General Microbiology Chapters 8 and 9
Terms
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- What is an activator protein?
- a reulatory protein that binds to specific sites on DNA and stimulates transcription; involved in positive control.
- Allosteric enzyme
- An enzyme that contains two binding sies, the active site (where the substrate binds) and the allosteric site (where an effector molecule binds)
- Attenuation
- A control system when the control occurs after initiaion of transcription but before its completion.
- Feedback inhibition
- a decrease in the activity of the first enzyme of a pathway caused by the final product of the pathway.
- Gene expression
- transcription and/or translation of genes.
- Heat shock proteins
- a series of proteins induced by a sudden upshift in temperature or certain other stress factors that function to refold partially denatured proteins.
- Induction
- production of an nzyme only when its substrate is present
- Kinase
- an enzyme that adds a phosphoryl group to a compound
- Negative Control
- a mechanism for regulation gene expression in which a repressor protein functions to prevent transcription of a gene or genes
- Operon
- One or more genes transcribed into a single RNA and under the control of a single regulatory site
- Positive Control
- A mechanism for regulaing gene expression in which an activator protein functions to promote transcription of a gene or genes
- Quorom sensing
- A regulatory system in an organism that requires a certain density of cells of the same species be present before the regulatory events occur
- Repression
- Prevention of an enzyme's synthesis when the product of its reaction is present in excess
- Repressor protein
- a regulatory prtein that binds to specific sites on DNA and blocks transcription; involved in negative control
- Response regulator protein
- one of the members of a two-component system;a regulatory protein that is phosphorylated by a sensor kinase protein
- Riboswitch
- a messenger RNA that can bind a specific small molecule near its 5' end that alters its secondary structure and makes it unavailable for translation
- Sensor Kinase protein
- one of the members of a two-component system; a membrane integrated protein that phosphorylates itself in response to an external signal and then transfers the phosphoryl group to a response regulator protein
- Stringent Response
- a global regulatory control that is activated by amino acid starvation
- Two-component Regulatory System
- A regulatory system contain two proteins: a sensor kinase and a response regulator
- Bacteriophage
- a virus that infect prokaryotic cells
- Early protein
- A protein synthesized soon after virus infection
- Late protein
- a protein synthesized toward the end of virus infection
- lysogen
- a bacterium containing a prophage
- Lysogenic pathway
- a series of steps that, after virus infection, lead to a state (lysogeny) where the viral genome is replicated as a prophage along with that of the host.
- Lytic pathway
- a series of steps after virus infection that leads to virus replication and the destruction (lysis) of the host cell
- Minus (negative)-strand virus
- a virus with an RNA genome in which the RNA strand has the oppostie sense of (s complementary to) the mRNA of the virus
- Nucleocapsid
- the complex of nucleic acid and proteins of a virus
- Oncogene
- a gene whose expression cases formation of a tumor
- Plaque
- a zone of lyis or cell inhibition caused by virus infection of a lawn of sensitive cells
- Plus (positive)-strand virus
- a virus with an RNA or DNA genome in which the genome has the same complementarity as the mRNA of the virus
- Prion
- an infectious protein whose extracellular form contains no nucleic acid
- Provirus
- the genome of temperate virus when it is prelicatin with, and usually integrated into the host chromosome
- Retrovirus
- a virus whose RNA genome has a DNA intermediate as part of its replication cycle
- Reverse transcription
- the process of copying informationi found in RNA into DNA by the enzyme reverse transcriptase
- Temperate virus
- a virus whose genome is able to replicate along with that of its host and not cause cell death in a state called lysogeny
- Transformation
- in eukaryotes, a pocess by which a normal cell becomes a cancer cell
- Virion
- the complete virus particle; the nucleic acid surroundd b a protein coat in some cases other material
- Virulent virus
- a virus that lyses or kills the host cell after infection; a nontemperate virus
- Virus
- a genetic element containing either RNA or DNA that replicates in cells but is characterized by having an extracellular state.
- Viroid
- small, circular, single-stranded rna that causes various plant diseases.
- Various phases of virus replication
-
1. attachement
2. penetration
3. Synthesis
4. Assembly
5. Release - Attachment
- The virion attaches to a susceptible host cell
- Synthesis
- occurs for the nucleic acid and protein by cell metabolism as redirected by the virus early in the infection. late in the infection, structural proteins that are subunits of the virus capsid are synthesized, 3rd step
- Assembly
- The capsomers assemble (and membrane components in enveloped viruses) and nucleic acids are packaged into new virions, 4th step
- Release
- Mature virions are released from the cell, 5th step
- Phosphatase
- an enzyme that removes the phosphoryl group from the response regulator protein at a constant rate
- Examples of 2-component Regulatory Systems
-
Assimilation in E. coli
Nitrogen fixation in Klebsiella and Rhizobium
Sporulation in Bacillus - Nar Regulatory System
- controls a set of anaerobically induced genes and contains two different sensor kinases and two different resonse regulators
- Steps in Regulation of Chemotaxis and Flagellar Rotation
-
1.Response to Signal
2. Controlling Flagellar Rotation
3. Adaption - Response to Signal
-
Step One of Flagellar Rot.
Methyl-accepting chemotaxis proteins bind attractants or repellents directly - Controlling Flagellar Rotation
-
CheY-P causes the flagella to rotate clockwise
CheZ dephosphorylates CheY-P
Repellents increase the level of CheY-P and lead to tumbling, whereas attractants lead to a lower level of cheY-P and smooth swimming - Adaption
-
Step 3 in Flagellar Rotatioin
the feedback loop necessary to reset the system. - Virus Size
- 0.02 micometers- 0.3 micrometers
- Capsid
- Protein Shell composed of a number of individual protein molecules called structural sbunits, which are arranged in precise and highly repetitive pattern around the nucleic acid
- Capsomer
- The smallest morphological unit that can be seen with the electron microscope
- Icosahedron
-
a symmetric structure containing 20 faces and is roughly spherical in shape.
The most efficient arrangement of subunits in a closed shell - End point dilution
- The dilution at which, 1/2 the organisms are affected
- Virus infectious Unit
- the smallest unit that causes a detectable effect when added to a susceptible host
- Latent period
- the eclips and maturation periods of Virus replication; newly synthesized virions do not appear outside the cell
- Burst Size
- the number of virions released during release; from a few to a few thousand
- Ambiviruses
- contain a single stranded RNA genome, half of which are in the plus orientation and half in the minus configuration
- circularly permuted molecules
- appear to have been linearized by opening a circle but at different locations