Lab Exam 1 Flashcards
Labs 1-4
magnify definition
appear larger or smaller
resolution
the ability to distinguish 2 objects that are close together as being 2 separate objects, rather than just 1
contrast
happens when different parts of an object absorb or transmit different amounts of light
* some parts appear darker or lighter than others
What sizes are compound microscopes good for?
1/10 of a micrometer to a few mm
Eyepiece
can be moved apart or together
The right eyepiece has a pointer
Have a diopter ring to adjust the sharpness of the image
Eyepiece magnification is 10x
Nosepiece
has 4 objective lenses
Can be rotated to change objectives with different magnification (4x, 10x, 40x, and 100x)
How do you calculate total magnification?
eyepiece magnification x objective lens magnification
Mechanical stage
- Has a caliper that holds a slide in place
- Can move with stage controls
- Lower knob moves slide left to right
- Upper knob moves toward or away from you
Condenser
- Contains an iris diaphragm: can be opened to permit more light to illuminate the slide
- High magnification objectives - The diaphragm allows enough light to see objects clearly
- Contrast can be increased by closing down the diaphragm through a lever at the front of the condenser
- contrast
2 focusing knobs
- Coarse focus knob moves stage up or down
- Outer ring
- Fine focus knob moves stage up or down — - - only a SMALL distance
- 40x and 100x
- resolution
What is the size order and what magnifications were used?
Bacillus: 0.005 to 0.01 mm: 400x
Amoeba: 0.025-0.05 mm: 100x
33 hr chick embryo: 4.5 mm: 40x
What was the independent and dependent variable for lab 2 (Electrophoresis)
Independent variable: pH
Dependent variable: net electrical charge
Electrophoresis
a way to separate and identify proteins
What are the 3 categories of R-groups?
Non-polar
Polar
Ionic *matters for this lab
What are the 5 amino acids with an ionic R-group?
Aspartic acid
Glutamic acid
Lysine
Arginine
Histidine
Electrophoretic separation
- depends on net electrical charge of proteins
- If a protein has a net negative charge, it will go toward the positive pole of the field
- If it has a net negative charge, it will go toward the negative pole
- No net charge, will not move
Which acids have COOH in their R-groups? How do they act in low and high pH?
- aspartic acid and glutamic acid
- At low PH, they are not charged; their COOH groups are protonated
- At high pH, their COOH groups lose protons and acquire a negative charge (COOH +OH- → COO- + H2O)
Which acids have an amino (NH2) group in their R-groups? How do they act in low and high pH?
- lysine and arginine
- At low pH, they are positively charged; their NH2 groups are protonated (NH2 + H+ → NH3+)
- At high pH, their NH3+ groups lose protons and lose their charge (NH3+ + OH- → NH2 + H2O)
Describe a low-pH environment
- protons (H+) are abundant
- neutral atoms may gain a proton
- lower the pH, more positively charged a protein is
What does histidine have and how does it behave?
- imino group
- behaves similarly to lysine and arginine
Describe a high pH environment
- Hydroxide ions may react with positively charged amino acids, giving them a net charge of 0
- higher the pH, more negatively charged a protein is
isoelectric point
protein has no charge
How does a protein behave when it is in a solution above and below the isoelectric point?
- Protein in solution where pH below isoelectric point will be net positive charge (b/c lots of H+)
- Protein in solution where pH above isoelectric point will be net negative charge
Synapomorphy
a character or trait that is shared
ex. feathers in birds, hair on mammals
What is the difference between eukaryotes and prokaryotes?
Eukaryotes have a nuclear membrane and prokaryotes don’t
What are the 2 types of prokaryotes?
- archaea
- eubacteria
archaea
live in very salty, hot, or acidic environments
Permeable definition
makes it through phospholipid bilayer
eubacteria (3 types)
- Have peptidoglycan cell walls which keep them from bursting when water diffuses in
- Cocci - spherical
- Bacilli - rodshaped
- Spirilla - helical
What are the 2 types of eukaryotes?
- protists
- fungi
Lyse
cell bursts if too much water goes in
Hemolysis
lyse for red blood cells
What happens with a not-so-permeable cell?
- solute enters slowly
- lysis takes longer to occur (takes longer to become transparent)
What happens with a highly permeable cell?
- solute quickly diffuses in
- cell swells w/ water
- cell bursts
Which molecules pass through cell membranes easily and why?
lipid-soluble molecules (ones with CH3, CH2, CH groups) pass through cell membranes easily b/c they can dissolve in the lipids of the cell membrane
What are the independent (3) and dependent variables for lab 4 (membrane permeability)
Independent variables
Size of solute molecule
Net charge of solute particle
Lipid solubility of solute molecule
Dependent variable
Cell membrane permeability
What effect does the net electrical charge on a molecule (or atom) have on membrane
permeability? How do you know
- electrically charged particles cannot cross
the membrane - We know b/c NaCl did not lyse the cells which means they didn’t enter the cell
What is the relationship between CHn/OH and lipid solubility?
CHn/OH ratio is directly related to lipid solubility
