Most eukaryotes reproduce sexually, which involves the fusion of two gametes.
Gametes are created by meiosis.
The process of fusing gametes is called fertilization.
Fusion of haploid gametes results in a diploid offspring.
Genetic variation is increased in a population through sexual reproduction, leading to genetically unique individuals.
Genetic Variation
Offspring resemble their parents despite sexual reproduction creating unique individuals.
Gregor Mendel (1865) contributed to the understanding of heredity by working out the rules of inheritance through experiments on garden peas.
Gregor Mendel
Mendel was a monk residing in an Austrian monastery dedicated to scientific teaching and research.
He studied natural sciences, physics, and mathematics at the University of Vienna.
Mendel formed an agricultural society that emphasized research to improve breeding programs.
Mendel's Contribution to Genetics
Crucial contribution: systematic, mathematical analysis of quantitative data, contrasting with previous qualitative biases.
Utilized large sample sizes, counting thousands of offspring across numerous experiments.
First to approach biological experiments with a rigorous methodology, which was vital for his discoveries.
Focus of Mendel's Experiments
Aimed to address fundamental questions regarding heredity: What are the basic patterns of heredity?
Definitions:
Genetics: Study of gene sequences, a component of heredity.
Heredity: Transmission of traits from parents to offspring.
Trait: Observable characteristics of an organism (e.g., size, color, shape).
Mendel's Experiments
Explored two major hypotheses of heredity prevalent during his time:
Blending Inheritance: Suggests that genetic material from parents blends together; example: crossing a red flower with a white flower results in a pink flower.
Inheritance of Acquired Characteristics: Proposed by Jean-Baptiste Lamarck in 1809; suggests that traits present in parents are modified through use and passed on to offspring in their modified form (e.g., giraffes stretching their necks leads to longer necks in descendants).
Heredity Hypotheses - Mendel's Discovery
Neither of the prevailing hypotheses had experimental backing but were accepted by the scientific community.
Mendel discovered the fundamental principles of heredity by engaging in careful breeding with garden peas, choosing an appropriate model organism for his experiments.
A model organism typically has qualities such as being small, short-lived, inexpensive to care for, producing many offspring in a short period, and being amenable to experimental manipulation.