In-depth notes for BIOL 1106 Lab Manual

Lab 13: Mendelian Genetics and Chi-Square Calculations

• Genetics Definition: Study of heredity, primarily focused on how traits are passed from parents to offspring.

• Gregor Mendel: Austrian monk who established the foundational laws of heredity using pea plant experiments.

• Heredity Basics:

  • Genes: Units of heredity; each individual possesses two copies for traits, one from each parent.

  • Alleles: Different forms of a gene; represented by letters:

  • Dominant Alleles: Represented by capital letters (e.g., T).

  • Recessive Alleles: Represented by lowercase letters (e.g., t).

• Genotype vs. Phenotype:

  • Genotype: Genetic makeup represented by letter combinations (e.g., AA, Aa, aa).

  • Phenotype: Physical expression of the trait (e.g., tall, dwarf).

Monohybrid Cross Examples:

1. Heterozygous Tall Pea Plant: Genotype = Aa (T = tall, t = dwarf).

2. Genotypic Ratio for Two Heterozygous Parents:

   • Expected ratios: 1:2:1 (1 AA, 2 Aa, 1 aa).

3. Phenotypic Ratio for Two Heterozygous Parents:

   • Expected ratios: 3:1 (3 tall: 1 dwarf).

Procedure 13.1: Monohybrid Cross of Pennies

1. Genotypes of Pennies:

   • Heads (dominant): P

   • Tails (recessive): p

   • Heterozygous Min. Genotype: Pp.

2. Expected Genotypic Ratio:

   • Upon crossing two pennies, expected ratios to be calculated.

3. Data Observation:

   • Record outcomes of 50 flips.

4. Chi-Square Analysis:

   • Chi-square formula: $X^2 = \sum \frac{(Obs.-Exp.)^2}{Exp}$

5. Degrees of Freedom: C - 1 (C = 3 categories: PP, Pp, pp).

Chi-Square Procedure Analysis:

1. Degrees of freedom using observed and expected (total counts).

2. Probability Range: Determine using the chi-square table results.

3. Evaluate if the data supports the hypothesis based on calculated results.

Additional Procedures: Corn Kernel Crosses and Dihybrid Crosses

• Procedure 13.2: Analyze corn kernels’ color:

  • Use T pin to identify kernel distribution between purple and yellow.

  • Report results for statistical evaluation of phenotypes.

• Dihybrid Cross Methodologies:

  • Assessing interactions between two traits (e.g., color and texture) amongst different coins or corn samples.

Lab 14: Human Genetics

• Cytogeneticists: Study human chromosomes using staining techniques for diagnostic purposes.

• Karyotype Analysis: Arrangement of homologous chromosomes to identify genetic disorders and individual sex.

• Common Genetic Disorders:

  • Trisomy 21: Down Syndrome with excess chromosome 21, influencing physical traits and health.

Procedure 14.1: Chromosomal Disorders Analysis

• Overview of four sex-linked disorders:

  • Turner’s Syndrome, Poly X Syndrome, Klinefelter’s Syndrome, Jacob’s Syndrome.

Lab 16: Biotechnology Overview

• Biotechnology Application: Use of biological processes for health improvements and environmental solutions.

• Gel Electrophoresis:

  • Separates biomolecules by size and charge, revealing molecular characteristics.

• DNA Extraction: Steps for isolating DNA from cells, highlighting roles of each component in the process.

Lab 18: Evidence of Evolution

• Evolution: Genetic changes over time within a population.

• Comparative Anatomy: Clinical methods for analyzing structural similarities and differences among species.

• Mutations: Source of genetic variation; highlight importance in natural selection and genetic drift.

Natural Selection and Hardy-Weinberg Principle:

• Hardy-Weinberg Law: States allele frequencies should remain constant barring evolutionary influences.

• Equations Used:

  • $p^2 + 2pq + q^2 = 1$

  • Where $p$ = frequency of dominant allele, $q$ = frequency of recessive allele.