History of Germ Theory and Fertilization

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Questions and Answers

What theory did Weismann propose regarding heredity?

Weismann proposed the GERM THEORY, stating that heredity factors are transferred through the continuity of germplasm in sperm and egg, not through somatic cells.

What significant discovery regarding fertilization was made by O. Hertwig and H. Fol?

O. Hertwig and H. Fol discovered fertilization in animals.

How did Strassburger contribute to the understanding of heredity?

Strassburger discovered fertilization in plants and helped substantiate the idea that the cell nucleus is the bearer of hereditary information.

What did Gregor Mendel discover in 1865?

Gregor Mendel discovered the Fundamental Law of Heredity through his experiments with pea plants. Signup and view all the answers

What was the significance of Theodor Boveri's suggestion in 1890?

Theodor Boveri suggested that chromosomes play a crucial role in inheritance. Signup and view all the answers

What did Sutton and Boveri independently propose about egg and sperm cells?

Sutton and Boveri proposed that each egg or sperm cell contains only one of each chromosome pair. Signup and view all the answers

What did Edmund Beecher Wilson and Nettie Stevens discover about sex determination?

Wilson and Stevens independently proposed that certain chromosomes determine sex, with one Y chromosome indicating maleness and two X chromosomes indicating femaleness. Signup and view all the answers

What was the outcome of Mendel's work during the years 1900 to 1901?

Mendel's work was rediscovered by Hugo De Vries, Erich von Tschermack, and Carl Correns. Signup and view all the answers

In what year did Bateson first use the term 'genetics'?

1906 Signup and view all the answers

What significant contributions to genetics were made by Thomas Hunt Morgan in 1910?

He proved that genes are carried on chromosomes and that some characteristics are associated with sex chromosomes. Signup and view all the answers

Who discovered that DNA is the hereditary material and in what year?

Oswald Avery, Colin Macleod, and Maclyn McCarty in 1944. Signup and view all the answers

What groundbreaking structure of DNA was proposed by James Watson and Francis Crick in 1953?

The double-stranded helix structure. Signup and view all the answers

What was one of the key findings of Erwin Chargaff in 1949 regarding DNA composition?

He found that the amounts of adenine and thymine are roughly equal, as are guanine and cytosine. Signup and view all the answers

What was the significance of the year 2003 in genetics?

The Human Genome Project was successfully completed. Signup and view all the answers

Who sequenced the first human gene linked to a genetic disease, and what was the gene for?

Francis Collins and Lap-chee Tsui sequenced the cystic fibrosis gene in 1989. Signup and view all the answers

What important technique for DNA amplification was discovered by Kary Mullis, and in what year?

The Polymerase Chain Reaction (PCR) in 1983. Signup and view all the answers

Study Notes

Historical Milestones in Genetics

1883: Germ cells observed by Van Beneden, Fleming, Strassburger, and Boveri; supported Weismann's continuity of germ plasm theory.
1883: Weismann proposed GERM THEORY, emphasizing inheritance through germplasm (sperm & egg) rather than somatic cells.
1879: O. Hertwig and H. Fol noted the discovery of fertilization processes in animals.
N/A: Strassburger discovered fertilization in plants, suggesting that the cell nucleus carries hereditary information.
N/A: Roux theorized that chromatin within chromosomes has a linear organization.
N/A: Weismann stated that hereditary units are organized orderly along chromosomes.
1865: Gregor Mendel introduced the Fundamental Law of Heredity, marking a significant advancement before the cytological basis of sex cells was fully understood.
1865/1866: Mendel published his research on pea plant inheritance.
1890: Theodor Boveri proposed that chromosomes play a crucial role in inheritance.
1900: Walter Sutton observed chromosomes in grasshopper cells, enhancing chromosomal theory.
1900/1901: Mendel's work was rediscovered by De Vries, von Tschermack, and Correns.
1902: Archibald Garrod discovered that some diseases have an inherited nature.
1903: Sutton and Boveri suggested that gametes contain one of each chromosome pair.
1905: Wilson and Stevens proposed certain chromosomes determine sex; the Y chromosome indicates male, while two X chromosomes indicate female.
1906: Bateson coined the term "genetics" to describe heredity and variation.
1909: Wilhelm Johannsen defined 'gene', 'genotype', and 'phenotype' to categorize heredity and traits.
1910: Thomas Hunt Morgan demonstrated that genes reside on chromosomes and identified sex-linked traits.
1911/1913: Alfred Henry Sturtevant created the first gene map of the fruit fly's sex chromosome.
1912: Bragg and his son discovered that X-rays can investigate molecular structures in crystals.
1926: Morgan published the Theory of the Gene, advancing genetic understanding.
1928: Griffith discovered transformation, a fundamental process in bacteria.
1944: Avery, Macleod, and McCarty established DNA as the genetic material using bacterial experiments.
1949: Chargaff determined equal amounts of adenine-thymine and guanine-cytosine in DNA.
1953: Watson and Crick proposed the double-stranded helix structure of DNA.
1963-1966: Nirenberg and Matthaei deciphered the genetic code, revealing how DNA encodes protein sequences.
1977: Sanger, Gilbert, and Maxam independently sequenced viral DNA for the first time.
1983: Kary Mullis developed the Polymerase Chain Reaction (PCR), allowing amplification of DNA segments.
1987: Cann, Stoneking, and Wilson analyzed mitochondrial DNA, proposing a common human ancestor from 200,000 years ago.
1989: Collins and Tsui sequenced the first human gene linked to cystic fibrosis.
1990: Launch of the Human Genome Project aimed at mapping the entire human genome.
1993: Cystic fibrosis became the first genetic disease treated with gene therapy.
1995: The complete genome of Haemophilus influenzae was sequenced, marking a breakthrough in genomics.
2000: First draft sequences of the human genome published by the Human Genome Project and Celera Genomics.
2003: Completion of the Human Genome Project was announced on April 14, confirming the full mapping of human DNA.

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Description

This quiz explores key discoveries in germ theory and fertilization, highlighting contributions from scientists like Weismann, Strassburger, and Hertwig. Delve into the milestones that shaped our understanding of heredity and the continuity of germ plasm in both plants and animals.