Basic components of living systems Flashcards
How expensive are light/optical microscopes, Scanning electron microscope, Transmission electron microscope
Light - inexpensive to purchase and operate
SEM & TEM - Expensive to purchase and operate
What radiation is used in each type of microscope
Light - light
SEM - Beams of electrons
TEM - Beams of electrons
What is the size of each type of microscope
Light - Small & portable
SEM - Large
TEM - Large
Maximum magnification of each type of microscope
Light - x1500
SEM - x100,000
TEM - x500,000
Maximum resolution of each type of microscope
Light - 200nm
SEM - 0.2nm (newer ones can go up to 0.1nm)
TEM - 0.1nm
Type of image produced in each type of microscope
Light - 2D
SEM - 3D
TEM - 3D
Sample preparation of each type of microscope
Light - simple
SEM - More complex but does not have to be as thin as TEM
TEM - Extremely thin and complex
Is a vacuum needed for each microscope
Light - No - can view living species
SEM & TEM Use o- Yes - sample must be dead
Explain the function and utility of gram staining
- Used to distinguish between two types of DNA - Gram-positive and Gram-negative bacteria
- Gram-positive bacteria is susceptible to penicillin which inhibits the formation of cell walls, gram negative bacteria have thinner cell walls and are not susceptible to penicillin - think of possible implications and uses therefore
How do you carry out gram staining
- Apply Crystal violet on bacterial specimen on slide
- Apply iodine to fix the dye
- Wash slide with alcohol, gram-positive bac will retain the dye and appear blue/purple under a microscope. The Gram-negative bac will lose the dye due to their thinner cell walls
- Apply Safranin dye (acts as a counter-stain) - makes gram-negative bac appear red
- Gram-positive = blue/purple
- Gram-negative = red
Explain the function and utility of Acid-fast staining
- Used to differentiate between species of mycobacterium from other bacteria
How do you carry out acid-fast staining
- lipid solvent used to carry carbol fuchsin dye into cells
- Cells washed with dilute acid - alcohol solution
- Mycobacterium are not affected by the alocohol solution and retain the carbol fuchsin dye - appearing red
- Other bacteria lose the stain and are exposed to methylene blue (counter-stain) making them appear blue
- Mycobacterium - bright red
- Other bacteria - blue
Magnification formula
Magnification = Image size/ object size
Units
nm x1000 = micrometre x1000 = mm x10 = cm x 100 = M
What is the difference between magnification and resolution
Magnification = how large the image is compared to actual size Resolution = The ability to distinguish between two distinct points on an image - the amount of detail
Structure of nucleus
Contains: Double nuclear envelope Nuclear pores Nucleolus Chromatin
Function of nucleus
Nucleus - contains DNA (chromatin) which controls activity of cells and also allows replication and copy for cell division, Attached to rough endoplasmic reticulum allowing MRNA to go to ribosome for protein synthesis
Nucleolus - Made by RNA and protein - produces ribosomes
Nuclear envelope - Double membrane - compartmentalises DNA - protecting it from damage
Nuclear pores - Allows molecules to enter and leave nucleus