Mircobiology exam 2

What are the types of symbiotic relationships in microbial communities?

Mutualism, commensalism, parasitism, and neutralism.

Define mutualism in microbial interactions.

A relationship where both organisms benefit from the interaction.

What is the difference between resident microbiota and transient microbiota?

Resident microbiota are permanent residents, while transient microbiota are temporary visitors.

What is binary fission?

The most common replication mechanism where a single cell divides into two identical daughter cells.

What is generation time in bacterial growth?

The time it takes for a bacterial population to double in number.

What role do biofilms play in microbial communities?

Biofilms are structured communities of microorganisms that adhere to surfaces and exhibit enhanced survival and resistance.

What defines obligate anaerobes?

Microorganisms that cannot survive in the presence of oxygen and require anaerobic conditions.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What function do extracellular polymeric substances serve in biofilms?

They help to maintain the biofilm structure and provide protection to the microbes.

What is the purpose of fermentation in microbial metabolism?

To regenerate NAD+ in the absence of oxygen, allowing glycolysis to continue.

How does temperature affect microbial growth?

Different microbes have optimal, minimum, and maximum temperatures for growth, such as psychrophiles thriving in colder conditions.

What is the role of ATP synthase in cellular respiration?

ATP synthase synthesizes ATP from ADP and inorganic phosphate, utilizing energy from proton gradients.

Describe the structure of a prokaryotic ribosome.

Prokaryotic ribosomes are composed of a small 30S subunit and a large 50S subunit, forming a 70S ribosome.

What are point mutations?

Genetic alterations where a single nucleotide change occurs in a DNA sequence.

Explain the significance of plasmids in bacteria.

Plasmids are extrachromosomal DNA that can carry genes contributing to traits such as antibiotic resistance.

What is the central dogma of molecular biology?

The process of converting DNA to RNA (transcription) and RNA to protein (translation).

Define competitive inhibition in enzyme function.

A competitive inhibitor binds to the active site of an enzyme, preventing substrate binding.

What distinguishes facultative anaerobes from obligate aerobes?

Facultative anaerobes can grow with or without oxygen, while obligate aerobes require oxygen for growth.

How do halophiles adapt to high salt concentrations?

Halophiles thrive in salty environments by maintaining osmotic balance through special adaptations.

What is the function of helicase in DNA replication?

Helicase unwinds and separates the double-stranded DNA, creating a replication bubble.

What is quorum sensing?

A cellular communication process that bacteria use to coordinate their behavior in response to population density.

What do acidophiles require for optimal growth?

Acidophiles thrive in environments with low pH, typically below 5.55.

Explain what is meant by gene expression.

The process by which information from a gene is used to synthesize proteins or RNAs.

What are noncoding DNA sequences?

Sequences of DNA that do not code for any proteins but may have regulatory or structural functions.

What happens during the lag phase of microbial growth?

During the lag phase, microbial cells are adapting to a new environment and there is little to no cell division.

What distinguishes a missense mutation from a nonsense mutation?

A missense mutation results in a change in the amino acid sequence, while a nonsense mutation creates a stop codon, terminating translation prematurely.

Describe the principal characteristics of chemotrophs.

Chemotrophs obtain energy from chemical compounds, either organic or inorganic, for their metabolic processes.

What is the purpose of RNA polymerase during transcription?

RNA polymerase synthesizes RNA by adding ribonucleotides complementary to the DNA template.

What defines a facultative anaerobe?

An organism that prefers oxygen but can survive without it, utilizing fermentation instead.

Define horizontal gene transfer.

The transfer of genetic material between organisms without the requirement for reproduction.

What is the significance of supercoiling in DNA structure?

Supercoiling allows DNA to be compacted and properly organized within the cell.

Explain how the structure of enzymes relates to their function.

The specific three-dimensional shape of enzymes allows them to bind to substrates and catalyze reactions efficiently.