Biology 2100 Final Exam Study Guide 2022 with complete
solution
operon
a stretch of DNA consisting of an operator, a promoter, and genes for a related set of
proteins, usually making up an entire metabolic pathway
genes of an operon
arranged sequentially after the promoter
promoter
a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start
transcribing RNA at the appropriate place
regulatory gene
codes for a protein, such as a repressor, that controls the transcription of another gene
or group of genes
operator
regulatory proteins bind to the operator to control expression of the operon
repressor
a protein that inhibits gene transcription. In prokaryotes, the repressor binds to the
operator and blocks DNA polymerase from attaching to the promoter, which prevents
transcription
inducer
a specific small molecule that binds to a bacterial regulatory protein and changes its
shape so it can't bind to an operator, thus switching an operon on
replica plating
a way of screening a large number of mutants very efficiently
start with wild type organism, mutate it, then replica plating
lac Y
protein which allows bacteria to pick up lactose
permease-minus
mutant of bacteria without lac Y
lac Z
enzyme that cleaves the disaccharide of glucose into monosaccharides for energy
(mutant doesn't have this enzyme); gene for b-galactosidase
constitutive mutant
expressed lacZ and lacY even in the absence of lactose
negative control
inhibition of genes; regulation of trp and lac operons are this because operons are
switched off
polycistionic mRNA
codes for multiple proteins; has multiple start codons (as many start codons as there
are protein products)
southern blot
helps answer "is a particular DNA sequence present in this sample?"
southern blot mechanism
, restriction digest of DNA ---> electrophoresis ---> transfer of DNA from gel to membrane
surface (blotting) ---> probing with radioactive oligonucleotide ---> autoradiography
antisense RNA
complementary to mRNA
experiment with antisense RNA
sense RNA --> parent --> no effect in offspring
anti-sense RNA --> parent --> no effect in offspring
double-stranded RNA --> parent --> "twitching" offspring
catalytic
small number of double-stranded RNA eliminates all target RNA in the cells
rna induced silencing complex
there is point where one of the strands of double-stranded RNA gets kicked out of the
cell so only one strand is left
if bases of RNA are completely complementary....
the protein is degraded. Otherwise, the transaction is blocked
Sanger method
making DNA in the process: need polymerase, primers, template nntp's ---> plus ddNTP
--> used to prime and pre-prime --> ddNTP's get incorporated into the DNA --> chain-
terminating nucleotide analogs
chain-terminating nucleotide analogs
get incorporated into the DNA, but terminate stuff (only incorporated where C is in
template --> makes things with G at end of string)
how to find number of DNA molecules in a band:
base pairs X 650 daltons X 1mole/3.25e5 grams --> moles
moles X 6.02e23 molecules = molecule in band
coordinate control
control of multiple related genes with one operon
operator
DNA segment that acts as switch; controls access of RNA polymerase to the genes;
located within the promoter
trp operon
operon in tryptophan pathway
the trp operon is usually ____
on
how are the genes of the trp operon transcribed?
RNA polymerase binds to the promoter and transcribes
trpR
has its own promoter; expressed continuously
why are trp operons not permanently switched off?
1. binding of repressors is reversible
2. the trp repressor is an allosteric protein, with two alternative shapes --> one is active,
1 is inactive (synthesized in its inactive form, which doesn't bind to the repressor)
tryptophan repressor binding
solution
operon
a stretch of DNA consisting of an operator, a promoter, and genes for a related set of
proteins, usually making up an entire metabolic pathway
genes of an operon
arranged sequentially after the promoter
promoter
a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start
transcribing RNA at the appropriate place
regulatory gene
codes for a protein, such as a repressor, that controls the transcription of another gene
or group of genes
operator
regulatory proteins bind to the operator to control expression of the operon
repressor
a protein that inhibits gene transcription. In prokaryotes, the repressor binds to the
operator and blocks DNA polymerase from attaching to the promoter, which prevents
transcription
inducer
a specific small molecule that binds to a bacterial regulatory protein and changes its
shape so it can't bind to an operator, thus switching an operon on
replica plating
a way of screening a large number of mutants very efficiently
start with wild type organism, mutate it, then replica plating
lac Y
protein which allows bacteria to pick up lactose
permease-minus
mutant of bacteria without lac Y
lac Z
enzyme that cleaves the disaccharide of glucose into monosaccharides for energy
(mutant doesn't have this enzyme); gene for b-galactosidase
constitutive mutant
expressed lacZ and lacY even in the absence of lactose
negative control
inhibition of genes; regulation of trp and lac operons are this because operons are
switched off
polycistionic mRNA
codes for multiple proteins; has multiple start codons (as many start codons as there
are protein products)
southern blot
helps answer "is a particular DNA sequence present in this sample?"
southern blot mechanism
, restriction digest of DNA ---> electrophoresis ---> transfer of DNA from gel to membrane
surface (blotting) ---> probing with radioactive oligonucleotide ---> autoradiography
antisense RNA
complementary to mRNA
experiment with antisense RNA
sense RNA --> parent --> no effect in offspring
anti-sense RNA --> parent --> no effect in offspring
double-stranded RNA --> parent --> "twitching" offspring
catalytic
small number of double-stranded RNA eliminates all target RNA in the cells
rna induced silencing complex
there is point where one of the strands of double-stranded RNA gets kicked out of the
cell so only one strand is left
if bases of RNA are completely complementary....
the protein is degraded. Otherwise, the transaction is blocked
Sanger method
making DNA in the process: need polymerase, primers, template nntp's ---> plus ddNTP
--> used to prime and pre-prime --> ddNTP's get incorporated into the DNA --> chain-
terminating nucleotide analogs
chain-terminating nucleotide analogs
get incorporated into the DNA, but terminate stuff (only incorporated where C is in
template --> makes things with G at end of string)
how to find number of DNA molecules in a band:
base pairs X 650 daltons X 1mole/3.25e5 grams --> moles
moles X 6.02e23 molecules = molecule in band
coordinate control
control of multiple related genes with one operon
operator
DNA segment that acts as switch; controls access of RNA polymerase to the genes;
located within the promoter
trp operon
operon in tryptophan pathway
the trp operon is usually ____
on
how are the genes of the trp operon transcribed?
RNA polymerase binds to the promoter and transcribes
trpR
has its own promoter; expressed continuously
why are trp operons not permanently switched off?
1. binding of repressors is reversible
2. the trp repressor is an allosteric protein, with two alternative shapes --> one is active,
1 is inactive (synthesized in its inactive form, which doesn't bind to the repressor)
tryptophan repressor binding
