D3.2: Inheritance

Guiding Questions

• What patterns of inheritance exist in plants and animals?
• What is the molecular basis of inheritance patterns?

Linking Questions

• Principles of effective sampling in biological research.
• Biological processes involving doubling and halving.

Key Concepts

D3.2.1 - Production of Haploid Gametes

• Definitions:
  • Gamete: A haploid cell that fuses with another during fertilization.
  • Zygote: A diploid cell resulting from the fusion of two haploid gametes.
  • Diploid: A cell with two copies of each autosomal gene.
  • Haploid: A cell with one set of chromosomes.

D3.2.2 - Genetic Crosses in Flowering Plants

• Definitions of P, F1, and F2 generations.
• Experimentally performing genetic crosses via:
  • Cross pollination
  • Self-fertilization
• Application: Determining possible alleles in gametes based on parent genotypes.
• Constructing Punnett grids for single-gene crosses.

D3.2.3 - Genotype

• Gene vs. Allele:
  • Gene: A unit of heredity.
  • Allele: Different forms of a gene.
• Homozygous vs. Heterozygous:
  • Homozygous: Two identical alleles.
  • Heterozygous: Two different alleles.

D3.2.4 - Phenotype

• Genotype vs. Phenotype:
  • Genotype: Genetic makeup.
  • Phenotype: Observable traits.
• Examples of phenotypes caused by:
  • Genotype only
  • Environment only
  • Interaction of genotype and environment

D3.2.5 - Dominant and Recessive Alleles

• Definitions:
  • Dominant Allele: Masks the effect of a recessive allele.
  • Recessive Allele: Expressed only when two copies are present.

D3.2.6 - Phenotypic Plasticity

• Definition: Ability of an organism to change its phenotype in response to environmental conditions.
• Example provided.

D3.2.7 - Phenylketonuria (PKU)

• Carrier: An individual who carries one recessive allele for a genetic disorder.
• Genetic diseases appear unexpectedly.
• PKU:
  • Genetic cause
  • Consequences if untreated
  • Treatment methods

D3.2.8 - Single-Nucleotide Polymorphisms

• New alleles result from mutations.
• Definitions:
  • Single-Nucleotide Polymorphism: Variation at a single position in a DNA sequence among individuals.
  • Gene Pool: Total genetic diversity found within a population or species.
• Mechanism for preventing self-pollination in apple gene pool via multiple alleles.

D3.2.9 - ABO Blood Groups

• Example of complete dominance and codominance.
• Differences in glycoproteins for various blood types.

D3.2.10 - Incomplete Dominance and Codominance

• Definitions:
  • Codominant Alleles: Both alleles are expressed equally.
  • Incomplete Dominance: Blending of traits.
• Examples of codominance and incomplete dominance.

D3.2.11 - Sex Determination in Humans

• Structure and function of sex chromosomes.
• SRY gene’s role in embryonic gonad development.

D3.2.12 - Hemophilia

• Sex Linkage: Genes located on sex chromosomes.
• Inheritance pattern and effects of hemophilia.

D3.2.13 - Pedigree Charts

• Conventions for constructing pedigree charts.
• Deducing inheritance patterns.

D3.2.14 - Continuous Variation

• Continuous vs. Discrete Variation:
  • Continuous: Range of small differences.
  • Discrete: Distinct categories.
• Normal distribution often results from polygenic inheritance.
• Examples of environmental factors affecting phenotypes.

D3.2.15 - Data Representation

• Box-and-Whisker Plots for continuous data.
• Quantitative vs. Qualitative data.
• Identifying outliers.

AHLD3.2.16 - Segregation and Independent Assortment

• Allele segregation during meiosis.
• Independent Assortment: Random orientation of chromosomes.

AHLD3.2.17 - Dihybrid Crosses

• Construction of Punnett squares for dihybrid crosses.

AHLD3.2.18 - Loci of Human Genes

• Gene Locus: Specific location of a gene on a chromosome.

AHLD3.2.19 - Autosomal Gene Linkage

• Characteristics of linked genes and their behavior during meiosis.

AHLD3.2.20 - Recombinants

• Definition and formation through independent assortment and crossing over.

AHLD3.2.21 - Chi-Squared Test

• Calculating and interpreting chi-square values for genetic crosses.

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