Week 11 Regulation of Gene Expression in Bacteria and their Viruses Flashcards
In what ways do the levels of gene transcription and RNA translation
vary?
Transcription is the process of copying a gene’s DNA sequence to make an RNA molecule and translation is the process in which proteins are synthesized after the process of transcription of DNA to RNA in the cell’s nucleus
How do cells sense environmental changes and trigger changes in
gene expression?
Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal’s genes are expressed, which ultimately affects the animal’s phenotype.
What are the molecular mechanisms of gene regulation in bacteria?
Bacteria have specific regulatory molecules that control whether a particular gene will be transcribed into mRNA. Often, these molecules act by binding to DNA near the gene and helping or blocking the transcription enzyme, RNA polymerase.
How is the expression of sets of genes coordinated?
Gene expression is a multi-step process starting from transcribing DNA through to the eventual production of proteins or RNA products. … Signal transduction pathways orchestrate such control and bring about wholesale changes in the gene expression profiles of cells that ultimately determine their phenotype.
Stages of Illumina DNA Sequencing
- DNA sequencing library construction - create fragments of DNA to be used
- DNA fragment binding to flow cell and cluster formation
- fragments are hybridized to the flow cell by the 3’ end - oligo acts as a primer for PCR amplification and clusters are formed
- reverse stranded are cleaved and washed off to leave the desired strand - Sequencing by synthesis
- use fluorescent nucleotides that will terminate the chain to show where each nuclotide is
Regulation of transcription relies on two types of protein-DNA interactions
One is the promoter region and the RNA polymerase which determine where transcription begins
Other interaction determines whether promoter driven transcription takes place
-Activators and repressors
Positive vs Negative regulation
Positive regulation: activator protein must bind to the target DNA site for transcription to begin
-presence
Negative regulation: repressor protein must be prevented from binding
-absence
What is the operator?
operator is a genetic sequence which allows proteins responsible for transcription to attach to the DNA sequence.
What are allosteric effectors and why is it important
Proteins must be able to exist in two states: one that binds to the target and one that does not
Allosteric effectors change the shape and makes the proteins functional or non functional - able to bind to the DNA binding domain
Allosteric site is where the effector binds on the protein
Does the activator or repressor protein control the lac operon?
The repressor protein
The lac operon is only transcribed in the presence of ___
lactose, it allosterically binds to the repressor protein preventing it from binding to the operator, allowing RNA polymerase to move from the promoter onwards and transcribe the operon
What is a constitutive mutant?
A mutant that makes product regardless
Induction and inducers
the process of turning a gene on and the protein in change of turning said gene on
- lactose is an inducer of lac operon
Cis-acting vs trans-acting
Cis-acting factors are mechanisms that affect gene expression only on the same chromosomal allele (usually DNA sequence P or O), while trans-factors act equally on both alleles (proteins such as inducers)
Operators are ___-acting and repressors are ___-acting
cis, trans
