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Microbial Genetics Ch. 1-4


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Polymerization Reaction Step 1?
RNA and DNA first bind making a closed complex
Polymerization RXN step 2?
DNA strands pull apart to make an open complex
Polymerization RXN after open complex?
Ribonucleoside triphosphate bonds to template at start site.
Polmerization RXN step after binding at start site?
RNA polymerase catalyzes the reaction in which the alpha phosphate of the second nucleotide joins w/the 3' hydroxyl of the first nucleotide.
Polymerization RXN after polymerase catalysis and before the transcription bubble forms?
The RNA polymerase holoenzyme loses or releases its sigma factor.
Polymerization RXN after sigma factor is released.
The transcription bubble of DNA-RNA hbrid forms. It is about 18 bases long and holds the RNA polymerase.
Last step of Polymerization RXN, aftr the DNA-RNA hybrid forms?
Antiparallel complementary copy (transcript) is made on one strand of dna in a particular.
1 Cause of Pausing- helped by attenuation.
Hairpins cause the 3' end of the RNA to be displaced from the active center.
1 Cause of Pausing- occurs where there might be a string of U's.
RNA Bactracking- where RNA polymerase is weak ( because U is weaker than C...)
3 different RNA
20 different Amino Acids
enormous enzyme that polymerizes specific amino acids into polypeptide chains w/mRNA as a guide.
Whole Unit of RNA
30 S
21 different proteins initiated translation by binding to mRNA and then to the second part of RNA.
50 S
31 different proteins- forms peptide bonds and translocates the nucleic acid.
DNA strand that is copied
transcribed strand
DNA strand that isn't copied
coding strand
This attaches methionine to the tRNA
this adds a formy group to form the fMet-tRNAfmet.
transformylase enzyme
this removes the n-terminal methionine
the enzyme methionine aminopeptidase
a 5-10 nucleotide set on 5' ide that define a TIR. are complementary to short sequnces w/in regions of 16S.
Shine-Dalgarno sequence
Factor-independent termination
2 sequences- inverted repeat
Factor-dependent termination
pho termination: short string of amino's; RNA forms a hairpin which destroys the DNA-RNA hybrid.
Translational Fusions
2 coding sequences are cloned so they are translated into the tsame frame w/no nonsense codons b/w them. this makes a fuision protein w/either amino terminus or carboxyl terminus.
RNA precursors
sugar ribose at 2nd carbon, uracil, bases 5'-3', phosphates 3'-5'.
unpaired region pairs w/another in hairpin to form a knot: held weakly together by H bonds.
secondary structure of RNA
paired strands are antiparallel and stiff.
tertiary structure of RNA
the RNA is stiffer, folds back on self, has pseudoknots.
polycistronic mRNA
more than one TIR to allow simulataneous translation of more than one sequence of mRNA.
3' untranslated region
region between the last codon and the 3' end
ambiguity in translation
specify differently at certain locations of mRNA (UGA is example).
Nonsense codons
VAA, VAG, UGA: don't encode amino acids, they terminate.
spontaneous mutagenesis
occur normally as mistakes in DNA replication; rarer but less likely to contain more than one kind of mutation; can be base pair changes, duplications, insertions, deletions, frameshifts, etc.
induced mutagenesis
treating the ells w/some chemicals or with some types of irradation by iducing. can get only one particular type of muatation.
geneticcomposition, lacZ
observable or detectable property, LacZ
single set of genes- 1 copy
different or alternative forms of a particular gene proA58, pro A79
mutant (doesn't have function), absence of phenoytpe
organism with two identical alleles
organism with two different alleles.
wild type strain
arbitrarily chosen strain
isogenic sequence
mutant strain
any changes or mutations in DNA w/respect to wild-type strain.

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