Lesson 1: Molecular Biology - Questions and Answers
1. Define Molecular Biology:
It is a branch of biology that studies the structure and function of genes at a molecular level, focusing on the interactions between DNA, RNA, and proteins within the cell.
2. Define Transmission Genetics:
It is the study of the inheritance of traits from parents to offspring, without focusing on the chemical structure of genes.
3. Define Gene and Allele:
Gene: The unit of heredity that carries information and is located on chromosomes.
Allele: An alternative form of a gene, which can be dominant or recessive.
Allele: An alternative form of a gene, which can be dominant or recessive.
4. Define Genotype and Phenotype:
Genotype: The genetic composition of an organism.
Phenotype: The observable characteristics resulting from the genotype.
Phenotype: The observable characteristics resulting from the genotype.
5. Define Genetic Recombination:
It is a process that occurs during meiosis, where parts of DNA are exchanged between chromosomes to produce genetic diversity.
6. Mention the relationship between Molecular Biology and other sciences:
It is related to genetics and biochemistry, and utilizes bioinformatics to understand cellular interactions.
7. State Mendel's basic laws of inheritance:
- Law of Segregation
- Law of Independent Assortment
- Presence of dominant and recessive alleles
- Law of Independent Assortment
- Presence of dominant and recessive alleles
8. State the characteristics of diploid and haploid cells:
- Diploid: Contains a pair of each chromosome.
- Haploid: Contains only one copy of each chromosome.
- Haploid: Contains only one copy of each chromosome.
9. List the steps of genetic recombination:
- Pairing of homologous chromosomes
- Crossing over occurs
- Exchange of genetic segments
- Production of new genetic combinations
- Crossing over occurs
- Exchange of genetic segments
- Production of new genetic combinations
10. What is the physical evidence of recombination?
It has been observed using microscopes in the chromosomes of maize and fruit flies, where distinct exchanges in genetic material have been noted.
11. Explain Mendel's laws with an example:
Through pea plant hybridization, Mendel concluded that traits are inherited via alleles, some dominant and some recessive. For example, if one parent carries the dominant allele for height, height will appear in the first generation.
12. Explain the chromosomal theory of inheritance:
It states that genes are located on chromosomes and are inherited from parents to offspring through cell division. This was proven through experiments by Thomas Morgan.
13. Explain the difference between hybrid and homozygous:
A hybrid carries two different alleles (Aa), while homozygous carries two identical alleles (AA or aa).
14. Explain the principle of genetic linkage:
Genes located on the same chromosome are often inherited together, but crossing over can separate them, so linkage is not absolute.
15. How are genetic crosses used to understand traits?
Individuals with known genotypes are crossed, and the traits in the offspring are observed to determine the pattern of inheritance (dominant/recessive) and allele patterns.
16. Compare between autosomes and sex chromosomes:
Autosomes: 22 pairs, determine general traits.
Sex chromosomes: One pair, determine sex (XX for female, XY for male).
Sex chromosomes: One pair, determine sex (XX for female, XY for male).