General Biology Laboratory: Enzymes, Transport, Microscopy, and the Scientific Method

Vocabulary practice flashcards covering enzyme kinetics, cellular transport mechanisms (diffusion and osmosis), microscopy techniques and metric conversions, and the scientific method.

Metabolism

The totality of an organism's chemical reactions, consisting of catabolic (energy-releasing) and anabolic (energy-storing) pathways that manage material and energy resources.

Metabolic Pathway

A series of sequential chemical reactions in a cell catalyzed by enzymes, in which a starting molecule is altered through multiple steps into a final product.

Catalyst

A substance that speeds up a chemical reaction and remains chemically unchanged and unconsumed at the end of the reaction.

Enzyme

A biological macromolecule that acts as a catalyst by speeding up a reaction without being consumed, acting specifically with a single reactant substrate.

Activation Energy ($E_A$)

The initial investment of energy required to contort reactant molecules so bonds can break and reach the transition state; this barrier is lowered by enzymes.

Active Site

The specific region on an enzyme where substrate molecules bind and interact, and where catalysis takes place.

Lock-and-Key Model

An enzymatic model proposing that the enzyme functions as a lock and the substrate functions as a key that precisely fits into the active site to initiate a reaction.

Induced Fit

The conformational change in shape that an enzyme undergoes when reactant molecules bind to its active site, tightening the fit around the substrate.

Denaturation

The unfolding of an enzyme's three-dimensional protein structure caused by extreme temperatures (above optimal) or pH changes, leading to a loss of biological catalytic activity.

Cofactor

A non-protein molecule, such as a metal ion or a small organic molecule (coenzyme like vitamin $B_3$), required by an enzyme for normal catalytic function and transition state stabilization.

Free Radical

An unstable, highly reactive atom or group of atoms missing an electron from a pair that causes cell damage by stealing electrons from adjacent molecules in a cascading reaction.

Superoxide Dismutase

An enzyme that catalyzes the destruction and neutralization of toxic superoxide anion free radicals by converting them into hydrogen peroxide ($H_2O_2$).

Guaiacol

A chemical dye substrate that acts as an indicator in peroxidase experiments, changing from colorless in its reduced state to brown as it is oxidized.

Spectrophotometer

A scientific instrument that quantifies the intensity of color by measuring the amount of light of a specified wavelength transmitted through or absorbed by a liquid medium.

Cuvette

A specialized square or round small tube made of optical glass or plastic used to hold sample solutions inside a spectrophotometer.

Phospholipid

A lipid molecule composed of a hydrophilic (water-attracting) phosphate head and two hydrophobic (water-repelling) fatty acid tails that form the structural foundation of biological membranes.

Dehydration Synthesis (Lipids)

The condensation reaction that removes water molecules to link glycerol to three fatty acid chains, forming ester bonds and producing a triglyceride.

Passive Transport

The movement of substances across a biological membrane down a concentration gradient (from high to low concentration) without expenditure of cellular energy.

Diffusion

The net movement of solute particles from an area of higher concentration to an area of lower concentration across a selectively permeable membrane until equilibrium is achieved.

Facilitated Diffusion

A passive transport process that allows polar or charged substances to cross a cell membrane down their concentration gradient via specific transmembrane transport proteins.

Active Transport

The energy-requiring movement of substances across a biological membrane against their concentration or electrochemical gradient, fueled by $ATP$.

Sodium-Potassium Pump

An active transport membrane protein system in animal cells that expels sodium ions ($Na^+$) from the cytoplasm and imports potassium ions ($K^+$) using $ATP$.

Dialysis Tubing

A semi-permeable artificial membrane containing microscopic pores that permits small molecules (like $NaOH$) to pass while restricting larger molecules (like phenolphthalein).

Osmosis

The passive diffusion of water (solvent) across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Tonicity

The relative solute concentration of an extracellular solution compared to the intracellular cytosol, determining the direction and extent of net water movement.

Isotonic Solution

A solution having an equal concentration of solutes compared to another solution or cell, causing zero net movement of water.

Hypertonic Solution

A solution that has a higher solute concentration and lower water concentration compared to another solution or cell, causing water to flow out of the cell.

Hypotonic Solution

A solution that has a lower solute concentration and higher water concentration compared to another solution or cell, causing water to rush into the cell.

Plasmolysis

The osmotic shrinkage of a plant cell's protoplast away from its rigid cell wall when placed in a hypertonic environment.

Crenation

The cellular shrinking and formation of spiny notches exhibited by red blood cells when water exits them in a hypertonic solution.

Meniscus

The curved surface of a liquid column in glassware caused by surface tension, read at the bottom of the curve at eye level.

Tare

The zeroing function on an electronic balance that offsets and subtracts the weight of an empty container (weigh boat or paper) before adding a substance.

Base Units (SI)

The foundational units of the metric system: meter ($m$) for length, gram ($g$) for mass, liter ($L$) for volume, and Celsius ($^\circ\text{C}$) for temperature.

Scientific Notation

A mathematical method of expressing very large or small numbers in the format $a \times 10^b$, where $1 \le a < 10$ is the coefficient and $b$ is an integer exponent.

Occhiolino

The historical name ('little eye') given by Galileo Galilei to his 1609 compound microscope design that featured three biconvex lenses.

Dissecting Microscope

A low-power microscope (up to $70\times$ magnification) used to view larger, three-dimensional specimens such as hair, insects, or whole tissue organs.

Compound Light Microscope

An optical microscope that uses visible light and a two-lens magnification system (ocular and objective lenses) to observe thin specimen sections up to $1000\times$.

Coarse Adjustment Knob

The large microscope knob that rapidly moves the stage up and down to bring the specimen into view; it must only be utilized with the scanning ($4\times$) and low-power ($10\times$) objectives.

Fine Adjustment Knob

The small knob located concentrically with the coarse adjustment used for precision focusing, especially under high-power ($40\times$) and oil immersion ($100\times$) objectives.

Total Magnification

The overall power of magnification calculated by multiplying the ocular lens power ($10\times$) by the objective lens power ($4\times$, $10\times$, $40\times$, or $100\times$).

Depth of Field

The vertical thickness or depth of a specimen plane that remains sharp and in focus under a particular microscope magnification.

Wet Mount

A temporary glass slide preparation where a fresh specimen is placed in a droplet of water and overlaid with a coverslip at an angle to avoid air bubbles.

Wicking

The technique of introducing a stain under a coverslip by applying a drop of stain to one edge and pulling it across the specimen using absorbent paper (like a Kimwipe) at the opposite edge.

Oil Immersion Lens

The $100\times$ objective lens designed to function with immersion oil to bridge the gap between lens and slide, reducing light refraction and increasing resolving power.

Scientific Method

A structured, repeatable procedure for problem-solving and natural investigation consisting of observation, question, research, hypothesis, experimentation, data analysis, conclusion, and communication.

Hypothesis

A testable, educated explanation or prediction framed in response to an observation, commonly structured as a measurable 'If…then…' statement.

Independent Variable

The experimental factor deliberately altered or manipulated by the experimenter (the hypothesized cause) and plotted on the x-axis of a graph.

Dependent Variable

The factor that is measured or observed for changes in response to the independent variable (the hypothesized effect) and plotted on the y-axis of a graph.

Control Group

The baseline group in an experiment that does not receive the experimental treatment and serves as a standard for comparison.

Experimental Group

The group of subjects in a scientific investigation that is exposed to the specific condition or treatment being tested.

Peer Review

The evaluation process where scientific research is scrutinized and vetted by independent expert peers before publication to verify experimental design, validity, and significance.

Graminivore

An herbivorous animal that feeds primarily on grasses, exemplified by the ground-dwelling Gelada baboon of Ethiopia.

Resting Heart Rate

The baseline pulse count measured per minute while an individual is completely relaxed and inactive, used as the control measurement in physical exercise kinetics.