Study Guide

• what happens if beta galactosidase (lacZ gene) is inactivated?

  microbe can't grow on lactose
• what is the leader peptide in attenuation?


  short sequence of amino acids
• how does attenuation regulate the trp operon when trp is in excess?

  ribosome pauses at stop codon and forms rho independent termination loop
• how does attenuation regulate the trp operon when trp is deficient?

  ribosome pauses at trp codon, forms 2:3 loop that blocks termination loop formation
• what does high tryptophan inhibit in feedback inhibition?

  antrhonilate synthase
• what is the maltose operon an example of?

  positive regulation
• malT protein is an activator, increase transcription
• maltose is a co-activator, activates malT
• how is the lac operon regulated by catabolite repression?

  stops transcription when glucose is available
• what 2 molecules with the phosphotransferase system phosphorylate?

  glucose when present, otherwise adenylated cyclase
• what does adenylated cyclase do when phosphorylated/activated?

  catalyzes reaction of ATP to cyclicAMP
• what types of regulator is the cyclic AMP receptor protein?

  positive regulator synthesized in inactive state
• how is the cyclic AMP receptor protein activated?

  cAMP binding, increases lac operon transcription
• what is the role of proteases in heat shock response?

  remove denatured proteins
• what is the result of melting of secondary mRNA structure in heat shock response?

  increase translation of rpoH to sigma H
• when is rpoH transcription increase in heat shock response?

  when molecular chaperones are binding to denatured proteins
• quorum sensing in gram + bacteria regulates virulence factor production
• what gene produces auto inducing peptide?


  agrD
• AIP is the signal molecule for the 2-component regulator (agrA and agrC)
• AIP increases RNA3 expression by sarA activators
• what gene synthesizes the autoinducer in quorum sensing of gram - bacteria?

  luxI synthesizes acyl-homoserine-lactone
• what is the role of luxR gene in quorum sensing of gram - bacteria?

  regulator/activator, activated at high autoinducer concentration caused by high cell density
• how do riboswitches stop transcription?

  change secondary structure and block shine-delgarno sequence
• how does antisense RNA stop translation?

  binds to mRNA
• are plasmids or chromosomes larger?

  chromosomes
• what are the 3 ways plasmids are maintained in the cell?

  1. replication
  2. segregation
  3. toxin-antitoxin system
• what is the process of base excision repair?

  1. remove incorrect base and sugar phosphate backbone
  2. DNA polymerase replaces with correct base
• what is the process of methyl mismatch repair?

  1. MutS recognizes mismatch
  2. MutH identifies methylated strand and degrades damaged strand
  3. DNA polymerase 3 fills in the gap
• what is the process of recombination repair?

  1. regress replication fork and degrade damage
  2. exchange with undamaged strand and replicate
• what is the process of SOS repair?

  1. stall DNA polymerase
  2. randomly insert bases via error prone umuCD coplex
• what are 2 ways to mutagenize cells?

  1. mobile genetic elements
  2. replica plates
• how are transposons used for mutagensis?

  • transferable via plasmids
  • transcription and translation stop sequences stop gene expression
• what type of enzymes attack viral DNA in CRISPR?

  restriction enzymes
• what is guide RNA associated with in CRISPR?

  Cas9 nuclease
• what findings about transformation where made in the griffith experiment?

  DNA can be transferred from dead capsulated cells (virulent) to living non-capsulated cells, making them virulent
• when do frameshift mutations occur and what mutagen could cause them?

  during replication, intercalating dye
• of the 3 types of horizontal gene transfer, plasmids only transfer DNA in conjugation
• what is required to find ORFs?

  location of stop and start codons
• how does FISH help identify domains/genera/species?

  probe binding shows cells that are part of group of interest
• how does sanger sequencing work?

  identifies end nucleotide to make fragments and separate by size/base