microbial genetics

• DNA

  Double-stranded, anti-parallel structure from dATP monomer nucleotide
• RNA


  Single-stranded structure from ATP monomer nucleotide
• DNA Base Pairing Rules

  A-T, G-C
• RNA Base Pairing Rules

  A-U, G-C
• mRNA


  Messenger molecule transcribing DNA instructions for protein synthesis
• tRNA


  Transport molecule carrying specific amino acids to mRNA/ribosome complex
• rRNA


  Ribosomal molecule forming the ribosome with proteins
• Replication


  Process of synthesizing new DNA strands from existing ones (5' to 3')
• Unwinding Proteins

  Proteins breaking hydrogen bonds to separate DNA strands
• RNA Polymerase

  Enzyme synthesizing RNA complementary to DNA template
• DNA Polymerase

  Enzyme extending DNA strands by adding complementary nucleotides
• DNA Ligase


  Enzyme sealing adjacent DNA fragments in replication
• Transcription

  Process of transcribing DNA into RNA by RNA polymerase (5' to 3')
• Translation


  Process of synthesizing proteins from mRNA instructions
• Codon

  Triplet of nucleotides on mRNA coding for specific amino acids
• Gene Regulation

  Control of gene expression through repression and activation
• Mutation


  Genetic change due to errors in replication, chemicals, or radiation
• Plasmid


  Circular DNA transmitting genetic information between cells
• Transformation


  Uptake of DNA from the environment by a cell
• Conjugation


  Direct transfer of DNA between bacterial cells
• Resistance Factors

  Genes on plasmids/episomes conferring resistance to toxins
• Generalized Transduction


  Virus transferring random DNA from one host to another
• Specialized Transduction


  Virus transferring specific DNA near its insertion site
• Silent outcome of mutation


  Due to redundancy in the genetic code, more than one codon, may call for the same amino acid
• Neutral outcome of mutation


  Does not affect the function of the protein
• Harmful protein outcome of mutation


  Has less function or causes some deleterious result
• Beneficial outcome of mutation

  Rare but powerful, more likely preserved in later generations
• F+

  Only transfers F + altering the cell to F +
• Hfr

  high frequency of recombination transfers only a small piece of F + DNA and some chromosome DNA receipt will never become F +, but will receive chromosomal DNA
• Why are mutation and recombination important for the survivability of a population?

  Mutation and recombination tend to increase the variability in a population. Diversity of characteristics in individuals in a population helps insure that some individuals in the population will have the sufficient necessary characteristics for survival.See an expert-written answer!We have an expert-written solution to this problem!
• What precisely is the nature of DNA damage when UV is the initiating agent?

  Chemical fusion of adjacent thymines in a single strand
• Replication

  1. Unwinding proteins break the hydrogen bonds holding the two DNA strands together

  2. RNA polymerase binds a portion of the single stranded DNA and synthesizes a short complementary, anti-parallel RNA

  3. DNA polymerase binds to the short RNA primer and extends off of it making new DNA anti-parallel and complementary to the single stranded DNA

  4. DNA polymerase can excise RNA primers and replace the RNA with DNA completing a DNA complementary strand

  5. DNA ligase seals the adjacent DNA fragments after DNA polymerase has finished excising RNA primer and refilling with DNA nucleotides
• Replication occurs simultaneously on both strands so at completion there are two complete DNA molecules
• Transcription

  RNA polymerase binds the start of a gene, and synthesize a singe stranded RNA complimentary to one of the DNA strands. Synthesis is complementary, anti-parallel and in the 5' to 3’ direction
• Ribosome binds mRNA and synthesizes polypeptide chain


  1. Ribosome binds to 5' end of mRNA

  2. Ribosome moves 'downstream' until it finds first AUG

  3. AUG is always the first codon, subsequent codons are gene specific

  4. tRNA with complementary anti-codon binds to codon and carries corresponding amino acid

  5. Ribosome excises 1st amino acid off 1st tRNA and attaches to 2nd amino acid on 2nd tRNA

  6. Ribosome shifts 3 nucleotides down mRNA, 1st tRNA falls away, 3rd tRNA with anticodon and corresponding amino acid binds

  7. Ribosome continues down mRNA, attaching growing polypeptide chain to next amino acid