Unit C: Section 1.0 Flashcards
Who invented the microscope?
Hans and Zacharias Janssen
What was the first compound microscope comprised of?
Used 2 lenses, an eyepiece and an objective lens
What is a compound microscope?
Using more than one lens to magnify an object
What was the magnifying power of the Janssens microscope?
20X
Who created the second microscope ever?
Robert Hooke
What was different between the Janssens and Hooke microscope?
The Hooke microscope used 3 lenses and the Janssens microscope used 2 lenses
Describe how the Hooke microscope worked
Used three lenses. Illuminated by a beam of light concentrated on a specimen by passing the light through a water-filled flask
What was the added lense in the Hooke microscope?
A “field lens” that passes light rays in a straight. Allowed for better conservation of light
What did Robert Hooke publish?
A micrographia containing 38 illustrations of plant, animal, and non-living objects that he viewed through a microscope
What were the unusual properties of cork?
- Lightweight
- Could float on water
- Firm,
What were the air pockets in corks referred to as?
Cells because they resembled the places that monks lived in
What did the cork consist of?
Air pockets surrounded by a thin mesh of fibre. They were actually remnants of living cells
Who created the single lens microscope?
Antonio van Leeuwenhoek
What did the single lens microscope resemble?
A magnifying glass
What did Antonio van Leeuwenhoek see under his microscope?
Movement of single cells known as bacteria, sperm, and single cell protoza’s
How were the single cells observed by Leeuwenhoek described as?
Animalcules. Individual Free living cells surviving as independant systems
What were the sizes of Leeuwenhoek’s microscopes?
Small, about the size of a palm and held directly to the eye
What was the magnification of Leeuwenhoek’s microscopes?
250X
Why did Leeuwenhoek have lots of success?
They produced clear images without a halo light
What caused the blurry images within a microscope?
-Result of light being scattered as it passed through the different lenses
What did achromatic lenses do?
- Controlled the halo of light
- Improve detail
What are the parts of the microscope?
- Eyepiece/ocular lens
- Coarse adjustment knob
- Fine adjustment know
- Revolving nosepiece
- Objective lenses
- Stage
- Stage clips
- Diaphragm
- Lamp or mirror
- Arm
- Base
What was the function of the eyepiece?
To look through or observe specimen
What was the function of the Coarse adjustment knob?
To move stage up or down
What was the function of the Fine adjustment knob?
To bring the object into a sharper focus and produce a clear sharp image
What was the function of the Revolving nosepiece?
To change magnification lens
What is the function of the objective lens?
To increase magnification
What was the function of the Stage?
To hold/support specimen
What was the function of the Stage Clips?
To hold slide in place
What was the function of the Diaphragm?
Adjust diameter of the opening
What was the function of the Lamp or Mirror?
To direct light towards a specimen
What was the function of the arm and base?
To provide support when holding
What is Spontaneous generation?
The idea that life could emerge spontaneously from non-living matter
How did they believe that you could make mice?
By combing wheat and sweaty underwear for 21 days
How did Francesco Redi attempt to disprove spontaneous generation?
He exposed meat in varied conditions. Only the meat that was fully exposed did the flys lay maggots on
How did John Needham try and prove that Spontaneous Generation existed?
He boiled chicken broth put it in a flask and sealed it. Because he boiled he believed that all the microorganisms were dead but the broth still went bad.
What did Needham suggest?
There was a life force that produced spontaneous generation
What was stated against Needham’s observations?
That his broth wasn’t sealed off and that there is bacteria in the air
How did Louis Pasteur disprove spontaneous generation?
He boiled broth and put it in an ‘s’ shaped flask so that air could reach it but the bacteria got caught in the bend of the ‘s’
Who discovered the nucleus?
Robert Brown
What was the nucleus described as?
Opaque granular spots within the cell
What did M.J Schleiden state about the nucleus?
It was the structure responsible for the development of the cell
What did the cell theory state?
- All living things are made up of one or more cells
- All living functions take place in the cell, making them the smallest unit of life
- All cells are produced from preexisting cells through the process of cell division
What are neither living or non-living cells?
Subcellular cells like viruses and prions
What do light microscopes use to magnify cells?
One or more curved lenses and a light source
What is the maximum magnification a light microscope can have?
1000-2000X
What are the 3 factors that affect what can be seen through a microscope?
- Magnification
- Contrast
- Resolution
What is brightfield?
When light passes directly through cells and all the cells appear colourless
What did scientists create to improve the contrast of the cell?
They created stains
How did stains work?
Particular stains attached to particular parts of the cell improving the contrast between the structures
What is a disadvantage of staining cells?
It kills the cells so it is not possible to see living cells
What is resolution?
The ability to distinguish between two structures that are very close together
How small can the human eye distinguish objects?
0.1 mm or larger
Why is the efficiency of a microscope limited?
Because as light is focused into small diameters it become blurred
What is the limit of resolution in a standard light microscope?
0.2 microns
Why do some organelles appear lighter or darker in images?
Because they change the speed and direction of light more than others can
How do fluorescence Microscopes work?
They use fluorescent substances to attach to molecules in tissue. When subjected to different types of lights they would glow
How does a confocal microscope work?
A laser concentrates light onto a specimen. Then the light is concentrated through a confocal pinhole. It reaches an electronic detector that converts light into an image
How does a confocal microscope produce a clearer image?
It only allows light that is in focus to pass through the confocal pinhole
Which microscope can produce 3D images?
Confocal microscopes
Why can a Confocal microscope produce?
Because every image formed is a very thin section of the specimen. Each image is stored in a computer and every image can be combines
What is a positive to green fluorescent protein?
It does not kill the cell when it stains it
What are the 3 types of electron microscopy?
- Electron Microsope
- Transmission Electron Microscope
- Scanning Electron Microscope
How does an electron microscope work?
Uses a beam of electrons instead of light and is able to produce images in fine detail
How is an image formed in an electron microscope?
The image is formed by the absorption or scattering of the electron beam because of electron-dense material that does not let electrons pass through
How is focussing done on an electron microscope?
By adjusting of the electromagnets
How does a Transmission Electron Microscope work?
Passes electrons through a very thin section of a cell. The electrons that pass through fall on a fluorescent screen
What is the magnification and resolution of TEM?
1 500 000X
2.5 nm
How does a Scanning Electron Microscope work?
- Specimens are covered with electron-dense material like gold which reflects electrons
- Electrons bouncing off the surface are picked up by the sensor and a three-dimensional image is formed
What is the magnification and Resolution of a SEM?
300 000X
20nm
What are micrographs?
Photographs taken by either scanning or transmission electron microscopes
What is a drawback of the TEM?
- Difficulty building up a three-dimensional image
- All specimens are dead
- Must be operated in a vacuum
What are the smallest units of measurement in ascending order?
Micrometer/Micron
Nanometer
Angstrom
How many microns or micrometres are in 1 millimetre?
1000
How many nanometers are in 1 micrometre/micron 1000
1000
What types of microscopes allow scientists to view images of molecules?
The Scanning Tunnelling microscope and the Atomic Force Microscope
What type of system are cells?
Open systems because they exchange and matter with their environment
How do cells communicate with each other?
- Messenger molecules from cells travel through the bloodstream and attach to receptor molecules on the target cell.
- The receptor cells trigger a chain reaction to carry the message into the proper place inside the cell
What does X-Ray crystallography do?
Analyzes patterns of molecules to help scientists to understand what molecules look like
What is the source of a light microscope vs an electron microscope?
Lamp or laser vs Electron Gun
What is the source of a radiation on a light microscope vs an electron microscope?
UV or Visible light vs Electron Beam
What is the lense of a light microscope vs an electron microscope?
Curved glass surface vs Electromagnets
What is the receiver of a light microscope vs an electron microscope?
Eye or digital image vs Fluorescent screen or digital image
What is the focus of a light microscope vs an electron microscope?
Up and down movement of the lenses vs adjustment of the magnetic field
