Bacterial Genetics

Flashcards covering the fundamentals of bacterial genetics, including nucleic acid structure, replication, transcription, translation, genetic transfer mechanisms, and mutations.

Nucleic acids

Biological molecules essential for life that allow organisms to transfer genetic information from one generation to the next.

DNA (Deoxyribonucleic acid)

A double-stranded molecule that stores genetic information as a sequence of nucleotide bases: adenine, thymine, guanine, and cytosine.

Nucleotides

The basic structural units of DNA consisting of a nitrogenous base, deoxyribose sugar, and a phosphate group.

RNA (Ribonucleic acid)

A single-stranded nucleic acid composed of ribose sugar that uses uracil instead of thymine; types include mRNA, rRNA, and tRNA.

mRNA (Messenger RNA)

The template that carries DNA gene sequences to ribosomes, which are the sites of protein synthesis.

rRNA (Ribosomal RNA)

The structural component of ribosomes that acts as a substrate for protein synthesis.

tRNA (Transfer RNA)

An adaptor between nucleic acid sequences and protein products that brings specific amino acids to the ribosome.

Nucleoid

Also known as a genophore; the single, circular bacterial chromosome attached at one or many sites to the plasma membrane.

Transposons

Repetitive DNA sequences, ranging from $700$ to $40,000$ base pairs, that can move (transpose) from one location to another in the genome.

Semi-conservative replication

The synthesis of DNA where each parental strand serves as a template, resulting in daughter molecules containing one original and one new strand.

DNA polymerase

The enzyme responsible for adding nucleotides to the $3'$ end during DNA replication.

Transcription

The process of taking DNA code and converting it into RNA code, mediated by RNA polymerase.

Translation

The process of converting mRNA instructions into amino acid sequences and proteins, occurring at the ribosome with the help of tRNA.

Promoter

The region of DNA where RNA polymerase binds with the help of a sigma factor to initiate transcription.

Terminator

The specific site where RNA stops growing and the mRNA strand is released from the DNA.

Conjugation

The transfer of genetic material, usually a plasmid, from a donor to a recipient via physical contact between cells.

F+ cell

A bacterial cell possessing a fertility plasmid ($F$) capable of creating a sex pilus for conjugal transfer.

Hfr (high-frequency recombination) cell

A donor cell created when an $F$ factor integrates into the bacterial chromosomal DNA.

R factors

Plasmids containing genes that confer drug resistance, often carried on transposons.

Transduction

The phage-mediated transfer of host DNA sequences where a bacteriophage acts as the vector.

Bacteriophage

A parasitic virus of bacterial cells that utilizes the host's energy system and protein-synthesizing factors.

Specialized transduction

A process where only certain genes are transferred, such as those for diphtheria, erythrogenic, or Shiga toxins.

Transformation

The direct uptake and recombination of DNA fragments through the cell wall by a competent recipient bacterium.

Competent cell

A recipient cell able to alter its cell wall to allow large DNA molecules to enter for transformation.

Mutation

An induced or spontaneous heritable alteration of the DNA sequence that introduces variability into the gene.

Frameshift mutation

A mutation resulting from the insertion or deletion of one or two base pairs, which disrupts the phase of the triplet-encoded DNA message.

Missense mutation

A mutation that results in the substitution of one amino acid for another; it can sometimes be a silent mutation.

Nonsense mutation

A mutation that typically results in the production of inactive protein products.

Genotypic reversion

The restoration of function lost to mutation through restoration at the specific site of the DNA alteration.

Phenotypic reversion

The restoration of an activity lost to mutation without necessarily restoring the original genotype.