📊 Lab Methods &amp; Biostatistics

Scientific Method

A process of asking a question, forming a hypothesis, testing it with experiments and drawing conclusions.

Hypothesis

A testable explanation for an observation that can be supported or refuted by evidence.

Variables

The independent variable is changed, the dependent variable is measured and controlled variables are kept constant.

Control Group

A group that does not receive the treatment, used as a baseline for comparison.

Light Microscope

Uses lenses and visible light to magnify specimens up to about 1500 times.

Magnification and Resolution

Magnification enlarges an image, while resolution is the ability to distinguish two close points.

Scale Bars and Calculations

Actual size equals image size divided by magnification, a key skill in microscopy.

Staining Techniques

Dyes such as iodine and methylene blue increase contrast so cell parts are visible.

Measuring and Units

Biology uses metric units such as millimetres, micrometres and nanometres for tiny structures.

Lab Safety

Following procedures for glassware, chemicals, biological samples and disposal prevents accidents.

Tables and Graphs

Data are recorded in tables and plotted as line graphs, bar charts and scatter plots.

Mean, Median and Mode

Measures of central tendency summarising a data set.

Reliability and Validity

Reliable results are repeatable; valid results measure what they claim to measure.

Sampling

Selecting a representative subset of a population to study using methods such as random quadrats.

Ethics in Research

Experiments involving humans or animals must follow consent, welfare and honesty guidelines.

Intermediate topics (18)

Electron Microscopy

TEM and SEM use electron beams to achieve resolution thousands of times better than light microscopes.

Cell Fractionation

Homogenising and centrifuging cells to separate organelles by density.

Chromatography

Separates mixtures, such as pigments, by their different movement through a stationary phase.

Colorimetry

Measures the colour intensity of a solution to estimate concentration.

Spectrophotometry

Determines how much light of a given wavelength a sample absorbs, linked to concentration by the Beer-Lambert law.

Aseptic Culture Technique

Sterile handling prevents contamination when growing microbes or cells.

Serial Dilution

Stepwise dilution of a sample by a constant factor to obtain countable concentrations.

Quadrats and Transects

Standard sampling tools used to estimate species abundance and distribution along gradients.

Mark-Release-Recapture

Estimates population size using the ratio of marked individuals recaptured in a second sample.

Standard Deviation

A measure of spread showing how far values typically lie from the mean.

Standard Error and Error Bars

The standard error reflects the precision of a mean and is often displayed as error bars.

Correlation and Causation

Two variables moving together does not show that one causes the other.

Chi-Squared Test

Compares observed and expected counts, for example testing Mendelian ratios.

t-Test

A test for significant differences between the means of two groups.

Null Hypothesis

The default assumption of no effect or difference, which data may lead us to reject.

Immunofluorescence

Fluorescent-labelled antibodies reveal the location of proteins in cells and tissues.

ELISA

An antibody-based assay that detects and quantifies proteins or antibodies in samples.

Flow Cytometry

Cells pass through a laser one at a time and are counted and characterised by fluorescent markers.

Advanced topics (18)

Confocal Microscopy

Uses pinholes to remove out-of-focus light, giving sharp optical sections of thick specimens.

Super-Resolution Microscopy

Techniques such as STORM and STED beat the diffraction limit to image structures down to tens of nanometres.

Fluorescent Proteins

GFP and relatives let researchers tag and watch proteins in living cells.

FRET

Energy transfer between two fluorophores reports on molecular distances and interactions.

Mass Spectrometry

Measures mass-to-charge ratios to identify and quantify proteins and metabolites.

NMR in Biology

Nuclear magnetic resonance reveals structures and dynamics of molecules in solution.

Statistical Power

The probability of detecting a true effect, determined by sample size, effect size and variability.

P-Values and Multiple Testing

P-values give the probability of data under the null; corrections like Bonferroni control false positives across many tests.

ANOVA

Compares means across three or more groups by partitioning variance.

Regression Analysis

Models the relationship between variables, predicting a response from one or more predictors.

Bayesian Statistics

Updates probabilities for hypotheses using prior knowledge and observed data.

Experimental Design

Randomisation, replication, blocking and blinding reduce bias and confounding.

Meta-Analysis

Combines results from many studies to estimate an overall effect size.

Reproducibility in Science

Open data, preregistration and clear methods help others verify findings.

Bioimage Analysis

Software tools segment and quantify cells and structures in microscopy images.

Phylogenetic Statistics

Bootstrap and posterior probabilities measure confidence in the branches of evolutionary trees.

Model Organisms

Species like E. coli, yeast, Arabidopsis, zebrafish and mice are used because they are tractable and informative.

Laboratory Automation

Robotics and high-throughput screening let thousands of experiments run in parallel.