Bacterial Genetics: Transformation and Conjugation
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Questions and Answers

Which enzyme stabilizes the unwound parental DNA during replication?

  • RNA polymerase
  • Helicase
  • DNA ligase
  • Proteins (correct)

    • What polymerase is responsible for synthesizing a short RNA primer on the lagging strand?

  • RNA polymerase (correct)
  • DNA polymerase
  • DNA ligase
  • Topoisomerase

    • Which enzyme is involved in continuously synthesizing the leading strand?

  • Helicase
  • DNA polymerase (correct)
  • DNA ligase
  • RNA polymerase

    • What is the role of DNA ligase in DNA replication?

    <p>Joins fragments of the lagging strand</p> Signup and view all the answers

    Which fragments are formed on the lagging strand during DNA replication?

    <p>Okazaki fragments</p> Signup and view all the answers

    Which process involves the synthesis of RNA from a DNA template?

    <p>Transcription</p> Signup and view all the answers

    What does DNA stand for?

    <p>deoxyribonucleic acid</p> Signup and view all the answers

    How are the nitrogenous bases adenine and thymine connected in DNA?

    <p>By two hydrogen bonds</p> Signup and view all the answers

    Which component is not a part of a nucleotide?

    <p>Lipids</p> Signup and view all the answers

    What is the direction of the DNA strand on the left side of the double helix diagram?

    <p>5' to 3'</p> Signup and view all the answers

    What type of sugar is found in DNA?

    <p>Deoxyribose</p> Signup and view all the answers

    Which enzyme is responsible for unwinding the DNA strands during DNA replication?

    <p>DNA Helicase</p> Signup and view all the answers

    In E. coli, approximately how long is the DNA relative to the cell?

    <p>1000 times longer</p> Signup and view all the answers

    Which enzyme is responsible for extending the RNA primer during replication on the lagging strand?

    <p>DNA Polymerase</p> Signup and view all the answers

    What percentage of the total cell volume does the DNA take up in E. coli?

    <p>10%</p> Signup and view all the answers

    Which of the following base pairings is correct in the structure of DNA?

    <p>A-T</p> Signup and view all the answers

    Which enzyme is involved in the transcription process?

    <p>RNA Polymerase</p> Signup and view all the answers

    What is the function of tRNA?

    <p>To transfer amino acids to the ribosomes for protein synthesis</p> Signup and view all the answers

    Which type of RNA contains the codons?

    <p>mRNA</p> Signup and view all the answers

    During transcription, in which direction is the mRNA synthesized?

    <p>5' to 3'</p> Signup and view all the answers

    Which of the following is NOT a component involved in the transcription process?

    <p>Ribosome</p> Signup and view all the answers

    How many amino acids are coded by the genetic code?

    <p>20</p> Signup and view all the answers

    How many possible combinations of 3-base codons exist?

    <p>64</p> Signup and view all the answers

    What is the term used to describe genes that are always turned on?

    <p>Constitutive</p> Signup and view all the answers

    Which of the following bases is NOT found in RNA?

    <p>T</p> Signup and view all the answers

    What role do codons play in the genetic code?

    <p>They code for a specific amino acid</p> Signup and view all the answers

    Which type of mutation does not alter the function of the protein?

    <p>Silent (neutral)</p> Signup and view all the answers

    Which process involves the uptake of naked DNA from the environment by a bacterium?

    <p>Transformation</p> Signup and view all the answers

    Which of the following is necessary for evolution in bacteria?

    <p>Genetic variation</p> Signup and view all the answers

    Genetic transfer in bacteria does NOT occur through which of the following methods?

    <p>Mitosis</p> Signup and view all the answers

    Which process of genetic transfer in bacteria involves a virus?

    <p>Transduction</p> Signup and view all the answers

    What happens to the DNA of bacterial cells when they die?

    <p>It is released into the surrounding medium.</p> Signup and view all the answers

    Which process involves DNA being transferred from one bacterium to another by a virus?

    <p>Transduction</p> Signup and view all the answers

    In conjugation, what structure is used to pass DNA between bacteria?

    <p>Sex pilus</p> Signup and view all the answers

    During bacterial transformation, where does a living bacterium obtain new DNA?

    <p>From the surroundings</p> Signup and view all the answers

    Which of the following terms best describes a virus that infects bacteria?

    <p>Bacteriophage</p> Signup and view all the answers

    What are the causes of genotypic variation in bacteria?

    <p>Mutation</p> Signup and view all the answers

    Which type of mutation involves the substitution of one nitrogenous base for another?

    <p>Substitution</p> Signup and view all the answers

    What is an example of a transversion mutation?

    <p>Substitution of adenine with thymine</p> Signup and view all the answers

    Which statement is true about genotypic variations?

    <p>They are heritable among bacterial generations</p> Signup and view all the answers

    By what mechanisms can a gene mutation be induced?

    <p>UV light</p> Signup and view all the answers

    What occurs in a deletion mutation?

    <p>A base is removed</p> Signup and view all the answers

    What is a characteristic of phenotypic variation in bacteria?

    <p>It is influenced by environmental conditions.</p> Signup and view all the answers

    Which substance interferes with the bacterial development of flagella?

    <p>Phenol</p> Signup and view all the answers

    What happens to bacterial cells with irregular staining when transferred to a fresh medium?

    <p>They return to normal morphology.</p> Signup and view all the answers

    Which factor influences the formation of capsules and spores in bacteria?

    <p>Composition of medium</p> Signup and view all the answers

    What is the relationship between young multiplying bacterial cells and their susceptibility to disinfectants?

    <p>Young multiplying cells are more susceptible.</p> Signup and view all the answers

    When does Escherichia coli synthesize the enzyme beta-galactosidase?

    <p>When grown in a medium containing lactose.</p> Signup and view all the answers

    Study Notes

    DNA Replication

    • Occurs at the replication fork (5' to 3')
    • Enzymes unwind the parental double helix
    • Proteins stabilize the unwound parental DNA
    • Leading strand is synthesized continuously by DNA polymerase
    • Lagging strand is synthesized discontinuously by RNA polymerase and DNA polymerase
    • RNA primer is digested and replaced with DNA
    • DNA ligase joins the discontinuous fragments of the lagging strand

    DNA Structure

    • Double-stranded (double helix)
    • Polymers of nucleotides
    • 5' to 3' (strands are anti-parallel)
    • Complimentary base pairing:
      • A-T
      • G-C

    DNA and RNA

    • DNA: deoxyribonucleic acid
    • RNA: ribonucleic acid
    • Nucleotides consist of:
      • Phosphate group
      • Pentose sugar
      • Nitrogenous base

    Genetic Code

    • Codons code for a specific amino acid
    • 20 amino acids
    • 3-base code (4^3 = 64 possible combinations)
    • Amino acids are coded for by more than one codon

    Transcription

    • One strand of DNA is used as a template to form a complementary strand of mRNA
    • 3 ways RNA differs from DNA
    • Promoter, RNA polymerase, and termination site are involved
    • 5' to 3' direction

    Types of RNA

    • mRNA: contains codons
    • rRNA: found in ribosomes (70S)
    • tRNA: transfers amino acids to ribosomes for protein synthesis
    • Anti-codon

    Mutations

    • Can be harmful, lethal, beneficial, or silent (neutral)
    • Examples: UUU - Phe, UUC - Phe

    Genetic Transfer in Bacteria

    • Results in genetic variation, necessary for evolution
    • 3 ways genetic transfer can occur in bacteria:
      • Transformation
      • Conjugation
      • Transduction

    Transformation

    • Genes are transferred from one bacterium to another as naked DNA
    • Bacterial cells uptake free DNA from the surrounding medium

    Conjugation

    • One bacterium passes some DNA (in a plasmid) to another bacterium

    Transduction

    • DNA is transferred from one bacterium to another by a virus (bacteriophage)

    Genetic Variation

    • Phenotypic variation:
      • Changes in bacterial characters in response to environmental conditions
      • Reversible when the environmental cause is removed
      • Not heritable (no genetic changes)
    • Genotypic variation:
      • Changes in the bacterial characters due to changes in the genetic constitution of the bacterial cell
      • Irreversible
      • Heritable among bacterial generations
    • Causes:
      • Mutation
      • Gene transfer

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    Description

    Learn about the processes of transformation and conjugation in bacterial genetics, including how DNA is released and taken up by bacterial cells.

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