BSC2010L Final Review: Core Concepts and Laboratory Techniques in Biology

Syllabus Review and Introductory Material

Course Overview and Lab Safety

• Course Content: Students are responsible for all material covered in the syllabus and introductory PowerPoint, including laboratory procedures and equipment operation.

• Lab Safety: Understand all safety protocols, including proper handling of chemicals, biological materials, and equipment. Always wear appropriate personal protective equipment (PPE) and follow disposal guidelines for biological and chemical waste.

Lab 1: Scientific Method and Laboratory Techniques

Scientific Method and Experimental Design

• Scientific Method: A systematic approach to inquiry involving observation, hypothesis formation, experimentation, and analysis.

• Hypothesis: A testable, falsifiable statement that predicts an outcome. Hypotheses must be falsifiable to allow for scientific testing.

• Variables:

  • Independent Variable: The factor manipulated by the experimenter.

  • Dependent Variable: The factor measured in response to changes in the independent variable.

  • Control: A standard for comparison that is not exposed to the experimental treatment.

Laboratory Equipment and Measurements

• Measuring Tools: Know how to use serological pipettes, micropipettes, and graduated cylinders for accurate liquid measurement.

• Spectrophotometer: Measures the absorbance of light by a solution at specific wavelengths. Used to determine the concentration of substances based on their absorption spectrum.

• Absorption Spectrum: A graph showing how a substance absorbs light across different wavelengths. Used to identify substances and determine concentrations.

• Standard Curve: A plot of known concentrations versus absorbance, used to determine the concentration of unknown samples.

Example: Using a standard curve, the concentration of an unknown protein solution can be determined by measuring its absorbance and comparing it to the curve.

Lab 2 & 3: Microscope Investigations

Microscopy Principles and Techniques

• Microscope Parts: Know the names and functions of components such as the ocular lens, objective lenses, stage, condenser, and coarse/fine focus knobs.

• Key Terms:

  • Magnification: The degree to which an image is enlarged.

  • Resolution: The ability to distinguish two points as separate.

  • Contrast: The difference in light intensity between the specimen and background.

  • Depth of Field: The thickness of the specimen that is in focus at one time.

  • Index of Refraction: A measure of how light bends as it passes through different media; affects image clarity.

• Microscope Techniques: Preparing wet mounts, using immersion oil for high magnification, and proper focusing methods.

• Calculations:

  • Total Magnification: Multiply ocular lens power by objective lens power.

  • Field of View Diameter: Used to estimate specimen size at different magnifications.

  • Unit Conversions: Be able to convert between meters, millimeters (mm), micrometers (μm), liters, milliliters (ml), and microliters (μl).

Cell Types and Organelles

• Prokaryotic vs. Eukaryotic Cells:

  • Prokaryotes: Lack a nucleus and membrane-bound organelles (e.g., Bacteria).

  • Eukaryotes: Have a nucleus and membrane-bound organelles (e.g., Plants, Animals, Fungi, Protists).

• Classification: Identify observed organisms as prokaryotic/eukaryotic, photosynthetic/non-photosynthetic, and note organelles present.

• Cell Size and Surface Area-to-Volume Ratio: Cell size is limited by the need for efficient exchange of materials; larger cells use adaptations (e.g., vacuoles in plants) to survive.

• Endosymbiont Theory: Explains the origin of mitochondria and chloroplasts as formerly free-living prokaryotes engulfed by ancestral eukaryotic cells. Evidence includes double membranes and their own DNA.

Lab 4: Diffusion and Osmosis

Principles of Diffusion and Osmosis

• Diffusion: The movement of molecules from an area of higher concentration to lower concentration (down a concentration gradient) until dynamic equilibrium is reached.

• Temperature: Higher temperatures increase the rate of diffusion.

• Osmosis: The diffusion of water across a selectively permeable membrane.

• Tonicity:

  • Hypertonic: Higher solute concentration outside the cell; water leaves the cell.

  • Hypotonic: Lower solute concentration outside the cell; water enters the cell.

  • Isotonic: Equal solute concentration; no net water movement.

• Effects on Cells:

  • Plant Cells: Prefer hypotonic environments (turgid); plasmolysis in hypertonic solutions.

  • Animal Cells: Prefer isotonic environments; lysis in hypotonic, crenation in hypertonic solutions.

  • Protists and Bacteria: Use contractile vacuoles or cell walls to manage osmotic pressure.

• Osmometer: Device used to measure solute concentration by observing water movement.

• Potato Experiment: Observing mass changes in potato slices placed in solutions of varying solute concentrations demonstrates osmosis.

Lab 5: Cellular Respiration and Fermentation

Metabolic Pathways and Measurement

• Fermentation Types: Alcoholic fermentation (produces ethanol and CO2) and lactic acid fermentation (produces lactate).

• Equations:

  • Aerobic Cellular Respiration: $\mathrm{C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP}$

  • Alcohol Fermentation: $\mathrm{C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2 + ATP}$

• Carbohydrates:

  • Monosaccharides: Simple sugars (e.g., glucose).

  • Disaccharides: Two monosaccharides linked (e.g., sucrose).

  • Polysaccharides: Long chains of monosaccharides (e.g., starch).

• Measuring Fermentation: Use of fermentation tubes to measure CO2 production as an indicator of fermentation rate.

• Cellular Respiration Measurement: Reduction and oxidation reactions are tracked; alternative methods include respirometers and oxygen probes.

• Factors Affecting Respiration: Temperature, substrate availability, and inhibitors can decrease the rate of cellular respiration.

Lab 6: Photosynthesis

Photosynthetic Processes and Analysis

• Autotrophs vs. Heterotrophs: Autotrophs produce their own food via photosynthesis; heterotrophs consume other organisms.

• Photorespiration: A process where O2 is fixed instead of CO2, reducing photosynthetic efficiency.

• Photosynthesis Equation: $\mathrm{6CO_2 + 6H_2O + light \ energy \rightarrow C_6H_{12}O_6 + 6O_2}$

• Photosynthetic Anatomy: Key structures include chloroplasts, thylakoids, stroma, and pigments. Light-dependent reactions occur in thylakoid membranes; Calvin cycle occurs in the stroma.

• Organisms Observed: Examples include S. obliquus (a green alga).

• Photosynthesis and pH: Uptake of CO2 during photosynthesis can increase pH in aquatic environments.

• Data Analysis: Compare algae exposed to light (photosynthesizing) versus dark (not photosynthesizing) conditions.

• Carbon Cycle: Photosynthesis removes CO2 from the atmosphere, incorporating it into organic molecules.

• Comparison with Cellular Respiration: Photosynthesis stores energy in glucose; respiration releases energy from glucose.

Lab 7 & 8: DNA Fingerprinting

Molecular Biology Techniques

• DNA Isolation and Quantification: Extraction of DNA from cells and measurement of concentration using spectrophotometry or fluorometry.

• Restriction Enzymes: Proteins that cut DNA at specific sequences, generating fragments of varying lengths based on sequence variation.

• Gel Electrophoresis: Technique to separate DNA fragments by size using an electric field in an agarose gel. DNA samples are loaded at the negative (cathode) end; smaller fragments migrate faster toward the positive (anode) end.

• Standard (Marker): A DNA ladder with fragments of known sizes used to estimate the size of sample fragments.

• Agarose Gel Preparation: Calculate % (w/v) and volume for gels; higher agarose concentrations resolve smaller fragments, lower concentrations resolve larger fragments.

• Interpreting DNA Fingerprints: Analyze band patterns to determine genetic similarities or differences.

Lab 9 & 10: Introduction to Genetics

Genetic Principles and Analysis

• Cell Cycle Phases: Identify stages in onion root tip cells: interphase, prophase, prometaphase, metaphase, anaphase, telophase. Estimate phase durations by counting cells in each stage.

• Genotype vs. Phenotype: Genotype is the genetic makeup; phenotype is the observable trait.

• Cell Division: Prokaryotic division (binary fission) vs. eukaryotic division (mitosis and meiosis).

• Generations:

  • P Generation: Parental generation.

  • F1 Generation: First filial generation (offspring of P).

  • F2 Generation: Second filial generation (offspring of F1).

• Punnett Squares: Used to calculate phenotypic ratios for monohybrid (one trait) and dihybrid (two traits) crosses.

• Dominant vs. Recessive Traits: Dominant alleles mask recessive alleles in heterozygotes.

• Homozygous vs. Heterozygous: Homozygous = two identical alleles; heterozygous = two different alleles.

• Yeast Life Cycle: Alternates between haploid and diploid stages via mitosis and meiosis.

• Recombination Frequency and Map Units: Calculate gene distances using recombination data; 1% recombination = 1 map unit.

• Sordaria Experiment: Ascospore color arrangements indicate crossing over during meiosis.

• Mitosis vs. Meiosis: Mitosis produces identical cells; meiosis produces genetically diverse gametes.

• Mendelian Laws:

  • Law of Segregation: Alleles separate during gamete formation.

  • Law of Independent Assortment: Genes on different chromosomes assort independently during meiosis.

Sample Table: Comparison of Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic Cells	Eukaryotic Cells
Nucleus	Absent	Present
Membrane-bound Organelles	Absent	Present
Cell Division	Binary Fission	Mitosis/Meiosis
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Additional info: Where the original review sheet listed only questions or brief prompts, academic context and definitions have been added for clarity and completeness. Equations are provided in LaTeX format as required.