DNA and Bacterial Chromosomes

Chromosomes.

The bacterial chromosome is usually a single circular molecule, while eukaryotic chromosomes are linear and contain multiple sets.

Intergenic regions may contribute to DNA folding, gene regulation, and genetic recombination.

<p>It serves as the initiation site for DNA replication.</p> Signup and view all the answers

<p>Bacterial DNA needs to be compacted about 1000-fold to fit within the cellular environment.</p> Signup and view all the answers

<p>A typical bacterial chromosome is a few million base pairs long and contains a few thousand different genes.</p> Signup and view all the answers

<p>The nucleoid.</p> Signup and view all the answers

<p>The main function is to store information required for producing an organism.</p> Signup and view all the answers

<p>Unique or non-repetitive sequences are those found once or a few times in the genome and comprise roughly 41% of the human genome.</p> Signup and view all the answers

<p>Moderately repetitive sequences are found a few hundred to a few thousand times and include genes for rRNA and transposable elements.</p> Signup and view all the answers

<p>Highly repetitive sequences are found tens of thousands to millions of times, and their function is not well understood.</p> Signup and view all the answers

<p>Transposition is the process by which a DNA segment is inserted into a new location within the genome, potentially affecting gene function.</p> Signup and view all the answers

<p>Transposable elements are segments of DNA that can move within the genome and can influence gene function and genome organization.</p> Signup and view all the answers

<p>Transposition can occur during replication, where one transposon can be copied and lead to increased copies in the genome.</p> Signup and view all the answers

<p>The two key enzymes are reverse transcriptase and integrase.</p> Signup and view all the answers

<p>Retroelements use an RNA intermediate for transposition, while regular transposons do not.</p> Signup and view all the answers

<p>IS1 is a transposon commonly found in multiple copies in E. coli.</p> Signup and view all the answers

<p>The Alu retrotransposon is approximately 300 bp in length.</p> Signup and view all the answers

<p>Transposable elements can rapidly enter and proliferate within genomes, leading to genetic diversity.</p> Signup and view all the answers

<p>The transposon is called P elements and has an approximate length of 500-3000 bp.</p> Signup and view all the answers

<p>L1 is a retrotransposon found in about 500,000 copies in the human genome.</p> Signup and view all the answers

<p>NAPs help form micro and macrodomains by bending DNA or acting as bridges between DNA regions.</p> Signup and view all the answers

<p>Negative supercoiling helps in the compaction of the chromosome and creates tension that releases during DNA strand separation, enhancing replication and transcription.</p> Signup and view all the answers

<p>DNA gyrase creates negative supercoils using energy from ATP and can also relax positive supercoils.</p> Signup and view all the answers

<p>They are crucial for bacterial survival, and inhibiting them can effectively treat bacterial diseases.</p> Signup and view all the answers

<p>Telomeres are regions at the ends of chromosomes that prevent translocations and maintain chromosome length.</p> Signup and view all the answers

<p>Prokaryotic chromosomes are typically circular and located in the nucleoid, while eukaryotic chromosomes are linear and located in the nucleus.</p> Signup and view all the answers

<p>Less complex eukaryotes typically have smaller genes with few introns, while more complex eukaryotes have longer genes with many introns.</p> Signup and view all the answers

<p>Genome sizes vary significantly among species and much of this variability is due to repetitive DNA sequences rather than the number of protein-coding genes.</p> Signup and view all the answers

<p>Topoisomers are DNA structures that differ in supercoiling, resulting from changes in twisting forces.</p> Signup and view all the answers

<p>Centromeres are the constricted regions of chromosomes responsible for segregation, while kinetochores are proteins that link centromeres to the spindle apparatus.</p> Signup and view all the answers

<p>Barbara McClintock identified transposable elements in corn.</p> Signup and view all the answers

<p>The two basic pathways are simple transposition and retrotransposition.</p> Signup and view all the answers

<p>Simple transposons move by a 'cut and paste' mechanism, while retrotransposons move through an RNA intermediate followed by reverse transcription.</p> Signup and view all the answers

<p>Transposase catalyzes the excision and reinsertion of transposable elements at new locations.</p> Signup and view all the answers

<p>Autonomous elements contain all necessary information for transposition, while nonautonomous elements lack some necessary genes.</p> Signup and view all the answers

<p>The two categories are LTR retrotransposons and non-LTR retrotransposons.</p> Signup and view all the answers

<p>An example of a non-LTR retrotransposon in humans is Alu.</p> Signup and view all the answers

<p>Simple transposons typically have flanking direct repeats, inverted repeats, and a transposase gene.</p> Signup and view all the answers

<p>A transposase is an enzyme that facilitates the movement of transposable elements, while Ds is a nonautonomous transposable element that lacks a functional transposase-encoding gene.</p> Signup and view all the answers

<p>Xenopus laevis (the frog) has the highest percentage at 77%.</p> Signup and view all the answers

<p>The selfish DNA hypothesis suggests that transposable elements exist simply because they can proliferate within a host without causing significant harm.</p> Signup and view all the answers

<p>Transposable elements can insert exons into the coding region of other genes, thereby creating new gene functions through a process known as exon shuffling.</p> Signup and view all the answers

<p>Uncontrolled transposon activity can lead to chromosomal abnormalities and sterility, such as in hybrid dysgenesis observed in Drosophila.</p> Signup and view all the answers

<p>Escherichia coli, which has only 0.3% of its genome composed of transposable elements.</p> Signup and view all the answers

<p>Transposon activity can be stimulated by radiation, mutagens, and hormones.</p> Signup and view all the answers

<p>Transposons can alter gene regulation by transposing next to regulatory sequences, affecting how genes are expressed.</p> Signup and view all the answers

<p>Hybrid dysgenesis is a phenomenon in Drosophila where the introduction of P elements to a strain lacking them leads to sterility and developmental issues.</p> Signup and view all the answers

<p>Transposable elements in bacteria may carry antibiotic-resistance genes, providing a survival advantage.</p> Signup and view all the answers