Module 10 Lecture Notes

Exam Overview

• Upcoming Exam 3
  • Covers Chapters 10-17
  • Includes topics such as genetics problems, replication, transcription, and translation.
  • Key problems:
    • Monohybrid, incomplete dominance, sex-linked, blood type, and dihybrid questions.
    • Phenotype ratios and genotypic/phenotypic ratios.

Key Concepts and Practice Areas

Genetics Problems

• Blood Type Problems
  • Example: Mom with blood type O, Dad with blood type B.
  • Determine genotypic and phenotypic ratios of offspring.
  • Calculate probabilities (e.g., probability of having a child with blood type B).
  • Blood type O genotype involves recessive alleles, blood type B has heterozygote form.
• Sex-Linked Problems
  • Example: Mom as a carrier for red-green color blindness.
  • Males are hemizygous, not carriers.
  • Focus on X-linked recessive problems for the exam.

Replication

• Based on Chargaff's Rules:
  • A pairs with T
  • C pairs with G
  • Short answer question will involve replicating a given DNA strand.
  • Flip the ends: 5' to 3' orientation is crucial.

Transcription and Translation

• Transcription: DNA to Messenger RNA (mRNA)
  • Use RNA Polymerase and apply Chargaff’s rule with U replacing T (A pairs with U).
• Translation: mRNA to Protein
  • Use the genetic code table to translate mRNA into amino acids.
  • Always start with Methionine (AUG codon).
  • Understand redundancy in codons.

Practice Problems

• Practice genetics and replication problems from previous modules especially Module 8.
• Use scratch paper during exams and understand partial credit systems.

DNA Structure and Enzymes

• Double helix, anti-parallel structure.
• Nucleotide composition: sugar, phosphate group, nitrogenous base.
• Enzymes involved in replication, transcription, and translation.

Genetic Coding and Mutation

• Discussed mutations like frame shift (addition/deletion of bases) and their impacts.
• Sickle cell anemia as an example of a single base change affecting function.
• Importance of start (AUG) and stop codons in protein synthesis.

Historical Experiments

• Beadle and Tatum: Neurospora crassa experiments
  • Radiation induced mutations to study enzyme synthesis.
  • Supported the one gene-one enzyme hypothesis.

Gene Expression in Prokaryotes vs Eukaryotes

• Prokaryotes:
  • Continuous transcription and translation due to lack of nucleus.
  • Operons regulate gene expression (e.g., Lac operon).
• Eukaryotes:
  • Nuclear envelope allows for RNA processing (splicing, capping, tailing).
  • Alternative splicing allows for multiple protein products from a single gene.

Exam Preparation

• Review genetic problems, replication techniques, transcription, and translation.
• Practice using genetic code tables and understanding codon assignments.
• Prepare for questions on both lab and lecture exams; they reinforce each other.