Genetics and Cell Division

Genetics and Cell Division

1. DNA

  • Definition: Molecule carrying genetic instructions necessary for the growth, development, functioning, and reproduction of all living organisms.

2. Chromosome

  • Definition: DNA-containing structure that carries genetic material from one generation to another.

  • Function: Ensures that DNA is accurately copied and distributed in the vast majority of cell divisions.

3. Cell Cycle

  • Definition: Series of events leading to cell division.

  • Stages: Involves several phases that a cell goes through to divide and reproduce.

4. Interphase

  • Definition: Phase of the cell cycle where cell growth and DNA replication occur.

  • Duration: It encompasses three parts: G1 (first gap), S (synthesis), and G2 (second gap).

5. Mitosis

  • Definition: Process of cell division in which the nucleus divides into nuclei containing the same number of chromosomes.

  • Importance: Essential for growth, development, and repair in multicellular organisms.

  • Phases: Includes prophase, metaphase, anaphase, and telophase.

6. Cytokinesis

  • Definition: Division of the cytoplasm to form two separate daughter cells.

  • Occurrence: Often occurs immediately after mitosis, ensuring two distinct cells result.

7. Homologous Chromosomes

  • Definition: Pair of chromosomes that have the same genes at the same loci, but possibly different alleles.

  • Role: Important in sexual reproduction and genetic variation.

8. Meiosis

  • Definition: Type of cell division that produces reproductive cells in sexually reproducing organisms.

  • Outcome: Results in four non-identical daughter cells with half the original number of chromosomes (haploid).

9. Asexual Reproduction

  • Definition: The production of genetically identical offspring from a single parent.

  • Mechanism: Includes processes such as binary fission, budding, and vegetative propagation.

10. Sexual Reproduction

  • Definition: Reproduction that involves the union or fusion of a male gamete and a female gamete.

  • Advantage: Leads to genetic diversity among offspring.

11. Fertilization

  • Definition: The action or process of fertilizing an egg.

  • Mechanism: Involves the fusion of male and female gametes to form a zygote.

12. Heredity

  • Definition: The passing of traits from parents to offspring.

  • Mechanism: Involves transmission of genetic information via genes.

13. Gene

  • Definition: Segments of DNA on a chromosome that code for a specific trait.

  • Significance: Basic unit of heredity.

14. Allele

  • Definition: Variant or different forms of a gene.

  • Role: Determine variations in traits among individuals.

15. Genotype

  • Definition: The specific genetic makeup or set of alleles of an organism.

  • Contrast: Different from phenotype which refers to observable traits.

16. Phenotype

  • Definition: The observable physical traits of an organism.

  • Example: Traits such as height, color, shape etc.

17. Dominant Allele

  • Definition: An allele whose trait is always expressed in the organism when the allele is present.

  • Contrast: Masks the effect of a recessive allele when both are present.

18. Recessive Allele

  • Definition: An allele that is masked by the presence of a dominant allele.

  • Condition: Must be homozygous (two copies) to be expressed in the phenotype.

19. Incomplete Dominance

  • Definition: Occurs when the heterozygous phenotype is a blend of the two alleles.

  • Example: Red and white flowers producing pink flowers.

20. Codominance

  • Definition: Occurs when the heterozygous phenotype shows both alleles distinctly.

  • Example: AB blood type expresses both A and B antigens.

21. Genetic Modification

  • Definition: The process of altering the DNA of an organism.

  • Purpose: To improve desired traits, enhance characteristics or introduce new traits.

22. Genetics

  • Definition: The study of genes, genetic variation, and heredity in living organisms.

  • Application: Provides insights into inheritance patterns and genetic diseases.

23. Law of Independent Assortment

  • Definition: Mendel's Second Law stating that allele pairs separate independently during gamete formation.

  • Implication: Each pair of alleles segregates independently of other pairs, leading to genetic variation.

24. Pedigree

  • Definition: A chart or "family tree" that tracks which members of a family have a particular trait.

  • Purpose: Used to analyze the inheritance patterns of traits across generations.

25. Traits

  • Definition: Specific characteristics or attributes that an organism can pass on to its offspring through its genes.

  • Types: Can include physical features, behaviors, or biochemical properties.

26. Law of Segregation

  • Definition: Mendel's First Law which states that pairs of homologous chromosomes separate during meiosis.

  • Outcome: Each gamete receives only one chromosome from each pair, ensuring genetic diversity.

27. Gamete

  • Definition: A mature haploid male or female germ cell capable of uniting with another of the opposite sex to form a zygote.

  • Importance: Essential in sexual reproduction and genetic variation.

28. Artificial Selection

  • Definition: The practice by which humans select plants or animals for breeding based on desired traits.

  • Application: Important in agriculture for optimizing crop and livestock traits.

29. Natural Selection

  • Definition: The process by which organisms that inherit advantageous traits tend to reproduce more successfully than other organisms.

  • Implication: Key mechanism of evolution, leading to adaptation over generations.

30. Charles Darwin

  • Definition: An English natural scientist known for formulating the theory of evolution by natural selection (1809-1882).

31. Five Points of Natural Selection

  1. Populations have variations - Individual organisms in a population exhibit variations in their traits.

  2. Some variations are favorable - Certain traits may provide an advantage in survival or reproduction.

  3. More offspring produced than survive - Many offspring are born, but not all can survive due to competition and environmental factors.

  4. Individuals that survive will have more favorable traits - These individuals are more likely to pass their advantageous traits to the next generation.

  5. A population will change over time - Over generations, favorable traits become more common in the population, leading to evolution.