Microscopy and Cell Biology Concepts

Resolution

clarity/detail of image

Contrast

difference between light and dark areas

Depth of field

how much is in focus at one time

Field of view

how much of the slide you can see

Working distance

space between lens and slide

Ocular lens

Eyepiece (10x magnification)

Objective lenses

4x, 10x, 40x, 100x (magnify specimen)

Stage

Holds the slide

Coarse Focus

Large movements (ONLY for low power!)

Fine Focus

Precise focusing (for 10x and up)

Light source

Illuminates specimen

Condenser

Focuses light on specimen

Iris diaphragm

Controls light intensity & contrast

Range

Highest value - Lowest value

Accuracy

how close your measurement is to the true value

Precision

how consistent/repeatable your measurements are

Beaker

Not very accurate, good for rough estimates

Graduated Cylinder

Very accurate, read at the meniscus

Erlenmeyer Flask

For mixing/stirring

Digital Scale

High accuracy

Ruler / Meter Stick

Use metric side (cm/mm)

Micropipette

Needs a tip; has 2 stops

Serological Pipet

More accurate than a beaker

Hypothesis

A testable statement/prediction

Independent Variable

What you change in the experiment

Dependent Variable

What you measure (the outcome)

Control Variables

What stays the same every time

Data

The info you collect

Quantitative

Measured in numbers (like heart rate)

Qualitative

Observed, not measured (like color or behavior)

Protein

chain of amino acids

Absorbance (A)

how much light is absorbed

% Transmittance (%T)

how much light gets through

Enzyme

specialized protein that acts as a biological catalyst by speeding up chemical reactions in living organisms. It does this by lowering the activation energy required for a reaction to occur.

Biological catalyst

(usually a protein) that speeds up chemical reactions without being used up.

Catalyst

Speeds up reactions.

Substrate

The molecule the enzyme works on.

Active site

Spot where substrate binds to enzyme.

Product

What the substrate becomes after the reaction.

Amylase

An enzyme that breaks down starch (substrate) into maltose (a reducing sugar).

Iodine test

Black with iodine = starch is still there = no enzyme activity.

DNS test

Red/orange with DNS = maltose is present = amylase worked.

Too cold

too hot

optimum temperature

enzyme slows down; enzyme denatures; maximum activity

Optimum pH for amylase

Around 7.

Cofactors

Helper molecules — some enzymes NEED them to function.

Diffusion

Movement of molecules from high → low concentration; no energy needed.

Osmosis

Diffusion of water through a selectively permeable membrane.

Hypertonic solution

More solute outside; water leaves cell → shrinks.

Hypotonic solution

Less solute outside; water enters cell → swells.

Isotonic solution

Equal solute; water moves equally → no net change.

Lysis

Animal cell that busts.

Dilution formula

C₁V₁ = C₂V₂.

Total magnification

ocular × objective.

Focus knobs

Coarse: 4x only; Fine: all others.

Oil immersion

100x.

Spirogyra (protist) →

Elodea (plant) →

Cheek (animal) →

Mold (fungi) →

Bacteria →

spiral chloroplasts; chloroplasts, wall; membrane, nucleus; hyphae, sporangia; Gram + = purple | Gram - = pink.

Standard curve

Absorbance (Y) vs. concentration (X) → Use unknown absorbance to find concentration.