OSU bio 1113 lab final

the first types of microscope to be developed were:

simple light microscopes - single lens magnified the specimen directly and produced an image using the light

commonly used microscope used in laboratories

standard compound brightfield microscope - specimen appears dark against a bright background

microscope base

the portion of the microscope that rests on the table and supports the microscope

microscope arm

the part that extends from the base and supports the lens systems and stage

microscope stage

the flat surface on which slides are placed for viewing

microscope mechanical stage

metal clips that hold the microscope slide in place with two adjustable knobs that control precise movement of speciman

microscope condenser

the lens positioned immediately below the stage; focuses light onto the specimen from the light source.

microscope light source

the electric bulb located on the base of the microscope, directly below the condenser

microscope rheostat

adjusts light intensity

microscope light switch

a switch that turns on the light source

microscope iris diaphragm

adjusts the amount of light reaching the specimen by moving the control lever left and right

microscope objectives

the set of lenses immediately above the stage

microscope nosepiece

the revolving component on which the objectives are mounted; it allows you to switch from lens to lens as necessary

microscope coarse and fine adjustment knobs

the knobs located on either side of the stage that are used to move the stage to bring the specimen into focus.

microscope oculars/eyepieces

the lenses at the very top of the microscope (the lenses closest to your eyes) which provide the final magnification of the specimen being viewed (10×)

4x objective lens

scanning lens

10x objective lens

low power lens

40x objective lens

high power lens

100x objective lens

oil immersion lens

microscope magnification formula

power of ocular lense x power of objective lense

Maximum magnification of a light microscope

1000x

microscope resolution

ability of a lens to separate or distinguish small objects that are close together

how does the size of a microscope lens change with increasing magnification?

lens size decreases

Why is immersion oil used?

Immersion oil is used with an oil immersion lens to reduce light loss between the slide and the lens

parfocality

microscope remains close in focus as it switches from objective to objective, minor adjustments with the fine focus knob may be necessary

why does the microscope field become darker with increasing magnification?

less light can penetrate through the lens

binocular dissecting light microscope

used for low magnification of plate cultures, or for structures that are viewed as live specimens and/or are too large to view under a standard compound microscope

total magnification of dissecting microscope

ranges from 10-25x or 7-30x

prokaryotic and eukaryotic cells are surrounded by a

cell/plasma membrane - regulates interactions of cell with environment

biological membranes are composed of

phospholipids, carbohydrates, and proteins

what purpose do phospholipids have in the cell membrane?

form a barrier that can prevent many substances from entering the cell

what purpose do proteins have in the cell membrane?

carry out specific functions

what purpose do carbohydrates have in the cell membrane?

cell recognition

which type of cells contain membrane-bound organelles?

eukaryotes

cell membrane functions

barrier, transport, organization, communication, recognition

barrier (cell membrane)

lipid bilayer prevents the entry into the cell of all substances except water, glycerol, and small lipid-soluble molecules

transport (cell membrane)

metabolites must be taken up by the cell and waste products eliminated; only water and small lipid-soluble molecules can be taken up by passive diffusion

facilitated diffusion

movement of specific molecules across cell membranes through protein channels

active transport

energy-requiring process that moves material across a cell membrane against a concentration gradient

organization (cell membrane)

provide a framework for the organization of enzymes and electron carriers in space so that these cell processes are carried out in an efficient manner

communication (cell membrane)

interaction with other body cells, foreign cells, or chemicals; contains receptors that initiate chemical reactions upon binding with hormones

recognition (cell membrane)

certain molecules on the surfaces of cells allow them to recognize other cells of

the same type. They also allow the organism to distinguish between its own cells and those "non-self" ("foreign")

semipermeable membrane

cell membrane that allows smaller molecules or molecules without an electrical charge to pass through it, while stopping larger or highly charged molecules

dialysis tubing

tubing with tiny holes to allow small molecules to pass through (semi-permeable); shapes into a tube when wet

why is it important that the dialysis tube is slightly limp at the beginning of the experiment?

so that molecules have room inside the bag to move into

why must the dialysis bag not be placed on anything absorbable?

it may cause water evaporation from the bag

in exercise 2, what was the positive control?

the substance originally put in the bag (known to show a result with added indicator)

in exercise 2, what was the negative control?

the substance originally put in the beaker (shows no result with added indicator)

how do we tell if water has entered/left the bag?

weigh the bag

what test is done for testing the presence of glucose?

benedict's test

interpret results of benedict's test

blue: absence of reducing sugar

green: some reducing sugars

orange: a lot of reducing sugars present

how do we test for the presence of salt in solution?

add silver nitrate

interpret results of silver nitrate test

precipitate forms: salt is present

precipitate does not form: salt is not present

how do we test for the presence of starch in solution?

add iodine -- turns blue/black

how do we test for iodine in solution?

add starch -- turns blue/black

diffusion

the process by which water, glycerol, and small lipid-soluble molecules enter the cell; a random movement of molecules that occurs in a fluid, gas, or solid

what direction do molecules move in diffusion?

higher to lower concentration

formula for rate of diffusion

rate = constant * sqrt(molecular weight)

osmosis

diffusion of a solvent (usually water) through a semi-permeable membrane when [solute] is different on the inside and outside of the barrier

diffusion of solvent is ______________ on the number of solute molecules, but ________________ of the chemical nature of solute

dependent; independent

hypotonic

concentration of solutes outside the cell is less than that inside; cell swells

hypertonic

concentration of solutes outside the cell is greater than that inside; cell shrinks

isotonic

concentration of solutes is equal on both sides of the membrane

What is lysing of cells?

cell fills with too much water, swelling and bursting open; occurs when cells are in severely hypotonic solutions

what types of cells may lyse?

animal cells; plant and most bacterial cells have cell walls that prevent lysing

crenation

shrinking of animal cells in severely hypertonic solutions due to the exiting of water from inside the cell

plasmolysis

cytoplasm and cell membrane of plant cells shrink away from the cell wall, but maintain original size and shape externally

turgidity

the pressure created by water pushing up against the plant cell wall

peroxidase enzymes

break down hydrogen peroxide into water

guaiacol

phenolic compound found in plants; clear when reduced, brown when oxidized against the superoxide anion

guaiacol can be detected with a

spectrophotometer

what is the substrate with peroxidase?

hydrogen peroxide

what type of curve does an absorbance vs. time graph have?

increases, then plateaus at a specific absorbance (kind of like a log graph)

how do you calculate rxn rate from an absorbance vs. time graph?

make a line of best fit, then calculate slope

how does increasing environment pH influence absorbance rate?

decreases it

photosynthesis reaction

6CO2 + 6H2O + light energy --> C6H12O6 + 6O2

aerobic respiration reaction

C6H12O6 + 6O2 -> 6CO2 + 6H2O

heterotrophic organisms

cannot make their own food and rely on other organisms for food

autotrophic organisms

are capable of harnessing energy from sunlight and using it to produce glucose, the main source of energy for the organism.

photoautotrophs

organisms that use light as a source of energy

chemoautotrophs

organisms that use inorganic molecules as their initial source of energy

where does photosynthesis take place?

chlorophyll containing chloroplasts

Why does chlorophyll appear green?

it absorbs red and blue light waves and reflects green light

lights reactions

H2O + light --> 1/2O2 + H2

dark reactions

CO2 + H --> carbohydrate

chromatography

a technique that is used to separate the components of a mixture based on the tendency of each component to travel or be drawn across the surface of another material.

in paper chromatography, which molecules move faster?

non polar

carotenoids

carotene and xanthophyll

mobile chromatography phase

the sample moves

stationary chromatography phase

the sample does not move

what part of a plant is continuously dividing?

the meristem

what happens during the s phase?

DNA replicates

prophase

nucleolus disappears and chromatin condenses to visible chromosomes

prometaphase

nuclear envelope dissociates and spindle fibers extend to the center; attaches to kinetochore

metaphase

chromosomes line up at metaphase plate

anaphase

chromosomes separate and move to opposite ends of the cell