Life Sciences Unit 3 - Microbiology

What are the three major domains of life?

Archaea, Bacteria, and Eukarya.

What distinguishes prokaryotic cells from eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.

What is the significance of the first archaea dating back to 3.5 billion years ago?

It indicates the ancient origins of life and the evolutionary timeline of organisms.

What are the key groups of archaea and their environments?

Methanogens (moderate environments), Thermophiles (extremely hot temperatures), Halophiles (salty conditions).

What are the characteristics of Gram-positive bacteria?

They have thick cell membranes and a single membrane structure.

What are the characteristics of Gram-negative bacteria?

They have thinner cell membranes and a double membrane structure.

What is the role of cyanobacteria in the ecosystem?

They are the only prokaryotes that use photosynthesis to produce food.

How do bacteria reproduce?

Through binary fission, where a bacterium splits in half to produce identical offspring.

What is quorum sensing in bacteria?

A communication process that allows bacteria to coordinate behavior based on cell density.

What are the two main cycles of viral replication?

The lytic cycle (where the virus destroys the host cell) and the lysogenic cycle (where the viral DNA integrates into the host's DNA).

What is the function of antibiotics?

They target and destroy bacteria by damaging their cell walls or blocking protein production.

What is the difference between antibiotics and antivirals?

Antibiotics target bacteria, while antivirals target viruses.

What is the purpose of a vaccine?

To expose the body to a weakened or inactive form of a pathogen to stimulate an immune response.

What is herd immunity?

Protection from infectious diseases that occurs when a significant portion of a population is vaccinated.

What is the role of antibodies in the immune system?

They are proteins made by B cells that help fight pathogens.

What is the primary function of the immune system?

To protect the body against pathogens such as bacteria, viruses, and fungi.

What are the first lines of defense in the immune system?

Skin and mucous membranes.

What are the two types of white blood cells involved in the immune response?

B cells and T cells.

What is the role of memory B and T cells?

They remember pathogens and enable a quicker immune response upon re-exposure.

What is the structure of a virus?

Viruses consist of genetic material (DNA or RNA) surrounded by a protein coat (capsid).

What is the significance of plasmids in bacteria?

Plasmids are small rings of DNA that can carry genes, including those for antibiotic resistance.

What is the function of pili in bacteria?

Pili allow bacteria to adhere to surfaces and other cells.

What are the nutritional types of bacteria based on energy and carbon sources?

Photoautotrophs (sunlight), Chemoheterotrophs (organic compounds), Lithotrophs (inorganic compounds).

What is the term for the process by which bacteria can acquire new genetic material?

Horizontal gene transfer.

What is the impact of viral mutations on vaccines?

Viruses can mutate frequently, making vaccines less effective over time.

What is the controversy surrounding the MMR vaccine?

Some believed it led to autism, but correlation does not imply causation.