Questions and Answers
Who discovered PCR and when?
Kary B. Mullis in 1983
Two sections of double stranded DNA cut by the same restriction enzyme will likely anneal naturally (on their own).
True
Reverse transcriptase catalyzes reverse transcription of DNA from RNA.
True
What are the 3 types of horizontal gene transfer among prokaryotes?
Signup and view all the answers
During bacterial conjugation, which cell initiates contact via a pilus?
Signup and view all the answers
Virulent phages integrate their genetic material into a bacterial cell's chromosome, and the host cell can continue to live and reproduce normally.
Signup and view all the answers
Viruses that only use the lytic cycle are called virulent phages.
Signup and view all the answers
Define/describe bacterial transformation.
Signup and view all the answers
Describe bacterial competence in the context of transformation.
Signup and view all the answers
Describe the 4 main conditions and outcomes of Frederick Griffith's experiment.
Signup and view all the answers
Frederick Griffith's experiment is a classic example of bacterial transformation.
Signup and view all the answers
Humans can only transfer genes vertically, while bacteria can only transfer genes horizontally.
Signup and view all the answers
Phages and antibiotics are both used as broad-spectrum tools for combating bacterial infections.
Signup and view all the answers
Transduction is the transfer of DNA from one host prokaryotic bacterium to another prokaryotic bacterium via a virus capable of infecting both the donor and recipient cells.
Signup and view all the answers
Describe the difference between generalized transduction and specialized transduction.
Signup and view all the answers
During gel electrophoresis, DNA is drawn towards the negative electrode, allowing one to separate molecules based on charge, size and shape.
Signup and view all the answers
During gel electrophoresis, larger fragments migrate faster and farther than smaller ones through the agarose gel.
Signup and view all the answers
In addition to DNA, PCR can be used to directly amplify RNA.
Signup and view all the answers
Study Notes
PCR and Its Discovery
- Polymerase Chain Reaction (PCR) was discovered by Kary B. Mullis in 1983, revolutionizing molecular biology techniques for amplifying DNA.
DNA Annealing and Restriction Enzymes
- Two sections of double-stranded DNA cut by the same restriction enzyme can anneal naturally but require DNA ligase to seal gaps in the phosphodiester backbone.
Reverse Transcriptase Functionality
- Reverse transcriptase catalyzes the synthesis of DNA from an RNA template, playing a crucial role in retroviral replication.
Horizontal Gene Transfer in Prokaryotes
- Three primary types of horizontal gene transfer among prokaryotes: transduction, transformation, and bacterial conjugation.
Bacterial Conjugation
- In bacterial conjugation, the donor cell is responsible for initiating the contact with the recipient cell through a specialized structure called a pilus.
Virus Life Cycles
- Virulent phages operate solely via the lytic cycle, resulting in cell lysis, while temperate phages can integrate their genetic material into the host chromosome during the lysogenic cycle.
Bacterial Transformation
- Transformation occurs when a bacterial cell captures naked or exogenous DNA from its environment, requiring the bacterium to be in a “competent state” to uptake the DNA.
Bacterial Competence
- During transformation, bacterial competence is achieved when the bacterial cell membrane and wall are made more permeable, often induced by heat-shock, to facilitate DNA uptake.
Frederick Griffith's Experiment
- Griffith's experiment uncovered key principles of bacterial transformation:
- Rough strain (non-virulent) → mouse survives
- Smooth strain (virulent) → mouse dies
- Heat-killed smooth strain → mouse survives
- Rough + heat-killed smooth strain → mouse dies
Griffith's Contributions
- Frederick Griffith's work serves as a classic illustration of bacterial transformation through the incorporation of genetic material from dead virulent bacteria by live non-virulent strains.
Gene Transfer Mechanisms
- Humans transfer genes only vertically (from parent to offspring), while bacteria can transfer genes both horizontally (across individuals) and vertically.
Phages vs. Antibiotics
- Antibiotics generally act as broad-spectrum agents against bacteria, while phages are highly specific to their target bacterial strains.
Transduction Definitions
- Transduction involves the transfer of DNA via a virus from one host bacterium to another and can occur between both prokaryotic and eukaryotic cells.
Generalized vs. Specialized Transduction
- Generalized transduction involves the random transfer of DNA segments, independent of specific sequences, whereas specialized transduction transfers specific DNA sequences along with viral DNA.
Gel Electrophoresis Mechanics
- Gel electrophoresis separates DNA molecules based on charge, size, and shape; negatively charged DNA moves toward the positive electrode, not the negative one.
Migration of DNA Fragments
- In gel electrophoresis, smaller DNA fragments migrate faster and travel farther through the agarose gel than larger fragments due to size constraints.
PCR Amplification Limitations
- PCR is designed to amplify DNA; it cannot directly amplify RNA without prior conversion to complementary DNA (cDNA).
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
