Bacterial Growth and Genetics - Video Notes

Vocabulary-style flashcards covering key concepts in bacterial growth, genetics, and horizontal gene transfer.

Binary Fission

Asexual reproduction by separation of a bacterial cell into two new cells; DNA replicates; chromosomes anchored to the membrane; septum forms and divides the cell.

Septum

The inward growth of the cell wall and plasma membrane that divides a bacterium during binary fission.

Generation Time

Time required for bacterial doubling; varies among bacteria.

Lag Phase

Bacteria adapt to the environment; little or no net growth.

Exponential Phase

Bacterial cell numbers increase exponentially.

Stationary Phase

Metabolites are depleted and bacteria stop growing; population remains constant.

Decline (Death) Phase

Cells die off as nutrients are exhausted and waste accumulates.

Nutrient Availability

Availability of nutrients such as carbohydrates, nitrogen, iron, etc., affects growth.

Temperature

Environmental temperature affecting growth; many bacteria grow best near 35 °C.

pH

Acidity/basicity of the environment that influences bacterial growth.

Oxygen Concentration

Amount of oxygen available, influencing whether bacteria are aerobic or anaerobic.

Water

Essential solvent for cellular processes; its availability affects growth.

Eukaryotic Genome

Diploid genome with 23 pairs of chromosomes (~2.9 x 10^9 base pairs) in humans and many eukaryotes.

Prokaryotic Genome

Haploid genome with a single circular chromosome (~5 x 10^6 base pairs) in bacteria.

Plasmid

Small extrachromosomal DNA that replicates independently and often carries advantageous genes.

Conjugative Plasmid (F Plasmid)

Plasmid encoding transfer enzymes (tra genes) and sex pili to mediate DNA transfer during conjugation.

R-Plasmid

Plasmid encoding antibiotic resistance genes; may also carry toxin or virulence genes.

Operon

Cluster of co-regulated genes under a single promoter; enables simultaneous expression of related functions.

Constitutive Expression

Genes essential for survival are expressed continuously.

Pathogenicity Island (PAI)

Large cluster of virulence factor genes on the chromosome; acquired via horizontal gene transfer.

Mutation

Spontaneous genetic change; frequency around 1 per 10^10 replications; can confer growth advantage.

Transposable Elements

DNA sequences that can move from one genomic location to another; found in prokaryotes and eukaryotes.

Insertion Sequence (IS)

Smallest transposable element with inverted repeats at ends and a gene for transposase.

Transposon

Complex mobile element carrying antibiotic resistance or virulence genes; can move within genome or between DNA molecules.

Transformation

Uptake of naked DNA by a bacterium and incorporation into its genome.

Competent

Capable of taking up exogenous DNA; naturally competent strains include Haemophilus influenzae, Streptococcus pneumoniae, Bacillus spp., Helicobacter pylori, and Neisseria spp.

Naturally competent strains

Bacteria that can take up exogenous DNA without manipulation (examples: H. influenzae, S. pneumoniae, Bacillus spp., H. pylori, Neisseria spp.).

Bacteriophage (Phage)

Virus that infects bacteria; can have lytic or lysogenic life cycles.

Lytic Cycle

Phage multiplies and causes lysis of the bacterial cell to release progeny phages.

Lysogenic Cycle

Phage DNA integrates into the host chromosome as a prophage and is replicated with the host.

Prophage

Phage DNA integrated into a bacterial chromosome during lysogeny.

Phage Typing

Using lysogenic phages to identify and differentiate bacterial strains; used in epidemiology.

Hfr Cell

Bacterium with F plasmid integrated into its chromosome; high-frequency recombination during conjugation.

F' Plasmid

Donor conjugative plasmid that carries a fragment of chromosomal DNA.

Conjugation

One-way transfer of DNA from donor to recipient through a sex pilus, mediated by a conjugative plasmid.

Antibiotic Resistance

Resistance developed by bacteria, often selected by antibiotic use; allows survival in presence of the drug.

Antigenic Variation

Changes in antigenicity of surface molecules to evade the immune response.

Phase Variation

Reversible on/off switching of gene expression, altering phenotype.