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Microbiology Quiz - Bacterial Genetics
Terms in this set (62)
Made of contiguous packets of information, called genes
tRNA, mRNA, rRNA
A structural gene produces a _________.
DNA control sequence
Regulates Expression of a structural gene, does NOT encode an RNA or protein, includes promoters and binding sites for regulatory proteins
Anti-parallel strands of nucleotides that are held together by H-bonded side chains.
Give the overall structure of DNA that is the same across all domains.
Most bacteria have __________, ______ chromosomes.
For PROKARYOTES, but not eukaryotes, the number of kb in a gene is a testament to the __________ of the genomes
Bacterial genomes have a lot less ___________ DNA than eukaryotic genomes.
They delete superfluous genes in order to replicate faster.
Give an example of how bacteria undergo reductive evolution.
Transformation, transduction, conjugation
Name the three types of horizontal gene transfer.
The introduction of extracellular DNA directly into an organism
In transformation, the donor cell is ________
A bacterium that has the cellular mechanics to uptake DNA is known as _________
In transformation, the DNA enters the cell using ______
ssDNA binding protein and RecA
One strand is uptaken, and the other is degraded and reused. The DNA that makes it through the more and the DNA translocase is bound to the ____________ and __________
In transformation, the DNA is incorporated into the genome by __________________
it is degraded
What happens to the recipient strand that is replaced by the extracellular DNA brought into the cell?
The transfer of DNA from cell to cell via direct contact/sex pilus formation
High Frequency of Recombination
What does HFR stand for?
The F plasmid integrates with chromosome
How does a cell become an Hfr cell?
Only some of the F plasmid enters the recipient, along with some of the donor chromosome. The rest of the plasmid doesn't transfer through, thus NOT creating an F+ cell.
In nature, what gets transferred when an Hfr cell transfers part of its chromosome?
A plasmid that excises itself from an Hfr chromosome inaccurately, bringing some of the host cell DNA into the plasmid with it.
phages accidentally take one cell's DNA and place it into another's
In some life cycles, the bacterial chromosome is segmented by the phage. Sometimes, parts of the bacterial genome is packed into the transducing phage capsid, allowing it to carry bacterial DNA instead of phage DNA
How does transduction occur?
mRNA that codes for only one gene is called
mRNA that codes for more than one gene is called
mRNA is coded for by the ___________ strand of DNA
Where does RNA polymerase bound on the template strand?
Ribosome binding site (RBS)
Translation begins at the ______________
(T/F) Each protein in an operon has its own RBS
5' to 3'
mRNA is built from ___ to ___
3' to 5'
RNA polymerase moves along the template strand from ___ to ___
Process in which sigma factors recruit RNA polymerase to the promoter
Process in which ribonucleotides are added onto the protein
making the channel through which the DNA strand passes
The beta subunits of RNA polymerase are responsible for _________________________
scaffolding the RNA polymerase protein
The alpha subunits of RNA polymerase are responsible for ______________
Recognizing the promoter sequence.
The sigma factor of the RNA polymerase is responsible for __________
being a stabilizer in poor conditions
The omega subunit of the RNA polymerase is responsible for ______
directs the RNA polymerase to the promoter
The sigma factor binds to the RNA polymerase, and then ___________________
The sigma 70 sigma factor in E coli is known as a ________________________ sigma
-10 & -35
2 regions of nucleotides are necessary for the recognition of the promoter by sigma. These are usually located at _____ and ______
sigma factor _______________ after directing the RNA polymerase to the promoter
Rho and RNA pol are moving down the strand at the same time. Rho moves slower than RNA pol, so it needs to catch up when RNA pol reaches a pause site. When rho finally catches up and makes contact w RNA pol, termination occurs.
Describe Rho-dependent termination
The end of the gene is rich in G and C nucleotides. When this is transcribed, it forms a hairpin loop from bp with each other. This hairpin loop attaches to a protein called NusA. When NusA binds to RNA polymerase, it causes RNAP to pause over an area of the DNA-RNA hybrid that is rich in A and U base pairs. The A and U base pairs are too weakly bonded to each other to keep the strands together, so the RNA falls off and the transcription is terminated.
Describe rho-independent termination
Svedberg; sedimentation rates in a centrifuge
The S values (ex. 70S) are indicative of the _________________ unit that measures _______________
The difference between prokaryotic and eukaryotic ribosomes is important for understanding why some antibiotics are ______________________
it is responsible for linking on amino acids to peptides that are built during translation
What is the purpose of the tRNA?
1. Shape of the tRNA (specific to bind to certain AA's)
2. Anticodon (each specific for a codon)
3. Attachment site
Which aspects of tRNA describe how it can link specific amino acids?
The Shine-Delgarno sequence of mRNA allows a certain base pairing region of the rRNA to bind to it. This base pairing places the start codon of the mRNA into the exact position where the tRNA can bind to the start codon and begin translation
Explain the operation of the Shine-Delgarno sequence
5' to 3' ; N to C
In translation, ribosomes read the mRNA from the ___ to ___ direction; and the protein is built from the ___ terminus to the ___ terminus
Degradation by nucleases
What does coupling the transcription and translation protect against in bacteria?
Activators and Repressors regulate the process of __________________________________
Binds to DNA, assists binding of RNA polymerase
activator binding site
Sequence of DNA that contacts the activator
Sequence of DNA that binds to a repressor
Small regulatory proteins that bind to activators and repressors
inducers/coactivators, and corepressers
What are the two types of effectors?
When an activator is present, the system is under _______________ control.
When a repressor is present, the system is under _______________ control
inducer; activators; repressors
Inducible operons are those that have an ________________ that can enable ________________ or disable _________________
Inducible operons always __________________ transcription, while repressible operons always __________________ transcription
Corepressors can ________________ activators or ________________ repressors
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