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Learning objectives

  • Explain the key points of cell theory and the individual contributions of Hooke, Schleiden, Schwann, Remak, and Virchow
  • Explain the key points of endosymbiotic theory and cite the evidence that supports this concept
  • Explain the contributions of Semmelweis, Snow, Pasteur, Lister, and Koch to the development of germ theory

While some scientists were arguing over the theory of spontaneous generation, other scientists were making discoveries leading to a better understanding of what we now call the cell theory . Modern cell theory has two basic tenets:

  • All cells only come from other cells (the principle of biogenesis).
  • Cells are the fundamental units of organisms.

Today, these tenets are fundamental to our understanding of life on earth. However, modern cell theory grew out of the collective work of many scientists.

The origins of cell theory

The English scientist Robert Hooke first used the term “cells” in 1665 to describe the small chambers within cork that he observed under a microscope of his own design. To Hooke, thin sections of cork resembled “Honey-comb,” or “small Boxes or Bladders of Air.” He noted that each “Cavern, Bubble, or Cell” was distinct from the others ( [link] ). At the time, Hooke was not aware that the cork cells were long dead and, therefore, lacked the internal structures found within living cells.

A drawing make by Hooke that shows many small rectangles in rows making up larger structures.
Robert Hooke (1635–1703) was the first to describe cells based upon his microscopic observations of cork. This illustration was published in his work Micrographia .

Despite Hooke’s early description of cells, their significance as the fundamental unit of life was not yet recognized. Nearly 200 years later, in 1838, Matthias Schleiden (1804–1881), a German botanist who made extensive microscopic observations of plant tissues, described them as being composed of cells. Visualizing plant cells was relatively easy because plant cells are clearly separated by their thick cell walls. Schleiden believed that cells formed through crystallization, rather than cell division.

Theodor Schwann (1810–1882), a noted German physiologist, made similar microscopic observations of animal tissue. In 1839, after a conversation with Schleiden, Schwann realized that similarities existed between plant and animal tissues. This laid the foundation for the idea that cells are the fundamental components of plants and animals.

In the 1850s, two Polish scientists living in Germany pushed this idea further, culminating in what we recognize today as the modern cell theory. In 1852, Robert Remak (1815–1865), a prominent neurologist and embryologist, published convincing evidence that cells are derived from other cells as a result of cell division. However, this idea was questioned by many in the scientific community. Three years later, Rudolf Virchow (1821–1902), a well-respected pathologist, published an editorial essay entitled “Cellular Pathology,” which popularized the concept of cell theory using the Latin phrase omnis cellula a cellula (“all cells arise from cells”), which is essentially the second tenet of modern cell theory. M. Schultz. “Rudolph Virchow.” Emerging Infectious Diseases 14 no. 9 (2008):1480–1481. Given the similarity of Virchow’s work to Remak’s, there is some controversy as to which scientist should receive credit for articulating cell theory. See the following Eye on Ethics feature for more about this controversy.

Questions & Answers

i wante to study medicine in university so how i should prepare my self
Lissa Reply
microorganism functions
NUHU Reply
how does the helicobacteri pylori affect the stomach walls?
Erick Reply
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Allan
Hlo
SUMIT
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Umar
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Umar
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Umar
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Ayan
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vijay Reply
microbiology is the scientific study of microorganisms .microorganisms are those organisms that are too small to see with the naked eye ex-bacteria fungi
Yashkin
a branch of biological science concerned with organisms that can not be observed with a naked eye
Mooya
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lord
polymorpho nuclear leukocyte, known as granulocyte are divide into three,1-polymorpho eosinophil 2-polymorpho basophil 3-polymorpho neutrophil
Musa
microbiology is scientific study of microorganism which can nt be seen by naked eye,for example bacteria,viruses, protozoa ad fungi.
Emma
microbiology is the scientific study of microorganisms
Atia
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blood collection and urinarysis
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Lizzy
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Lizzy
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Aurelia Reply
Hydrogen
Tob
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Aurelia
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Aurelia
hologen
Usman
differences between acid fast and non acid fast bacilli
ANTHONY Reply
acid fast have cell wall that holds to carbol fuschin stain while non acid fast doesn't have. it readily releases out the primary stain the carbol fuschin.
LAFIA
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eklectc
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kennedy
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Olivia
for sure, this question is not related to the topic.
LAFIA
can someone explain the process of glycolysis and the electron transport chain? I'm so freakin lost. it loses carbons, gains hydroxyls, gains, loses Hydrogens....ugh it's like a foreign language to me! or direct me to a youTube video or something that will make this seem easier to concept?
eklectc
it's a loaded question, sorry!
eklectc
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Mcbeth Reply
DNA is genetic material because it contains chromosome contains the traits which includes characters and behavioral characteristics
chima
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Tanaka
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Eddy
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Muhammed Reply
good hygiene
Dhaqan
way of preventing disease causing germs
henry
maintenance of sterilization
Pooja
h
Faustina
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أ‌) Host factor ب) pathogen ج) environment
Widad
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Kofi
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kalai
The epidemiologic triangle is made up of three parts: agent, host and environment
Princess
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Usman
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penicillium notatum
Pooja
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penicillium fungi
Pooja
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Usman
Why can we see ourselves in a mirror?
Usman
mention 5 characteristics of prokaryotic cell and also 5 characteristics of euryotic cell
Grace Reply
PROKARYOTES _ does not have nucleus _does not have membrane bound organels like eukaryotes -does not have endoplasmic reticulum _does not have a mitchochondrion _it have plasmid instead of chromosome EUKARYOTE S _have true nucleus _have all membrane bound organels _have mitochondria have
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continuation _have endoplasmic reticulum _have chromosomes does not have plasmid
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antigenisity define
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explanation of spores
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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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