CMU micro exam 2 – Flashcards
Unlock all answers in this set
Unlock answersquestion
| Most genes encode _____, and most proteins are _____. The expression of such a gene can be regulated by controlling the _____ of the enzyme or controlling the _____ of enzyme produced |
answer
proteins enzymes activity amount |
question
| Many metabolic reactions can be regulated through what method |
answer
| control of the activities of the enzymes that catalyze them. |
question
| feedback inhibition is where the |
answer
| final product of a biosynthetic pathway inhibits the first enzyme unique to that pathway. |
question
Covalent modification is a
Enzymes regulated in this way can be |
answer
regulatory mechanism for changing the activity of an enzyme.
reversibly modified |
question
| how can the amount of an enzyme in a cell be controlled |
answer
| by decreasing (repression) or increasing (induction) the amount of mRNA that encodes the enzyme. |
question
| in reduction negative control of transcription is used, the regulatory molecule is called a _____ and it functions by inhibiting _____ synthesis |
answer
repressor protein mRNA |
question
in induction Inducers may bind to |
answer
| repressors preventing them from binding to DNA thus activating transcription |
question
what happens in the case of the Lac operon, when lactose is present, |
answer
| some is converted to allolactose which binds to the repressor and activates transcription |
question
All three genes involved in the metabolism of lactose are located |
answer
| adjacent to each other on the bacterial chromosome |
question
what are the 3 genes involved in the metabolism of lactose and their control regions referred to |
answer
| the lac operon |
question
•The lac operon contains a short segment of DNA called |
answer
| the control region |
question
| Positive control of transcription is implemented by regulators called |
answer
| activator proteins |
question
| activator proteins bind to activator-binding sites on the _____ and_____ |
answer
| DNA and stimulate transcription |
question
| activator protein activity is modified by |
answer
| effectors. |
question
| how does positive control of enzyme induction work, |
answer
| the effector promotes the binding of the activator protein and thus stimulates transcription. |
question
| what is the function of Global control systems |
answer
| to regulate the expression of many genes simultaneously |
question
Catabolite repression is a ______, and it helps cells make the most efficient use of ______ sources. |
answer
global control system carbon |
question
| The lac operon is underwhat type of two controls |
answer
| catabolite repression as well as its own specific negative regulatory system |
question
Glucose is a better then lactose in what way , because of this what happens |
answer
provides a better carbon source
cells prefer to grow on glucose if both carbon sources are available |
question
Lactose digestion steps |
answer
The lactose repressor is always synthesized = lactose metabolizing genes are normally turned off •When lactose is present it is converted to allolactose which acts as an inducer for lactose metabolizing enzymes by binding to the repressor = lactose genes are turned on •When glucose is also present cAMP is low and the CAP (catabolic activator protein) protein cannot bind the promoter = no transcription of lac genes |
question
| what is the stringent response and how is it triggered |
answer
| is a global control mechanism triggered by amino acid starvation. |
question
| The alarmones guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) are produced by _____, a protein that monitors_____ activity. |
answer
RelA ribosome |
question
•Alarmones inhibit _____ and _____synthesis |
answer
tRNA rRNA |
question
what is the function of the stringent response |
answer
| It achieves balance within the cell between protein production and protein requirements. |
question
| When more than one operon is under the control of a single regulatory protein, these operons are collectively called |
answer
| regulons |
question
| what are some other types of global signals |
answer
| cold and heat shock proteins that function to help the cell overcome temperature stress. |
question
| what is the function of Quorum sensing |
answer
| allows cells to survey their environment for cells of their own kind |
question
Gram negative bacteria communicate using _____ (AHL) as ________ |
answer
| acyl-homoserine lactone autoinducers |
question
| Gram positive bacteria produce small peptides called ______. |
answer
| autoinducer peptides |
question
| ________ uses a two-component system consisting of auto inducer 1 (AI-1) and autoinducer 2 (AI-2) |
answer
| Vibrio harveyi |
question
| what pathogenic bacteria use quorum sensing and what does this do for the cell |
answer
Pseudomonasto determine when sufficient numbers are present in the population to overcome host defenses and cause disease |
question
| what do Pseudomonas do to resist antibiotics |
answer
| form a biofilm |
question
what is Attenuation |
answer
| is a mechanism whereby gene expression (typically at the level of transcription) is controlled after initiation of RNA synthesis. |
question
Attenuation mechanisms involve a coupling of transcription and translation and can therefore occur only in _________. |
answer
| prokaryotes. |
