

  • Three preferred presentation dates from the group.

Overview of Group Presentations

• Learning Objective:

  • Utilize information from various sources to construct and communicate knowledge.

• Task:

  • Gather information on a current biological topic from research articles, texts, web, and other sources.

  • Analyze and synthesize the information for a class presentation.

Oral Presentation Grading Criteria

• Total Points: 75

  • Content (25 pts):

    • Substantive summary of important recent results (past 5 years) from scientific literature.

  • Appearance & Effectiveness of Slides (20 pts):

    • Slides should be organized, readable, and contain a balance of text and figures.

  • Presentation (30 pts):

    • All members participate in the presentation.

    • Team displays mastery of content and can answer questions.

    • 10 minute presentation with 5 minutes for questions.

DNA Structure and Function

• Base Pairing:

  • T-A (Thymine-Adenine)

  • C-G (Cytosine-Guanine)

Understanding DNA

• Function:

  • Acts as a recipe for biological information.

Key Discoveries (1952-1953)

• Watson & Crick:

  • Published the structure of DNA - double helix in February 1953.

• Nobel Prize (1962):

  • Awarded to Watson, Crick, and Wilkins for their discoveries.

Rosalind Franklin

• Contribution:

  • Created Photo 51 in 1952, providing crucial evidence for DNA structure.

DNA Structure

• Components:

  • Nucleotides (sugar, phosphate group, nitrogenous bases).

  • Double helix structure with complementary strands.

Packaging of DNA

• Hierarchy:

  • DNA double helix (2nm) ➔ Nucleosome ➔ 30 nm fiber ➔ Higher-order chromatin ➔ Chromosome (700nm).

Central Dogma of Biology

• Information Flow:

  • DNA ➔ mRNA ➔ Proteins.

• Key Processes:

  • Transcription: DNA to mRNA.

  • Translation: mRNA to Protein.

The Genetic Code

• Definition:

  • Rules translating DNA base sequences into amino acid sequences.

• Triplet Code:

  • Proposed by George Gamow as a 3-letter code encoding 20 amino acids.

Codon Table

• Explanation:

  • Codons consist of 3 nucleotides, each coding for a specific amino acid.

  • Example: UUU ➔ Phenylalanine, CUU ➔ Leucine.

Genes and Genetic Variation

• Definition of Genes:

  • Units of heredity located on chromosomal DNA, coding for proteins.

  • Encode phenotype, with only 1.5% of DNA coding for proteins.

• Mutations:

  • Changes in nucleotide sequences, affecting protein function.

Examples of Genetic Variation

• Single Base Substitution:

  • Sickle cell anemia resulting from a mutation in hemoglobin gene.

In-Class Question

• Purines:

  • Which nitrogenous bases are classified as purines?

  • Options: A. Uracil, B. Guanine, C. Thymine, D. Cytosine, E. All of these.

Final Tasks

• Homework Assignment:

  • Create a mind map of the lecture content with at least 10 nodes using a mind mapping tool.