GENERAL SCI GENETICS

Father of Genetics

  • Gregor Mendel

Mutations

  • Definition: Permanent change in the DNA sequence that results in a new allele.

    • Involves a change in the order of DNA bases.

    • Results in altered genes, amino acids, and proteins.

Pedigree Charts

  • Example of Two White Sheep Producing a Black Sheep:

    • Both must be heterozygous.

    • Each parent contributes a recessive gene, resulting in a black phenotype.

    • Dominant genes mask recessive genes in parents.

DNA, Chromosomes, Genes, and Alleles Relation

  • Chromosomes: Composed of DNA.

  • Genes: Sections of DNA coding for specific traits.

  • Alleles: Variations of a gene due to differences in DNA base sequences.

Phenotype Ratio Predictions vs Actual Ratio

  • Punnet Squares: Only predict outcomes; real results may vary due to random fertilization.

  • Increasing sample size improves accuracy of predicted ratios.

Homozygous vs Heterozygous

  • Heterozygous: One dominant and one recessive allele.

  • Homozygous: Two identical alleles (either dominant or recessive).

Genetic Variation in Strawberry Plants via Meiosis

  • Sexual Reproduction: Involves variation beneficial for adaptation through natural selection.

  • Meiosis Events: Includes crossing over and independent assortment, leading to genetic variation.

Natural Selection and Heritable Traits

  • Organisms adapt to their environment to enhance survival; favorable traits are passed to offspring.

Pure Breeding and Test Crosses

  • Pure Breeding: Homozygous dominant or recessive organisms produce offspring with consistent traits.

  • Test Cross: Used to determine the genotype of an organism expressing a dominant phenotype by breeding it with a homozygous recessive organism.

Genetic Variation

  • Definition: Differences in traits among individuals of the same species.

  • Types:

    • Heritable: Passed down genetically (e.g., eye color).

    • Non-heritable: Result of the environment (e.g., scars).

  • Discrete Variation: Group fitting (e.g., blood type).

  • Continuous Variation: Spectrum traits (e.g., height).

DNA Structure and Function

  • DNA: Deoxyribonucleic acid; double-helix structure made of nucleotides (A, T, C, G).

  • Functions: Carries genetic code; complementary base pairing enables DNA replication and gene expression.

Importance of Heritable Variation

  • Natural Selection Steps:

    1. Variation among individuals.

    2. Environmental changes affect survival.

    3. Survival of the fittest occurs.

    4. Reproductive success leads to passing on of favorable alleles.