Hinkins' Revision Sheet 2 Flashcards
(40 cards)
Define magnification.
The number of times bigger an image is than the object.
Define resolution.
The ability to distinguish two close together objects as separate objects.
The detail that can be seen.
What is staining?
Staining is done to improve contrast in a preparation
Eg it can allow you to see specific organelles.
Outline light microscopes.
Uses light as its radiation.
Maximum magnification = 1500x
Maximum resolution = 200nm
Advantages of light microscopes.
Can view live specimen In colour Light focused by glass lenses No vaccum Unlikely to distort sample / introduce artefacts.
Outline electron microscope.
Uses electron beam as its radiation.
Maximum magnification 500,000x
Maximum resolution 0.1nm
Disadvantages of electron microscope?
Can only view dead specimen
In black and white
Sample must be in a vacuum
Complex slide preparation (more likely to distort sample / introduce artefacts)
Outline transmission electron microscope.
Electrons fired at a very thin section of sample. Electrons that pass through the sample are detected on a screen behind the sample. 2D image (v high magnification and resolution).
Outline scanning electron microscope.
Electrons bounce off a sample’s surface and hit detector.
Allows a 3D image (but slightly lower magnification and resolution than TEM).
How to calculate magnification?
Magnification = image / actual size
How to calculate actual size?
Actual size = magnification / image
How to calculate image size?
Image size = actual size x magnification
How to convert nm to mm?
Times image size by 1,000,000
How to convert ym to mm?
Times image size by 1000
Outline the nucleus.
Large, membrane bound organelle that contains genetic material in chromosomes.
What is the nucleolus?
Dark staining region of the nucleus. Associated with the formation of ribosomes and ribosomal RNA.
What is the nuclear envelope?
Double membrane around the nucleus. Contains nuclear pores so that mRNA can leave the nucleus.
What is a ribosome?
The organelle where protein synthesis takes place.
What is the RER?
Transports proteins made in ribosomes on its surface.
What is the SER?
Involved in lipid metabolism.
What is the Golgi apparatus?
Modifies proteins from the RER (eg by adding carbohydrates to them to make glycoproteins) and packages them into vesicles for secretion.
What are mitochondria?
Site of ATP production by aerobic respiration. ATP is required for energy.
What are lysosomes?
Contains digestive enzymes to break down pathogens and old cells and organelles.
What is the plasma membrane?
Separates cell’s contents from outside environment. And controls what enters and leaves the cell.