General biologyLesson 1 of 2 in the course The Cell

Historical Foundations of Cell Theory, Endosymbiosis, and Germ Theory

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Cell theory explains what cells mean to the structure and continuity of life. This lesson follows the observations and ideas of scientists whose work established its central principles.

In 1665, English scientist Robert Hooke examined a thin slice of cork through a microscope he had designed. He saw a pattern of small chambers and used the word cells to describe them. Cork consists of plant tissue whose cells are dead, so Hooke observed empty cell walls rather than the internal structures of living cells. His description named the structures, but their importance as the basic units of life was not yet understood.

All flashcards

What are the two basic tenets of modern cell theory?
Cells are the fundamental units of organisms, and all cells arise from other cells.
What did Schleiden contribute to cell theory?
He concluded that plant tissues are composed of cells, although he incorrectly proposed that cells formed by crystallization.
How did Remak and Virchow contribute to the principle that cells come from cells?
Remak published evidence for cell formation by division in 1852; Virchow later popularized the principle in 1855 without crediting him.
What did Lynn Margulis contribute to endosymbiotic theory?
In 1967, she synthesized evidence supporting the idea that mitochondria and chloroplasts originated from prokaryotic organisms.
Why do mitochondria and chloroplasts have reduced genomes?
Many genes from their bacterial ancestors were transferred to the host cell's nucleus.

Quiz questions

  1. What did Pasteur's swan-neck flask experiments demonstrate?Answer: Airborne microbes could contaminate a suitable liquid when they reached it.
  2. Which observation supports a bacterial origin for mitochondria and chloroplasts?Answer: Their DNA resembles bacterial DNA in sequence and chromosome structure.
  3. How did Joseph Lister apply ideas about microbial contamination to surgery?Answer: He used cleanliness and carbolic acid to reduce postsurgical infections.
  4. What route of cholera transmission did John Snow identify?Answer: Drinking water contaminated by sewage.
  5. What were Koch's postulates designed to test?Answer: Whether a particular microorganism causes a particular disease.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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