60 Questions
Who invented the microscope and described the first microbes?
Robert Hooke
Which scientist observed the first single-celled organisms, such as bacteria?
Antonie van Leeuwenhoek
Who conducted the 'meat/flies experiment' that disproved the idea of spontaneous generation for large organisms?
Francesco Redi
Which scientist sterilized meat broth by boiling, demonstrating that it failed to grow microbes?
Lazzaro Spallanzani
What theory proposed that living creatures could arise without parents?
Spontaneous Generation
'Spontaneous Generations' was disproved by which scientist's experiment involving meat and flies?
Francesco Redi
Who disproved the theory of spontaneous generation through the Swan-necked flask experiment?
Louis Pasteur
What does each colony/spot of bacterial growth represent?
A clonal population replicating from one original cell
Who discovered the solid medium using agar for bacterial culture to grow?
Angelina & Walther Hesse
Which postulate of Koch's postulates states that the suspected organism should be present in ALL cases of the disease & absent from healthy individuals?
Postulate #1
What is the main limitation of Koch's postulates in identifying pathogens and diseases?
Pathogens may not be culturable with known techniques
What is stromatolite clear fossilized evidence of?
Bacterial communities
What is the prebiotic soup a hypothetical set of conditions for?
Formation of small organic molecules on early Earth
What was produced by the Miller-Urey experiment under simulated prehistoric Earth conditions?
"Molecules of life" like amino acids and their derivatives
What model suggests self-sufficient abiotic chemical reactions formed cellular metabolism?
Metabolist Model
Which molecule is suggested to be a precursor to DNA and has catalytic activity?
RNA
What does the molecular clock measure?
Time information contained in macromolecular sequence
What does the Shine-Dalgarno sequence allow on mRNA?
Binding to ribosomes in prokaryotes
What is the main point of the endosymbiont theory?
Eukaryotic cells originated from prokaryotic organisms
What is a characteristic of bacterial genomes?
Contain a significant amount of non-coding DNA
Which process involves the transfer of DNA from the environment into a bacterial cell?
Transformation
What is the main function of bacteriophages?
Inject viral DNA into bacterial cells
Which statement best describes horizontal gene transfer in bacteria?
Genes are acquired from the environment by the bacteria themselves
What is a characteristic of gram-negative bacteria?
Enhanced competence due to low temperature
What is the fate of most foreign DNA entering a bacterial cell?
Degradation by restriction endonucleases
What is the role of Recombination proteins (Rec) in bacteria?
Mediate the combination of two DNA molecules with specific homologous sequences
What is the primary function of operons in bacteria?
Regulate the expression of structural genes through DNA control sequences
What is an example of genomic island regions in bacterial genomes?
Regions with signs of horizontal gene transfer
What is a characteristic feature of the nucleoid in bacterial cells?
Forms loops of chromosomes called domains
How do mitochondria behave like endosymbiotic organisms?
Live inside another organism and reproduce independently
During DNA replication, which enzyme is responsible for synthesizing new DNA strands?
DNA polymerase III
What is the primary function of RecA during DNA recombination?
Invading recipient & donor to homologous stretch of recipient
Which enzyme catalyzes the breaking and rejoining event that passes the chromosomes at the termination of DNA replication?
Topoisomerase IV
What is the function of RNase H during the completion of DNA replication?
Removes the RNA primers
What is the primary role of DNA primase in DNA replication?
Producing RNA primers
Which type of mutation involves a change in a single base?
Transition
What is the function of photolyase enzyme in DNA repair?
Binding to pyrimidine dimer and cleaving the cyclobutane ring under UV radiation
What is the primary function of RecBCD protein machine in DNA recombination?
Unwinding donor DNA
What type of replication occurs for cellular DNA in most cases?
Semiconservative
Which enzyme is responsible for keeping the single DNA strands apart during DNA synthesis?
SSBs (single-stranded DNA binding proteins)
What do base analogs do during DNA replication?
Introduce mutations due to incorrect pairing
What type of mutation changes the amino acid sequence to a stop codon?
Nonsense mutation
What is the function of the O-specific polysaccharide in Lipopolysaccharide (LPS)?
It forms a protective and stabilizing layer
Which type of transport involves the movement of molecules against the gradient and requires energy?
Active transport
What is the main function of ABC Transporters?
Provide energy for primary active transport
What is the role of the phosphotransferase system (PTS) in bacterial cells?
Drive entry of glucose by modifying it to G6P
Which system is responsible for the transport of unfolded proteins requiring ATP hydrolysis to move out of the cell?
Sec System
What is the main function of the Sec-dependent secretion proteins?
Move signal-peptide containing proteins into periplasm
Which bacterial secretion system is used to inject toxins/harmful molecules into other cells?
Type VI
What is the main function of Glycocalyx?
- It serves as a network of polysaccharides from cell surface
What does the Proton-Motive Force promote?
- Movement of protons across membranes downhill the electrochemical potential
What is the function of Capsule in bacterial cells?
- It forms an organized glycocalyx that is difficult to remove
What is the purpose of Type III bacterial secretion system?
- Inject toxins/harmful molecules into other cells
Which repair mechanism recognizes and repairs bases that (mostly) do not distort DNA structure?
Base-excision repair
What is the function of DNA ligase in the excision repair process?
Seals the broken ends of DNA back together
In the SOS response, what is the role of RecA?
Inactivates LexA when DNA is damaged
Which process requires homology and is RecA mediated?
Double-strand break repair
What is the function of Rho in Rho-dependent termination?
Binds mRNA & moves along
What is the role of Sigma70 factor in transcription?
Needed for gene homeostasis
Which structure serves as a permeability barrier in bacterial cells?
Cell membrane
Test your knowledge on the process of DNA recombination, including steps such as unwinding donor DNA, RecA binding, invasion of recipient DNA, and repair of breaks. Learn about the difference between generalized and site-specific recombination.
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