Exam 2 Total Review (Hard)

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Questions and Answers

What distinguishes mesophiles from other types of microbes in terms of temperature preference?

They thrive at temperatures below freezing.

They grow at human body temperature. (correct)

They require very high temperatures for growth.

They are unable to grow outside of cold environments.

How does Helicobacter pylori manage to survive in the acidic environment of the stomach?

It produces urease to neutralize acidity. (correct)

It secretes mucous to coat itself.

It absorbs and pumps out the acidic content.

It produces a protective biofilm.

What is the primary difference between complex and synthetic media in microbiology?

Synthetic media has an unknown composition of nutrients, while complex media has a defined chemical structure.

Complex media is composed of a known mixture, while synthetic media has known components. (correct)

Complex media comprises organic components, whereas synthetic media includes only inorganic nutrients.

Synthetic media is undefined while complex media is defined.

In the context of Frederick Griffith's experiments, what did the observation of the transformation principle confirm?

Genetic material can transform non-virulent bacteria into virulent forms. Signup and view all the answers

What was the significant finding from the experiments conducted by Oswald Avery and his colleagues regarding genetic material?

DNA, not protein, is the genetic material responsible for inheritance. Signup and view all the answers

What are the primary roles of DNA in cellular functions?

Replication and gene expression. Signup and view all the answers

What key difference exists between polycistronic and monocistronic mRNA?

Monocistronic mRNA codes for only one protein from one gene. Signup and view all the answers

What is the function of the Shine-Dalgarno sequence in prokaryotic mRNA?

It serves as the binding site for ribosomes to initiate translation. Signup and view all the answers

What is the result of a nonsense mutation in a gene?

It creates a premature stop codon, truncating the protein. Signup and view all the answers

Which of the following characteristics of eukaryotic transcription differs from that of prokaryotic transcription?

Eukaryotic mRNA undergoes splicing before translation. Signup and view all the answers

What is the primary mechanism by which transformation occurs in bacteria?

Uptake of naked DNA from the environment Signup and view all the answers

Which of the following correctly describes the lytic cycle of bacteriophage replication?

New viruses are released by causing the host cell to burst Signup and view all the answers

What is the role of restriction endonucleases in genetic engineering?

To cut DNA at specific sequences Signup and view all the answers

Which statement distinguishes Hfr cells from F+ and F- cells?

Hfr cells contain the F plasmid integrated into their chromosomes Signup and view all the answers

What is generation time in bacterial growth?

Time between successive binary fission of a cell Signup and view all the answers

What occurs during nucleotide excision repair?

Damaged DNA segments are removed and replaced Signup and view all the answers

In blue-white screening, what color will colonies containing recombinant plasmids appear?

White Signup and view all the answers

Which stage of the bacterial growth curve is characterized by a plateau in the number of living bacterial cells?

Stationary phase Signup and view all the answers

Which of the following accurately describes specialized transduction?

Transfer of specific bacterial genes near prophage sites Signup and view all the answers

During which phase of bacterial growth would symptoms of disease typically develop?

Log phase Signup and view all the answers

What does competence refer to in bacterial cells?

Ability to take up extracellular DNA Signup and view all the answers

What is the primary purpose of the streak plate method in microbiology?

To isolate pure bacterial colonies Signup and view all the answers

What does it mean for an organism to be classified as VBNC?

It is a living organism that cannot be detected in standard lab conditions Signup and view all the answers

What is the function of a repressor protein in an operon?

To bind to the operator and inhibit transcription Signup and view all the answers

Which of the following statements is true regarding vertical gene transfer?

It is the transfer of genes from parent to offspring Signup and view all the answers

Which organisms are capable of undergoing aerobic respiration?

Obligate aerobes, facultative anaerobes, and microaerophiles Signup and view all the answers

What is the primary function of the Gaspak system in microbiological studies?

To create an anaerobic environment for culturing anaerobes Signup and view all the answers

Which of the following pH classifications refer to organisms that thrive in acidic conditions?

Acidophiles Signup and view all the answers

At what temperature range do mesophiles grow best?

20-45 degrees Celsius Signup and view all the answers

What role does the catalase test serve in microbiology?

It detects catalase enzymes involved in detoxifying hydrogen peroxide Signup and view all the answers

Study Notes

Restriction Endonucleases

Enzymes that cut DNA at specific nucleotide sequences, called restriction sites
Recognize palindromic sequences
Make cuts, either blunt or sticky ends

Competence

Ability of a cell to take up extracellular DNA from its environment during transformation.

Ways to achieve competence

Natural competence: Some bacteria naturally take up DNA under certain conditions
Chemical competence: Cells are treated with calcium chloride to increase membrane permeability
Electroporation: An electric field is applied to create temporary pores in the cell membrane, allowing DNA to enter
Heat shock: Cells are exposed to a sudden increase in temperature, creating membrane pores for DNA uptake

Molecular Cloning Steps

Isolation of the DNA of interest: The gene to be cloned is cut using restriction enzymes.
Insertion into a vector: The isolated DNA is ligated (joined) into a cloning vector (e.g., plasmid).
Transformation into a host cell: The recombinant vector is introduced into a competent host cell, usually bacteria.
Selection of recombinant cells: Cells that have successfully taken up the recombinant DNA are selected using antibiotic resistance or reporter genes.

Blue-White Screening

Technique used to differentiate between bacterial colonies that contain recombinant plasmids and those that do not.
Bacteria with non-recombinant plasmids produce a blue color (due to β-galactosidase activity).
Bacteria with recombinant plasmids (insertion of foreign DNA disrupts the lacZ gene) produce white colonies, indicating successful cloning.

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Description

Test your knowledge on molecular cloning techniques, including the role of restriction endonucleases, the concept of competence, and methods to achieve it. This quiz will cover various processes such as DNA isolation, vector insertion, and transformation into host cells.