Mini-Practical 1: Evolution, Antibiotic Resistance, and Prokaryotes

Vocabulary flashcards reviewing microevolution, macroevolution, mechanisms of natural selection, prokaryotic shapes, cyanobacteria, and disk diffusion sensitivity testing.

Biological Evolution

The process defined as 'descent with modification' of offspring, resulting in changes to a population over time.

Microevolution

Changes in allele frequency of a population over time that result in relatively small qualitative or quantitative changes in traits over a relatively few generations.

Macroevolution

The descent of different species from a shared common ancestor over many generations, involving changes in allele frequency over a long period of time.

Mutation

Any chemical change in the nucleotides or nucleotide sequences of genes; it serves as the ultimate source of variation in a population.

Migration (Evolutionary)

A mechanism of evolution where the allele frequency of a population changes because members of an existing population leave or new members join.

Genetic Drift

A change in allele frequencies due to purely random factors, which is most significant in small populations.

Natural Selection

A process in nature whereby survival and differential reproduction of individuals with greater evolutionary fitness are favored.

Fitness (Evolutionary)

A specific evolutionary term meaning successful reproduction (producing more offspring), rather than physical fitness or healthiness.

Speciation

The formation of a new species, which occurs when evolutionary mechanisms are coupled with reproductive isolation.

Reproductive Isolation

Mechanisms (such as geographical barriers like mountain ranges or islands) that isolate diverging populations to prevent gene flow and interbreeding.

Diploid Organisms

Organisms that have pairs of homologous chromosomes (two sets) and matching pairs of alternate genes (alleles).

Haploid Organisms (Bacteria)

Organisms that possess only a single set of chromosomes without homologous pairs, meaning they do not have alternate genes (alleles) to pair with.

Silent or Neutral Mutations

Genetic mutations that occur in cells without producing any measurable change in bacterial growth or physiological function in the presence of an antibiotic.

Coccus

A basic cell shape category of prokaryotes characterized by a spherical or round shape.

Bacillus

A basic cell shape category of prokaryotes characterized by a rod shape.

Spirillum

A basic cell shape category of prokaryotes characterized by a spiral shape.

Cyanobacteria

A major category of photosynthetic bacteria common in aquatic environments, including genera such as Gleocapsa, Oscillatoria, and Anabaena.

Heterocyst

A specialized cell found in cyanobacteria where nitrogen fixation occurs.

Disk Diffusion Antibiotic Sensitivity Test

A laboratory procedure in which solution-soaked paper disks are placed on a bacterial agar lawn to assess growth inhibition caused by diffusing chemicals.

Clear Zone (Zone of No Growth)

An area around a chemical-soaked disk on an agar plate where bacterial growth has been inhibited by diffusing antibacterial chemicals.

Control Variable (Disk Diffusion Test)

Water; tested in the disk diffusion assay to verify that antibacterial chemicals, rather than the water solvent, caused the observed inhibition of bacterial growth.

Disk Diffusion Test Results Plate

An agar plate demonstrates clear zones of inhibited bacterial growth surrounding paper disks dipped in Lysol, Isopropanol, and Bleach, compared to no clear zone around the Water control disk.