Chapter 2. Basic components of living systems Flashcards
By who and when was the first cell observed
In 1665 by Robert Hooke using a light microscope
By who and when were the first living cells observed
1674-1863 by Anton van Leeuwenhoek
By who and when was there evidence for the origin of new plant cells
1832 by Barthélemy Dumortier
By who and when was the nucleus first observed
1833 by Robert brown
By who and when was the birth of a universal cell theory theory
1837-1838 by Matthias Schielden
What was the first universal cell theory
It was proposed that all plants and animals are composed of cells and cell products
By who and when was the first evidence for the origin of new animal cells
1844 (1855) by Robert Remak
By who and when was spontaneous generation disproved
1860 by Louis Pasteur
How does a light microscope work (briefly outline)
It has two lenses, the eyepiece lens and the objective lens. The objective lens produces a magnified image which is magnified again.
What is the benefit of using two lenses compared to one in a simple light microscope
The objective/eyepiece lens configuration allows for much higher magnification and reduced chromatic aberration
What is chromatic aberration
The failure of a lens to focus all colours to the same point
What is the purpose of staining
To increase contrast between different parts of a cell
What is magnification
How many times larger an image appears compared to its actual size
What is resolution
The ability to see individual objects as separate entities
What is the equation for magnification
magnification = image size / actual size
What is the equation for actual size of an object
Actual size of an object = size of image / magnification
What is the equation for size of the image
Size of image = magnification x actual size of object
What is the benefit to using a electron microscope over a light microscope
Higher magnification
What is the limiting factor to a light microscope
Resolution
Outline how an electron microscope works
A beam of electrons with less than 1nm wavelength is used to illuminate the specimen. This means more detail of the cell can be seen because electrons have a much smaller wavelength than light waves.
Up to what magnification can electron microscopes produce
x500 000
What are the two types of electron microscope
Transmission electron microscopes (TEM) and Scanning electron microscopes (SEM)
Explain how a transmission electron microscope works
A beam of electrons is transmitted through a specimen and focused to produce an image
What is the strength of using a transmission electron microscope
It has the best resolution of up to 0.5nm
Explain how a scanning electron microscope works
A beam of electrons is fired at the specimen and then the electrons that are reflected are collected.
What is the resolution of a scanning electron microscope
Between 3-10nm
What is the benefit to using a scanning electron microscope
Gives a 3D image
Which of a light microscope or an electron microscope
is cheapest
Light microscope
Which of a light microscope or an electron microscope is easier to use
Light microscope is small and portable
Which of a light microscope or an electron microscope has complex sample preparation
Light microscope
What can be a problem that occurs with sample preparation of an electron microscope
Can lead to sample distortion
Which of a light microscope or an electron microscope requires a vacuum
Electron microscope
Which of a light microscope or an electron microscope gives images in colour
Light Microscope
Electron microscope is usually in black and white
Which of a light microscope or an electron microscope has magnification up to x2000
Light microscope
Which of a light microscope or an electron microscope has a resolving power of 200nm
Light microscope
Which of a light microscope or an electron microscope requires the specimens to be dead
Electron microscope
Aside of light and electron microscopes what is the other main type of microscope
Laser scanning confocal microscope
How does a laser scanning confocal microscope work
It moves a single spot of a focused light across a specimen. This causes florescence from the components labelled with a dye. The light emitted from a specimen is filtered through a pinhole aperture forming an image
What is the benefit of using a laser scanning confocal microscope
Very high resolution
What are the two fundamental types of cell
Prokaryotic and eukaryotic
What is a prokaryote
A single celled organism
What is a eukaryote
Multicellular organisms
