Cells Flashcards
What are three examples of spontaneous generation?
Maggot from meat
Lice from dirt or sweat
Worms from mud
What is spontaneous generation?
The idea that living creatures spontaneously originated from nonliving matter
What are the three components of the cell theory?
The cell is the basic unit of organization for all organisms
All living things are made up of cells
All cells come from pre-existing cells
What contribution did Anton van Leeuwenhoek make to the cell theory?
Made his own microscope
● Viewed bacteria on his own teeth
● Called these single-celled organisms “animalcules”
What contribution Robert Hooke make to the cell theory?
Looked at a slice of cork under a microscope
● Felt that the microscopic units making up the structure of the cork
looked like little rooms
● In Latin, the word “cella” means small room
● Coined the term cells to refer such units
What contribution did Matthias Jakob Schleiden make to the cell theory?
Botanist studying plants
● Observed that all plants are made up of cells
What contribution did Theodor Schwann make to the cell theory?
Studied animal tissue
Observed that all animals are made up of cells
What contribution did Rudolf Virchow make to the cell theory?
Spontaneous generation had been disproved by Louis Pasteur
● Rudolf proposed the idea that all cells come from other cells
What was Francesco Redi’s experiment?
● Francesco Redi’s experiment
● He placed meat in 3 jars
○ Jar 1 = open
○ Jar 2 = sealed completely
○ Jar 3 = sealed with
gauze (has small openings on top)
● Exp Results:
○ Maggots found on the meat in the open jar (#1)
○ No maggots found in the sealed jar (#2)
○ Maggots found on top of the gauze in jar 3, but not on the meat
This does not support the spontaneous generation theory.
What experiment did John Needham test?
John Needham did his experiment first
○ Set up 2 flasks w/ broth, one heated, one unheated.
○ The flasks were left open for a few days BEFORE sealing
○ Both flasks had bacteria.
○ ERROR: Leaving the flasks open allowed bacteria to enter during
this time!
What contribution did Lazzaro Spallanzani to the cell theory?
Lazzaro Spallanzani did his experiment after Needham ○ Set up 2 flasks w/ broth ○ Flask 1 = heated and left open ○ Flask 2 = heated and sealing, w/ air removed ○ Only the open flask had bacteria.
What contribution did Louis Pasteur make to the cell theory?
Louis Pasteur’s experiment
○ Used swan neck flask containing
broth
○ Heated the broth
○ Air could pass through to the broth,
but bacteria could not
● After a few days, no bacteria was found
inside the flask.
● After the neck of the flask was broken off
and left open, bacteria was detected inside the broth.
What was the purpose of designing and using a flask with a swan-neck in Louis Pasteur’s experiment?
The swan neck allowed air to flow through to the broth (critique of Spallanzani’s experiment), but trapped bacteria in the “neck”, so that it could not access the broth.
What was the purpose of boiling the broth?
Boiling the broth kills the bacteria that was already present inside the broth.
Eliminating this bacteria allows scientists to tell whether there is new growth.
In an experiment, a scientist filled two open flasks, as shown in the figure below, with broth and boiled the broth until it became clear.
Clear broth indicates that there is NO bacteria present, while cloudy broth indicates that bacteria IS present.
He then left the flasks open for several days. Which choice describes the result that would have occurred in this set up?
a. The broth in both Flasks A and Flask B remained clear.
b. The broth in both Flask A and Flask B became cloudy.
c. The broth in Flask A remained clear, and the broth in Flask B became cloudy.
d. The broth in Flask A became cloudy, and the broth in Flask B remained clear.
