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3. Types of Gene Mutations
| Type of Mutation | Definition | Example | |----------------------|------------------------------------|--------------------------------------------------| | Substitution | A single nucleotide is replaced by another nucleotide. | If the sequence is ACGT and it changes to AGGT, the G is substituted for T. | | Insertion | An extra nucleotide is added into the sequence. | If the sequence is ACGT and an A is inserted, it becomes AACGT. | | Deletion | A nucleotide is removed from the sequence. | If the sequence is ACGT and the G is deleted, it becomes ACT. |
4. Types of Chromosomal Mutations
| Type of Mutation | Definition | Example | |--------------------------|----------------------------------------------------------|----------------------------------------------| | Deletion | A segment of the chromosome is lost. | Cri du Chat syndrome - deletion of part of chromosome 5. | | Duplication | A segment of the chromosome is duplicated. | Charcot-Marie-Tooth disease - duplication of the PMP-22 gene on chromosome 17. | | Inversion | A segment of the chromosome is reversed. | Hemophilia A - inversion of part of the factor VIII gene. | | Translocation | Segments from non-homologous chromosomes are exchanged. | Chronic myelogenous leukemia - translocation between chromosomes 9 and 22. |
5. What is Genetic Engineering? Give an Example
Genetic engineering is the direct manipulation of an organism's genes using biotechnology. For example, genetically modified organisms (GMOs) like Bt corn are engineered to express a bacterium's gene that produces a toxin to fend off insect pests.
6. What is Selective Breeding? Give an Example
Selective breeding is the process of breeding plants and animals for particular genetic traits. An example is the breeding of dogs for specific traits such as size, temperament, or coat color, such as breeding Labrador Retrievers for their friendly nature.
7. What is Gene Splicing? When is it Used?
Gene splicing involves inserting, deleting, or altering segments of DNA within a genome. It is often used in genetic engineering to create recombinant DNA, which can be used to produce insulin or other proteins for medical use.
8. What is Gel Electrophoresis?
Gel electrophoresis is a laboratory technique used to separate DNA, RNA, or proteins according to their size and charge. It utilizes an electric field to move the charged molecules through a gel matrix, allowing researchers to analyze the composition of genetic material.
9. What is a DNA Fingerprint?
A DNA fingerprint (or DNA profiling) is a technique used to identify individuals based on unique patterns in their DNA. It analyzes specific regions of DNA that vary greatly between people, allowing for identification in forensic science or paternity testing.
Unit 6: Genetics
1. Mendel's Laws
- Law of Segregation: Each organism carries two alleles for each trait, and these alleles segregate (separate) during gamete formation, so each gamete carries only one allele for each trait.
- Law of Independent Assortment: Alleles for different traits are distributed to gametes independently of one another.
2. Difference Between Homozygous and Heterozygous
- Homozygous: Organism has two identical alleles for a trait (e.g., BB or bb).
- Heterozygous: Organism has two different alleles for a trait (e.g., Bb).
3. Difference Between Dominant and Recessive
- Dominant Allele: An allele that expresses its phenotype even when heterozygous (e.g., B in Bb will express brown).
- Recessive Allele: An allele that expresses its phenotype only when homozygous (e.g., b in bb will express black).
4. Incomplete Dominance and Codominance
- Incomplete Dominance: Neither allele is completely dominant, resulting in a mix of traits (e.g., pink flowers from red and white parents).
- Codominance: Both alleles are fully expressed in the phenotype (e.g., AB blood type from A and B alleles).
5. Phenotypes and Genotypes of Blood Types
- Type A: Genotype (IA IA or IA i); Phenotype (A antigens).
- Type B: Genotype (IB IB or IB i); Phenotype (B antigens).
- Type AB: Genotype (IA IB); Phenotype (A and B antigens).
- Type O: Genotype (ii); Phenotype (no antigens).
6. Genotypic Ratios from Brown Bear (Bb) and Black Bear (bb)
The cross of Bb (brown) with bb (black) would produce the following genotypes:
- Bb (brown): 50%
- bb (black): 50%
Thus, the genotypic ratio would be:
- Bb : bb = 1 : 1
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