LAB EXAM Flashcards
Compound Light Microscope Parts
Magnification def
Apparent increase in size of the specimen
Resolution def
Ability to distinguish two objects that are close together
Contrast def
Ability to distinguish an object from its background
Compound Light Microscope parts: eyepiece
- AKA Ocular lens
- Magnifies image by 10x
- Does NOT help resolution
- May include pointer
Compound Light Microscope parts: Objective lenses
- Magnify AND increase resolution
SCANNER: 4x (find object)
LOW POWER: 10x (examine larger features)
HIGH POWER: 40x (detailed examination)
Microscope parts: Coaxial Corse & Fine Focus Knob
- Moves stage up and down
- Corse focus: use only w/ scanner and low power lens
Microscope parts: Coaxial Stage Motion Knob
- Large part at top = front and back
- Small part at bottom = side to side
Compound Light Microscope parts: Condenser
- Focuses light from lamp
- Adjustment knob moved it up or down
- Aperture iris diaphragm: controls angle (contrast)
- Held in place and centered by centring screws
Microscope parts: Field iris diaphragm
- Part of the lamp
- Controls the width of the beam of light
- Adjust contrast
How to calculate Magnification
Ocular lens x objective lens
10x40=400x
Parfocal System
Field of view will remain in focus as you change objective lense
Depth of Focus
- Distance between lens and object required for image to be in focus
- AKA working distance
- Larger for 4x and very narrow for 40x
Field of view size for each lens
- Scanner: 4x: 5mm (i.e. 10/4 of low power)
- Low power: 10x: 2mm (i.e. 4/10 of scanner)
- High Power: 40x: 0.5mm (i.e. 1/4 of low power)
- 1mm = 1000 microns µm
Brownian Movement
- The continuous RANDOM movement of particles in water
- Robert Brown
Diffusion
- NET movement of particles from an area of high concentration to an area of low concentration
- They move down the concentration gradient
- We say NET movement because some particles may go towards more concentration, but the total net movement is towards lower concentrations
Heavy vs light molecule diffusion
- Light molecule travels faster because it requires less kinetic energy to move its light load.
- Size, shape, temperature also affect how fast a molecule will diffuse.
How can materials PASSIVELY enter or exit a cell?
- Diffusion through the phospholipid bilayer
- Facilitated Diffusion (through channels or carrier proteins)
- Passive does not cost the cell any energy
How can materials ACTIVELY enter or exit a cell?
- Active transport
- Cytosis
Diffusion in or out of cells
- Phospholipid bilayer is semi-permeable
- CO2 and O2 and H2O (slowly) can pass via DIFFUSION
*
Osmosis
Diffusion of H2O across a selectively permeable membrane
Channel Proteins
- Provide an opening in the phospholipid bilayer through which specific small molecules can diffuse
- Uses NO ENERGY
- Can be gated
- Aquaporin: a channel protein for water
Carrier Protein
- Pick up a specific molecule on either side of the phospholipid bilayer and brings it across
- No energy used
- Also diffusion (because goes from an area of high concentration to one of lower concentration
Active Transport
- Will move molecules to a desired side of the phospholipid bilayer regardless of concentration gradient.
- Requires energy from the cell
- Cell can maintain higher or lower concentration than environment



