biology

Theophilus Painter

Theophilus Painter is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Theophilus Painter rather than just read about it. In short: Theophilus Shickel Painter (August 22, 1889 – October 5, 1969) was an American zoologist best known for his work on the structure and function of chromosomes, especially the sex-determination genes X and Y in humans. He was the first to discover that human sex was determined by an X/Y heteromorphic chromosomal pair mechanism.

Key takeaways

Theophilus Painter belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Theophilus Painter to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Theophilus Painter from memory before moving on to harder problems.

Reference excerpt

Theophilus Shickel Painter (August 22, 1889 – October 5, 1969) was an American zoologist best known for his work on the structure and function of chromosomes, especially the sex-determination genes X and Y in humans. He was the first to discover that human sex was determined by an X/Y heteromorphic chromosomal pair mechanism. He also carried out work in identifying genes in fruit flies (Drosophila). His work exploited the giant polytene chromosomes in the salivary glands of Drosophila and other Dipteran larvae. Painter was elected to the United States National Academy of Sciences in 1938 and the American Philosophical Society in 1939.

Academic administration Painter joined the faculty at the University of Texas in 1916 and, except for military duty during World War I, stayed there his whole career. He was, in succession, associate professor, professor and distinguished professor of zoology. He served as acting president (1944–1946) and president (1946–1952) of the University of Texas and retired from active teaching in 1966.

Racial segregation Painter was president of the University of Texas when Texas resident Heman Marion Sweatt applied for and was denied admission due to his race. Painter spoke out against integration, and voiced his disapproval of Sweatt's admittance. Sweatt v. Painter, 339 U.S.629 (1950), which proved an integral stepping stone in the landmark case Brown v. Board of Education of Topeka, Kansas that held that "separate is inherently unequal" and led to the integration of America's public schools.

Gender research Painter is also known for his early study of human chromosomes. In a paper published in 1923, he first gave the number 24 for the count of human meiotic chromosomes. He had tried to count the tangled mass of chromosomes he could see under a microscope in spermatocytes in slices of testicle and arrived at the figure of 24. Others later repeated his experiment in other ways and agreed upon the number of 24. Popular thinking held that if there were 24 chromosomes in spermatocytes, there must be an equal number contributed by the female and the human chromosome number must be 48, which was undisputed for more than 30 years. Then in 1955, Joe Hin Tjio and Albert Levan, using more advanced techniques, looked at the chromosomes in human somatic cells and found 46 chromosomes and the human chromosome number was finally revised. In 1934 Painter was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences.

See also Argument from authority § Use in science Chromosome § Historical note

References

External links Theophilus Shickel Painter from the Handbook of Texas Online Theophilus Painter—Biographical Memoirs of the National Academy of Sciences

Worked examples

Example 1 — a first encounter with Theophilus Painter

Start with the simplest possible case. Write down what Theophilus Painter claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Theophilus Painter before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Theophilus Painter ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Theophilus Painter

In research: Theophilus Painter appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Theophilus Painter in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Theophilus Painter is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1889 births, 1969 deaths, 20th-century American academics, so understanding it makes those chapters shorter.
In everyday life: Look for Theophilus Painter outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Theophilus Painter in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Theophilus Painter means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Theophilus Painter out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Theophilus Painter in simple terms?

Why does Theophilus Painter matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Theophilus Painter?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Theophilus Painter.