BIOL 107 LAB

Vocabulary flashcards covering microscope optics, experimental controls, cellular biology, spectrophotometry, dilution math, and antibiotic resistance.

Positive / Negative Control Group

Groups designed to test assumptions in an experiment

Trypan Blue

• Stain used to detect dead cells

• Can be toxic or carcinogenic.

How does bleach disrupt cell membranes?

By damaging cell membranes and denaturing proteins

How detergents destroy cell membranes

Amphipathic and cone-shaped molecules that disrupt cell membranes by wedging into the lipid bilayer

Ocular Divisions Method

The most accurate method to determine the actual size of a specimen, calculated by multiplying ocular divisions by $x\,\mu\text{m/ocular division}$.

Magnification of Drawing

The ratio calculated as $\frac{\text{size of drawing}}{\text{actual size of specimen}}$ .

Total Magnification

The overall magnification calculated as $\text{Mag}_{\text{ocular lens}} \times \text{Mag}_{\text{objective lens}}$.

Pure Culture

A group of genetically identical cells.

Medium

A growth solution that contains nutrients that help organisms grow.

Paramecium

• An organism that feeds by using cilia to propel food towards its oral groove

• Serves as a model for observing food vacuole movement.

Rotifers

A common contaminant in Paramecium cultures that feed by propelling food into their mouth structures.

Euglena

Motile, photosynthetic algae equipped with chloroplasts and flagella.

Contrast

The distinction of specimen details, which can be increased by using stains or decreasing the amount of light.

Dark Field Microscope

Directs light indirectly from below to illuminate the specimen from the sides, allowing light to enter the specimen indirectly.

Phase Contrast Microscope

Passes light around an annular ring, through a phase plate, and through the specimen, slowing the light that passes through the specimen.

Fluorescence Microscope

Light is reflected off a dichroic mirror and passes through a specimen, exciting it to release light back through the mirror into the ocular lens.

Resolution (R-value)

The minimum distance between two objects required for them to visibly appear as individual, separate objects.

Resolution Formula

The equation $\text{Resolution} = \frac{0.61\lambda}{\text{N.A}}$, where $\lambda$ is wavelength and $\text{N.A}$ is numerical aperture.

Numerical Aperture (N.A)

• Measures the ability of the microscope to gather light & resolve fine details

• Improves resolution when increased

• Can be increased by placing oil between the objective lens and the specimen.

C. elegans

Clear worms that glow when exposed to blue light because green fluorescent protein (GFP) is activated.

Depression Slide

A concave glass slide used to accommodate larger organisms such as Paramecium, rotifers, and amoeba.

Methyl Cellulose

A viscous substance added to microscope preparations to slow down an organism's movement.

Erythrosine B

A red dye used to see the food vacuoles inside Paramecium.

Autofluorescence

A protective mechanism where chloroplasts re-release excess light energy as light of a different wavelength under intense illumination.

Photobleaching

The damaging and fading of chloroplasts to a pale color due to overwhelming light, causing cells to become non-motile from stray electron damage.

Transmittance (T)

The ratio of transmitted light to incident light representing the amount of light that passes through a sample, expressed as a percentage.

Absorbance (A)

A quantitative measurement calculated as $-\log(\text{Transmittance})$.

Turbidity

The cloudiness or haziness of a fluid caused by suspended particles scattering light rather than absorbing it.

Optical Density (OD)

A measurement of turbidity at a specified wavelength describing the light scattered or absorbed to determine cell concentration in a pure liquid culture.

Stock Solution

A concentrated solution of known concentration.

Dilution (D)

A factor calculated as $\frac{\text{volume of original solution}}{\text{volume of original solution} + \text{volume of solvent}}$.

Diluted Concentration Formula

The relationship given by $C_D = C_U \times D$, where $C_U = \frac{C_D}{D}$.

Standard Curve

A reference curve specific to a particular pigment and solvent that cannot be extrapolated beyond its tested range.

Microbiota

The community of bacteria growing naturally on or inside our bodies.

Zone of Inhibition

The clear area around an antibiotic disc indicating where bacteria are either sensitive to or killed by the antibiotic.

Antibiotic Resistance Mechanisms

Strategies employed by bacteria to survive treatments: degrading/altering the drug, blocking drug influx into the cell, and pumping the drug out via efflux.

Tetracycline

A broad-spectrum antibiotic that inhibits bacterial protein synthesis.

Penicillin

An antibiotic used to treat gram-positive bacteria by inhibiting the enzyme responsible for linking NAG and NAM in the cell wall.

Chloramphenicol

A broad-spectrum antibiotic that inhibits bacterial protein synthesis, primarily restricted to treating pink eye due to widespread antibiotic resistance.

Colorimetric Assay

An experimental assay that measures color change and quantifies it as absorbance.

Crude Extract

A biological extract that has not been purified for one specific component.

Iodine

A chemical test used to detect starch, where a deeper blue color indicates a higher concentration of starch.

Betacyanin

A pigment with a maximum absorbance peak at $525\,\text{nm}$.

Assay

A laboratory procedure used to test for a particular process, chemical reaction, or substance.

DCPIP

An artificial electron acceptor that absorbs maximally at $620\,\text{nm}$ and turns colorless when reduced by electrons from the electron transport chain of Photosystem II.

Corrected Change In Absorbance Formula

Calculated as $\Delta\text{Absorbance} = \Delta\text{DCPIP+CP} - \Delta\text{Dark group} - \Delta\text{DCPIP} - \Delta\text{CP}$.

Aseptic Technique

Sterile practices that prevent contamination, including sterilizing surfaces, washing hands before and after lab work, minimizing exposure time, and working away from high-traffic or dusty areas.

Rate of Reaction

The speed of a chemical reaction calculated from the linear portion of a curve using $\frac{y_2 - y_1}{x_2 - x_1}$ . Use the 2nd linear portion because the first could be a lag phase.

Euglena

Motile algae with chloroplasts & flagella. Protect their chloroplasts with autofluorosence.

S.Cerevisae

A yeast that can ferment even when oxygen is present.

Applications of fermentation

Potential production of biofuels. How do we produce a lot of ethanol with as little substrate as possible?

What temperature does yeast metabolize sugars best at?

30°C

$$\frac{x}{1000ml}\cdot molarmass$$

Formula for creating a solution

Physiological growth curve

(exponential phase is the log phase, we use that for determining the rate of reaction)