Biology
Form IV
BIO-F4-04
✓ Verified TIE Syllabus
Genetics and Variation
Comprehensive introduction to classical and molecular genetics: DNA and RNA structure, Mendelian laws of inheritance, monohybrid crosses, codominance, sex determination, sex-linked traits, gene mutations, and phenotypic variation.
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🎯 Syllabus Competencies & Learning Objectives
Key Competencies
- Main: 1.0 Demonstrate mastery of the concepts, principles and processes of Biology
- Specific: 1.1 Describe the physiological, anatomical and ecological processes of living organisms
Specific Learning Objectives
- Describe the structure of genetic material: nucleotides, DNA double helix, chromosomes, genes.
- Differentiate between genotype and phenotype, homozygous and heterozygous alleles.
- State and demonstrate Mendel's First Law of Segregation using Punnett squares.
- Explain non-Mendelian inheritance patterns: codominance and incomplete dominance.
- Explain sex determination in humans and sex-linked inheritance (hemophilia, red-green color blindness).
- Differentiate continuous variation from discontinuous variation.
- Explain causes and consequences of gene and chromosomal mutations.
📖 Comprehensive Study Notes Summary
### Genetics and Principles of Inheritance
#### Gregor Mendel's First Law (Law of Segregation)
During gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene.
#### Standard Monohybrid Cross (Complete Dominance)
- Parents: TT x tt (Tall x Short)
- F1 Generation: All Tt (Phenotype: 100% Tall)
- F1 Self-cross: Tt x Tt
- F2 Genotypes: 1 TT : 2 Tt : 1 tt
- F2 Phenotypic Ratio: **3 Tall : 1 Short**
#### Sex-Linked Inheritance
Sex-linked genes reside on the X chromosome without corresponding alleles on the smaller Y chromosome. Examples: Hemophilia (X^h) and Red-green color blindness (X^c).
- Carrier female: X^H X^h
- Affected male: X^h Y (males need only one recessive allele to manifest the disorder).
#### Types of Variation
- **Continuous Variation**: Shows a gradual transition between extremes with normal distribution curve, influenced by multiple genes and environment (e.g. human height, weight, skin color).
- **Discontinuous Variation**: Distinct clear-cut categories with no intermediates, purely genetic (e.g. ABO blood groups, ability to roll tongue, earlobe attachment).
#### Gregor Mendel's First Law (Law of Segregation)
During gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene.
#### Standard Monohybrid Cross (Complete Dominance)
- Parents: TT x tt (Tall x Short)
- F1 Generation: All Tt (Phenotype: 100% Tall)
- F1 Self-cross: Tt x Tt
- F2 Genotypes: 1 TT : 2 Tt : 1 tt
- F2 Phenotypic Ratio: **3 Tall : 1 Short**
#### Sex-Linked Inheritance
Sex-linked genes reside on the X chromosome without corresponding alleles on the smaller Y chromosome. Examples: Hemophilia (X^h) and Red-green color blindness (X^c).
- Carrier female: X^H X^h
- Affected male: X^h Y (males need only one recessive allele to manifest the disorder).
#### Types of Variation
- **Continuous Variation**: Shows a gradual transition between extremes with normal distribution curve, influenced by multiple genes and environment (e.g. human height, weight, skin color).
- **Discontinuous Variation**: Distinct clear-cut categories with no intermediates, purely genetic (e.g. ABO blood groups, ability to roll tongue, earlobe attachment).