Genetics & Molecular Biology
Mendelian genetics, DNA structure, replication, gene expression
Key Concepts
- Mendel's 1st law: Law of Segregation — alleles separate during gamete formation
- Mendel's 2nd law: Law of Independent Assortment — genes on different chromosomes assort independently
- Dominant allele masks recessive in heterozygote
- Codominance: both alleles expressed (e.g. ABO blood group type AB)
- Sex-linked traits: carried on X chromosome; males (XY) are more often affected
Important Formulae
| Hardy-Weinberg equation | p² + 2pq + q² = 1; p + q = 1 |
| Monohybrid cross (Aa × Aa) | Phenotype ratio 3:1; genotype ratio 1:2:1 |
| Dihybrid cross (AaBb × AaBb) | Phenotype ratio 9:3:3:1 |
Quick Tips
- Haemophilia and colour-blindness are X-linked recessive — more common in males.
- Chromosomal disorders: Down's (trisomy 21), Turner's (45, X0), Klinefelter's (47, XXY).
- Crossing over in prophase I of meiosis produces genetic recombination.
Sample Practice Questions
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In a monohybrid cross Aa × Aa, the phenotypic ratio in F2 is:
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Answer: 3:1
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Sickle cell anaemia is caused by mutation in which gene?
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Answer: Beta-globin gene (haemoglobin)
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Mendel's law of segregation states that alleles:
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Answer: Separate during gamete formation
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Transcription produces:
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Answer: mRNA from DNA template
Practice Questions
Practice 20 randomly selected NEET questions on Genetics & Molecular Biology. Answers are revealed after each question.
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What are the key concepts in Genetics & Molecular Biology for NEET?
Mendel's 1st law: Law of Segregation — alleles separate during gamete formation; Mendel's 2nd law: Law of Independent Assortment — genes on different chromosomes assort independently; Dominant allele masks recessive in heterozygote; Codominance: both alleles expressed (e.g. ABO blood group type AB); Sex-linked traits: carried on X chromosome; males (XY) are more often affected.
Which formulae are important for Genetics & Molecular Biology in NEET?
Hardy-Weinberg equation: p² + 2pq + q² = 1; p + q = 1; Monohybrid cross (Aa × Aa): Phenotype ratio 3:1; genotype ratio 1:2:1; Dihybrid cross (AaBb × AaBb): Phenotype ratio 9:3:3:1.
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