2.1 Cell structure Flashcards
(35 cards)
What is a light microscope?
A microscope that uses visible light to magnify and observe small objects or organisms that are living.
What are the advantages of light microscopes?
You can view specimens in colour.
You can view specimens in real time.
What are the disadvantages of light microscopes?
It has a low magnification (*1500)
It has a low resolution (200mm)
It is difficult to see organelles of the cell.
How do you calculate magnification?
Magnification = image size / Actual size
What can you see with a light microscope?
Even at maximum magnification, it is only possible to observe the larger features of the cells such as the nucleus or chromosomes during mitosis.
What are the two different types of electron microscopes?
Transmission electron microscope
Scanning electron microscope
How does a transmission electron microscope work?
It uses electrons to produce 2D image of the inside of a cell. they have a maximum magnification of *200,000
How does a scanning electron microscope work?
It uses a beam of electrons to produce 3D images of the outside surface of cells. they have a maximum magnification of *200,000
What are the advantages of electron microscopes?
Higher resolution and magnification capabilities
What are the disadvantages of electron microscopes?
You can only view dead specimens
Specimens can be viewed only in black and white
Expensive and need training to use them.
What is a laser scanning microscope?
it uses lasers to produce images at different depths within the cell.
What are the advantages of laser scanning microscopes?
You can view living cells in colour,
You can observe cells in real time,
Sections can be made through the cell either vertically or horizontally.
What are the disadvantages of laser scanning microscopes?
Magnification and resolution are low compared to electron microscopes,
require training to use them,
Expensive
What is magnification?
The number of times greater the image is then the specimen.
What is resolution?
The ability to distinguish between two points on an image. the higher the resolution, the sharper the image.
What are the different types of microscopes?
Light microscopes,
Transmission electron microscope,
Scanning electron microscope,
Laser scanning microscope
How do you prepare a microscope slide?
Take a thin slice of your specimen and place it onto a clean microscope slide, add a drop of water or stain onto the specimen, take a clean cover slip and lower onto the specimen, taking care to avoid air bubbles.
Why are stains used?
To highlight particular organelle, e.g. red blood cells and white blood cells.
To distinguish different tissue types, e.g. smooth muscle tissue.
How do you use an eyepiece graticule?
Line up the eyepiece graticule and the stage micrometer, using the *4 objective lens. Once lined up you can use it to measure objects on the microscope stage.
What is the function of the nucleus?
The nucleus is the control centre of the cell, responsible for storing and protecting the cell’s DNA, and regulating gene expression and cell activities.
What is the function of the nucleolus?
Ribosome production
What is the function of the nuclear envelope?
Separates the nucleus from the cytoplasm and regulate the passage of molecules in and out of the nucleus
What is the function of mitochondria?
Energy production and site of respiration.
What is the function of the Golgi body?
Protein modification and packaging.
