Genetics Quiz: Mendel and His Discoveries

Study Notes

Genetics Overview

Genetics studies heredity and variation among organisms.
Key terms include genetikos (generative) and genesis (beginning).
Heredity refers to traits passed from parent to offspring; variation indicates differences among individuals of a species.

Artificial Selection & Domesticated Animals

Artificial selection involves choosing desirable traits in organisms.
Early domesticated animals include horses, oxen, camels, and dogs.

Notable Horse Breeds

Arabian horses were developed in the Middle East's deserts by nomadic tribes.
Other significant breeds: Polish, Egyptian, Spanish, and Russian horses.

Historical Figures in Genetics

Aristotle believed male semen's "vital heat" influenced offspring traits.
Charles Darwin introduced the theory of evolution via natural selection and authored "On the Origin of Species."
Gregor Mendel, known as the Father of Genetics, studied pea plants and established Laws of Inheritance.

Mendel's Laws

Law of Dominance: dominant traits mask recessive ones.
Law of Segregation: alleles segregate during gamete formation.
Law of Independent Assortment: traits are inherited independently.

Advancements in DNA Research

Friedrich Miescher discovered DNA in 1869 and identified its acidic nature.
William Henry Sutton linked chromosome behavior to gene inheritance, leading to the chromosomal theory of inheritance.
Thomas Hunt Morgan found sex-linked traits in fruit flies and confirmed genetic material location on chromosomes.

Key Experiments and Findings

Frederick Griffith defined "transformation" in bacteria.
Oswald Avery determined DNA functions as the "transforming substance" in 1944.
Hershey & Chase proved DNA is the hereditary material, not proteins, through their phage experiments.

Chargaff's Contributions

Erwin Chargaff discovered nucleotide composition varies between species.
Chargaff’s Rule outlines predictable ratios of nitrogen bases:
- Adenine (A) - 30.9%
- Thymine (T) - 29.4%
- Guanine (G) - 19.9%
- Cytosine (C) - 19.8%

DNA Structure Discoveries

Linus Pauling proposed a triple helix model; he won the Nobel Prize in Chemistry in 1954.
Rosalind Franklin and Maurice Wilkins used X-ray crystallography to reveal DNA's helical structure.
James Watson and Francis Crick constructed the double helix model of DNA, winning the Nobel Prize in 1962.

The Central Dogma

In 1959, Francis Crick articulated the central dogma: DNA → RNA → protein.
This framework explains molecular information flow and mutation understanding.

Genetics Timeline

1860s: Mendel's pea plant experiments establish discrete unit inheritance.
1870s: Friedrich Miescher describes nucleic acids.
1909: Wilhelm Johannsen coins the term ‘gene’.
1910: Thomas Morgan demonstrates genes are located on chromosomes.
1944: Oswald Avery identifies nucleic acids as the transforming principle in bacteria.
1953: Watson and Crick publish the double helix model.
1958: Crick proposes the central dogma of molecular biology.
1977: Discovery of protein-coding genes in segments by Phillip Sharp and Richard Roberts.
2001: Human Genome Project publishes initial results.

Genetic Concepts

Chromosomes: double-stranded DNA molecules packaged with histones, with a constant number for each organism (e.g., humans have 46 chromosomes).
Homologous chromosomes share centromere position, size, and contain identical gene sets at corresponding loci.
Genes are DNA sequences that produce RNA and encode proteins, determining individual traits.
The locus refers to a specific position on a chromosome for a particular gene.

Description

Test your knowledge on the fundamentals of genetics with this quiz focused on key figures and concepts. Explore Mendel's principles, learn about artificial selection, and match scientists to their contributions. Ideal for students of genetics and biology enthusiasts.