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62 Cards in this Set
- Front
- Back
Promoter
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where RNA polymerase binds upstream of coding region of gene to initiate transcription
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coding region
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where translation starts (AUG)
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one
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sometimes there's is only how many genes associated with a promoter?
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operon
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- a set of genes transcribed from the same promoter
- only found in prokaryotes |
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constitutively
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~60-80% of genes are what expressed ?
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regulated
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genes that are not constitutively expressed are what in response to changes in the environment
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repression and activation
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transcription is regulated in what two ways?
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repressor
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inhibits transcription, often by blocking RNA polymerase from binding to the promoter
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operator
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the region the repressor binds to
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repressor
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with this, repressor binds operator and blocks RNA polymerase from initiating transcription
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induction
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turns on transcription of genes being repressed
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inducer
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- binds to the repressor, causing it to fall off operator and allow genes to be expressed
- often a signal that substrate of enzymes is present |
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promoter
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positive regulators help recruit RNA polymerase to what?
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activator
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- without this, RNA polymerase has trouble binding to weak promoter
- causing transcription to not occur |
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activators
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- help recruit RNA polymerase to the promoter activating transcription
-help make enzymes only when their substrate is present |
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transcription
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with activator, activator helps RNA P bind and initiate what?
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three proteins
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how many proteins do the lac operon genes encode that use the sugar lactose as a carbon and energy source ?
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glucose
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- the best source of energy
- feeds straight into glycolysis - reflected better in growth rate - if cells had a choice it would choose to use this first and then make proteins use lactose |
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no lactose is present
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the cell doesn't want to waste energy making the lactose enzymes/transporter, this happens when?
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lactose is present
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-cells sense it
- allolactose is a form of it and an inducer |
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allosteric inhibition
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binds to Lacl and blocks it from binding to the operator
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lactose inducer
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- with this, repressor is not bound
- however, RNA polymerase also needs CAP (activator) to help it bind and initiate transcription |
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CAP activator is inactive
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- high glucose = low cAMP = ...
- RNA polymerase still can't initiate lac transcription - cell uses glucose instead of lactose |
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CAP activator is active
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- low glucose = high cAMP = ...
- CAP helps RNA polymerase bind and start lac transcription - cell uses lactose |
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small regulatory (sRNA)
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- one type of cell RNA
- small - unlike mRNA, most do not encode information to make proteins - huge role in cell survival, health, and disease - recent significance |
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negative
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what type of regulating sRNA often block translation by inhibiting ribosome binding to the mRNA
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positive
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what type of regulating sRNA often enhance translation by stabilizing mRNA or helping the ribosome bind
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mutant
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organism that has the mutation
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wild-type
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- the 'normal' strain of a bacterium isolated from nature
- doesn't have a given mutation |
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genotype
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- the genetic (DNA) make-up of an organism
- the information that codes for all its particular characteristics |
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phenotype
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- manifestation of an organisms genotype
- actual, expressed properties, functions, behaviors |
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1) make enzyme work faster/more efficiently
2) antibiotic resistance |
what are the beneficial parts of mutations?
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lose function of important protein
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what is a harmful effect of mutations
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point mutation
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- type of mutation
- a single nucleotide base pair in the DNA is replaced with a different one - a.k.a. base pair substitution - often due to substitution errors during DNA replication |
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frameshift mutation
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- type of mutation
- insertion or deletion of one or more nucleotides in the DNA - completely changes an amino acid sequence = BAD |
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silent mutation
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- type of point mutation
-substitution results in codon that still encodes for the same amino acid - not affect phenotype |
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silent mutation
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- due to degeneracy of genetic code
- e.g. UAU ➡UAC - both encode for tyrosine so protein is unaffected |
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missense mutation
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- type of point mutation
- substitution results in codon that encodes a different amino acid in the protein |
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nonsense mutation
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- type of point mutation
- substitution results in change to stop codon - often result in truncated proteins = missing amino acids - usually protein is nonfunctional |
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spontaneous mutations
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- one way mutations occur
- random, rare errors made by DNA polymerase during DNA replication |
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mutagens
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- one way mutations occur
- chemicals or radiation induce mutating to occur - increase rate at which mutations happen vs spontaneous |
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spontaneous and mutagen
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mutations are random. how do they happen?
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chemical mutagen
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- any chemical that can react with DNA to change its sequence
- altering base - analog substitution for/look like base |
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physical mutagen
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- result in lots of reactive ions and free radicals
- oxidize bases, resulting in errors in DNA replication/repair - e.g. x-rays and gamma rays |
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form new combinations of genes on the chromosome
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the exchange of genes/DNA fragments between two DNA molecules, it can do what?
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chromosomal DNA
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when foreign DNA is transfered into a cell, it can sometimes recombine with what of a similar sequence?
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recombination
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- expression of a different form/version of a given protein via what can allow bacteria to evade the immune system
- e.g. different forms of Salmonella and Neisseria |
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vertical gene transfer
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genes are passed from an organism to its offspring
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horizontal gene transfer
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- genes are passed to other microbes of the same generation
- e.g. donor cell gives some of its DNA to a recipient |
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transformation
transduction conjugation |
what are the three main ways DNA can be transferred into bacterial cell
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transformation
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- DNA enters cell by its lonesome
- genes are transferred via free DNA in solution - source: usually DNA from dead cells |
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dead capsule
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DNA from what + cells give non-capsulated cells the ability to form capsules and cause disease
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transduction
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- bacterial DNA is accidentally packaged into bacteriophage capsid then transferred/introduced into recipient cell
- two types: generalized and specialized |
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generalized transduction
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- type of transduction
- any bacterial genes are equally likely to be packaged into phage capsid |
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specialized transduction
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- type of transduction
- only certain bacterial genes are transferred - e.g. C. diphtheriae toxin |
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conjugation
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- bacterial DNA is transferred directly from cell to cell
- occurs via plasmid - requires cell-to-cell contact - requires opposite mating types: donor (has plasmid) and recipient (does not) |
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e.coli
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name an example of cojugation
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resistance (R) factors
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plasmids that carry genes that encode for antibiotic resistance
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virulence factor plasmids
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carry genes that aid in pathogens ability to cause disease
- toxins that harm host - adhesions that allow pathogen to attach to host cells |
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transposons
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- small, mobile fragments of DNA that can move from one region of a DNA molecule to another
- able to insert or transpose directly into the chromosome |
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biotechnology
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- the use of microbes, cells, or cell components to make a product
- e.g. e. coli |
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Biotechnology
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- used to produce genes
- plants and animals can be altered - used for drug discovery and production, vaccine development, diagnostics assay, etc. |