Bacterial vs Eukaryotic Genomes

Both require DNA polymerase, a template DNA strand, and nucleotides. Both processes synthesize DNA in the 5' to 3' direction.

Bacterial genomes are typically circular, while eukaryotic genomes are linear.

Plasmids are extrachromosomal DNA molecules that can carry genes for traits like antibiotic resistance or virulence factors.

<p>Heat denaturation separates the double-stranded DNA template into single strands, allowing primers to bind to the template.</p> Signup and view all the answers

<p>An operon is a group of genes transcribed together as a single unit in bacteria. In contrast, eukaryotic genes are typically individually regulated.</p> Signup and view all the answers

<p>Primers are short, single-stranded DNA sequences that are complementary to specific regions on the template DNA. They provide a starting point for DNA polymerase to begin replicating the template.</p> Signup and view all the answers

<p>Free-living bacteria tend to have the largest genomes because they need to encode a wider variety of genes for survival in diverse environments.</p> Signup and view all the answers

<p>Cis-acting elements are DNA sequences located on the same molecule as the gene they regulate, while trans-acting factors are proteins or RNAs that bind to these elements to influence gene expression.</p> Signup and view all the answers

<p>The TATA box is a cis-acting element located approximately 30 base pairs upstream of the transcription start site. It serves as a binding site for the TATA-binding protein (TBP), which helps to recruit other transcription factors and RNA polymerase to the promoter region.</p> Signup and view all the answers

<p>Obligate pathogens or symbionts often have the smallest genomes due to gene loss over time, as they rely heavily on their host for resources.</p> Signup and view all the answers

<p>DNA polymerase adds new nucleotides to the 3' end of an existing DNA strand.</p> Signup and view all the answers

<p>In bacteria, transcription and translation occur simultaneously because there is no nuclear membrane separating the two processes. Ribosomes can bind to the mRNA and initiate translation while it is still being transcribed.</p> Signup and view all the answers

<p>DNA polymerase utilizes a free 3' hydroxyl group on the existing strand to form a phosphodiester bond with the incoming nucleotide, enabling the addition of new nucleotides.</p> Signup and view all the answers

<p>In eukaryotes, transcription occurs in the nucleus, while translation occurs in the cytoplasm. The mRNA must undergo processing and be exported from the nucleus before translation can occur.</p> Signup and view all the answers

<p>The sigma factor is a subunit of bacterial RNA polymerase that recognizes and binds to specific DNA sequences called promoters, initiating transcription.</p> Signup and view all the answers

<p>DNA synthesis proceeds in the 5' to 3' direction.</p> Signup and view all the answers

<p>The sigma factor helps RNA polymerase recognize and bind to the promoter region of DNA, facilitating the initiation of transcription.</p> Signup and view all the answers

<p>Bacteria employ alternative sigma factors, such as σ70, σ32, and σ54, to respond to various environmental cues. Each sigma factor recognizes a specific set of promoters, allowing for selective expression of genes related to specific functions like housekeeping, heat shock response, or nitrogen metabolism.</p> Signup and view all the answers

<p>Promoter strength refers to the efficiency with which RNA polymerase binds to a promoter and initiates transcription. Strong promoters have sequences closely matching the consensus sequences, leading to higher transcription rates. Weaker promoters with deviations from the consensus sequence result in lower transcription levels.</p> Signup and view all the answers

<p>Polycistronic mRNAs are single mRNA molecules that encode multiple proteins. Bacteria organize functionally related genes into operons, which are transcribed as a single polycistronic mRNA. This allows for coordinated regulation of gene expression and efficient protein synthesis.</p> Signup and view all the answers

<p>The genetic code is considered degenerate because multiple codons can encode the same amino acid. This redundancy provides flexibility and reduces the effects of mutations. If a mutation changes a codon, there is a chance it will still encode the same amino acid, preventing a change in the protein sequence.</p> Signup and view all the answers

<p>The Shine-Dalgarno sequence is a ribosome-binding site located upstream of the start codon in bacterial mRNA. It plays a crucial role in initiating translation by providing a binding site for the small ribosomal subunit, ensuring that the ribosome aligns with the correct start codon.</p> Signup and view all the answers

<p>The Shine-Dalgarno sequence facilitates efficient translation by acting as a binding site for the small ribosomal subunit. This interaction ensures that the ribosome is positioned correctly on the mRNA, allowing it to initiate translation at the appropriate start codon.</p> Signup and view all the answers

<p>Grouping related genes into operons and transcribing them as polycistronic mRNAs offers several advantages for bacteria, including coordinated regulation of gene expression, efficient protein synthesis, and optimal resource utilization. This organization allows bacteria to respond to environmental changes and manage their metabolic pathways effectively.</p> Signup and view all the answers

<p>The Shine-Dalgarno sequence helps align the ribosome with the start codon (AUG) during translation initiation.</p> Signup and view all the answers

<p>tmRNA rescues stalled ribosomes by inserting a peptide tag into the incomplete protein, leading to its degradation. The process involves tmRNA binding to the A-site of the ribosome, adding a peptide tag to the incomplete protein, and directing it for degradation by proteases.</p> Signup and view all the answers

<p>The three postulates are: 1) the gene must be associated with pathogenic bacteria, 2) inactivating the gene should reduce virulence, and 3) restoring the gene should restore virulence. These postulates aid in identifying specific virulence genes and understanding their role in pathogenicity.</p> Signup and view all the answers

<p>The Shine-Dalgarno sequence helps position the ribosome correctly on the mRNA by base pairing with a complementary sequence in the 16S rRNA. This alignment ensures that the start codon (AUG) is positioned in the ribosome's P-site, allowing for the initiation of protein synthesis.</p> Signup and view all the answers

<p>Trans-translation addresses the problem of stalled ribosomes caused by the absence of a stop codon in the mRNA.</p> Signup and view all the answers

<p>Identifying and studying virulence genes is crucial for understanding how bacteria cause disease and enables the development of strategies for preventing and treating infections.</p> Signup and view all the answers

<p>Trans-translation involves three main steps: 1) Binding of tmRNA to the A-site of the ribosome, 2) Addition of a peptide tag to the incomplete protein by tmRNA, and 3) Direction of the tagged protein for degradation by proteases.</p> Signup and view all the answers

<p>The peptide tag acts as a signal for the degradation of the incomplete protein.</p> Signup and view all the answers

Both require DNA polymerase, template DNA, and nucleotides; both are 5’ to 3’ synthesis.

Utilizes DNA polymerase III for replication inside cells.

Uses Taq polymerase for amplification in a test tube.

Requires primase and an RNA primer to start replication.

Uses pre-designed DNA primers to start the amplification process.

Regulatory DNA sequences on the same DNA molecule as the gene they control.

Proteins or RNAs that regulate gene expression from a different molecule.

In bacteria, these processes occur simultaneously in the cytoplasm without a nucleus.

Bacterial genomes are smaller, circular, and lack introns and operons.

Eukaryotic genomes are larger, linear, have introns, and use individual regulation.

Plasmids are extra DNA in bacteria for antibiotic resistance or virulence.

Free-living bacteria have the largest genomes, while obligate pathogens have the smallest.

Obligate pathogens lose genes over time, relying on hosts for nutrients.

DNA polymerases add nucleotides to the 3’ end of a DNA strand.

DNA synthesis occurs in the 5’ to 3’ direction.

Bacterial chromosomes compact using histone-like proteins; eukaryotes wrap DNA around histones.

A protein that helps RNA polymerase bind to promoters during transcription.

Different sigma factors that help bacteria regulate gene expression based on conditions.

Refers to the efficiency of RNA polymerase binding and transcription initiation.

A type of mRNA that encodes multiple proteins from one transcript.

Clusters of functionally related genes transcribed together in bacteria.

Multiple codons can encode the same amino acid, allowing flexibility in protein synthesis.

A ribosome-binding site in bacterial mRNA crucial for initiating translation.

A sequence that represents the most common nucleotides at a specific location in promoters.

It pairs with the 16S rRNA of the 30S ribosomal subunit, ensuring correct ribosome alignment at the start codon.

Transfer-messenger RNA that rescues stalled ribosomes when mRNA lacks a stop codon by adding a peptide tag.

A process where tmRNA helps ribosomes resume translation by providing a tag for degradation of incomplete proteins.

A set of criteria by Falkow to establish a link between specific genes and their role in pathogenicity.

The gene must be associated with pathogenic bacteria to suggest a role in virulence.

Inactivation of the gene should result in decreased virulence of the bacteria.

Restoring the gene’s function must restore the virulence of the bacteria.