DNA and Bacterial Chromosomes

A circular molecule of DNA, typically a few million base pairs long, containing genes for various cellular functions.

The complete set of genetic material of an organism.

The region in a bacterial cell where the chromosome resides; it's not enclosed by a membrane.

The specific site on a chromosome where DNA replication begins.

Non-coding DNA segments located between genes on a chromosome.

The complete set of genetic material contained within the nucleus of a eukaryotic cell.

The process of duplicating the DNA molecule to produce two identical copies.

The process responsible for densely packing the chromosome into the cell.

Short segments (400-500 kbp) of the bacterial chromosome organized by nucleoid-associated proteins (NAPs).

Larger segments (800-1000 kbp) formed by adjacent microdomains in the bacterial chromosome. Organized by NAPs.

Proteins that organize and structure bacterial chromosomes into micro and macrodomains.

Twisting of the DNA double helix, leading to additional coils; creates tension affecting chromosome function

Underwinding of DNA; common in bacterial chromosomes; aids compaction, replication, and transcription.

Enzyme that introduces negative supercoils into DNA using energy from ATP.

Enzyme that relaxes negative supercoils in DNA by breaking and rejoining DNA strands.

DNA structures with different levels of supercoiling, but the same sequence.

Drugs that inhibit bacterial topoisomerases, often targeting DNA gyrase, used to treat bacterial infections.

Linear DNA molecules containing genes, origins of replication, centromeres, and telomeres.

DNA sequences found once or a few times in the genome; include protein-coding genes and non-coding DNA.

DNA sequences found hundreds to thousands of times, including rRNA genes and transposable elements.

DNA sequences found tens of thousands or millions of times in the genome, often in tandem arrays and in centromeres; function is often unknown.

Short DNA segments that can move to new locations within the genome.

The process of a DNA segment moving to a new location in the genome.

A type of transposon whose movement involves an RNA intermediate. They use reverse transcriptase to copy RNA back into DNA.

Reverse transcriptase is an enzyme that uses RNA as a template to synthesize a complementary DNA (cDNA) strand. This is essential for retrotransposons because their movement involves an RNA intermediate. The cDNA, along with the original RNA, form a double-stranded DNA molecule that can be integrated into the genome.

Long terminal repeats (LTRs) are DNA sequences that flank retrotransposons. They are involved in the integration of the transposon into the genome. Integrase recognizes LTRs.

An enzyme that cuts the target site on a chromosome and allows the insertion of a new DNA sequence, like a retrotransposon.

Transposable elements can influence the evolution of a species by introducing new genetic material or altering gene expression. They can cause mutations, leading to new traits or diseases.

Transposons can increase in number within the genome during DNA replication. As the DNA replicates, a transposon located near the replication fork can be copied and inserted into a new location on the daughter strand, resulting in two copies of the transposon.

Simple transposition involves the copying of the transposon. This copy can be inserted in a new location, leading to an increase in the number of transposons in the genome.

DNA segments that can move from one location to another within the genome.

A transposition pathway where the TE is cut out from its original site and inserted into a new location.

TEs that move via simple transposition.

A type of retrotransposon that is similar to retroviruses but lacks the ability to produce viral particles.

A type of retrotransposon that has less similarity to retroviruses and may encode reverse transcriptase and endonuclease.

A transposable element that contains all the necessary genes for transposition.

A transposable element that lacks a gene necessary for transposition and requires the presence of an autonomous element for movement.

An enzyme that catalyzes the movement of a TE to a new location.

The idea that transposable elements (TEs) exist primarily to perpetuate themselves, even at the expense of the host organism. They replicate and insert themselves into the genome for their own benefit.

A process where transposable elements (TEs) can insert exons into the coding region of other genes, potentially creating new gene functions or modifying existing ones.

A phenomenon in Drosophila flies where crosses between strains with and without P elements can lead to chromosomal abnormalities, sterility, and other genetic problems.

A possible consequence of transposable element (TE) excision, where the TE can excise incorrectly, leaving gaps or breaks in the DNA sequence.

A phenomenon where homologous recombination between TEs at different positions in the genome can lead to large-scale rearrangements of DNA segments.

A consequence of TE insertions, where the insertion can disrupt the function of a gene by interfering with its transcription or translation.

A potential outcome of TE insertions, where a TE can modify the expression of a gene by influencing its regulatory elements.