Microbiology: Microbial Diversity, Genetics, Growth & Lab Tests

What is a key structural feature of eukaryotic cells?

They have a nucleus.

What type of chromosomes do eukaryotic cells possess?

Linear chromosomes.

Name three membranous organelles found in eukaryotic cells.

Endoplasmic reticulum (ER), Golgi apparatus, and vacuoles.

What organelles are involved in energy production in eukaryotic cells?

Mitochondria and chloroplasts.

What are single-celled fungi called?

Yeasts.

What is the structure formed by fungal hyphae?

Mycelium.

What is the primary component of fungal cell walls?

Chitin.

What are the two major groups of amebas?

Lobed amebas and filamentous amebas.

What disease is caused by Naegleria fowleri?

Primary amebic meningoencephalitis.

What is the function of cilia in ciliates?

Ciliates use cilia for movement and feeding.

What is the apical complex in apicomplexans?

A specialized structure that facilitates entry of the parasite into a host cell.

What is the vector for malaria?

Mosquitoes (specifically, Anopheles mosquitoes).

What are helminths?

Parasitic worms.

What are the three main types of helminths?

Nematodes (roundworms), trematodes (flukes), and cestodes (tapeworms).

What is a characteristic of nematodes?

They have a cylindrical shape and a digestive tube that ends in an anus.

What is a common example of a cestode?

Tapeworms.

What are arthropods known for?

Having an exoskeleton and jointed appendages.

What is a common disease transmitted by ticks?

Lyme disease.

What is a virus?

A noncellular particle with a genome contained by a capsid.

What are bacteriophages?

Viruses that infect bacteria.

What is a virion?

Progeny viruses.

What is the Baltimore model?

A classification system for viruses based on their genome type.

What type of viruses does Group I of the Baltimore classification include?

Double-stranded DNA viruses.

What disease is caused by the herpesvirus?

Chickenpox and genital infections.

What type of viruses does Group IV of the Baltimore classification include?

Sense single-stranded RNA viruses.

What disease is caused by orthomyxoviruses?

Influenza.

What is a characteristic of viral genomes?

They can be RNA or DNA, and single-stranded or double-stranded.

What is the significance of the capsid in viruses?

It keeps the viral genome intact outside the host cell.

What type of viruses are retroviruses?

RNA reverse transcribing viruses

What diseases do lentiviruses like HIV cause?

AIDS and simian AIDS

What are pararetroviruses?

DNA reverse-transcribing viruses

What is the role of caulimoviruses in biotechnology?

They provide vector tools for plant biotechnology.

What type of virus is Hepatitis B?

A hepadnavirus that infects the human liver.

What is the structure of an icosahedral capsid?

It has radial symmetry based on an icosahedron with 20 identical triangular faces.

Give an example of a virus with a filamentous structure.

Tobacco mosaic virus or Ebola virus.

What is a viral envelope?

An optional structure derived from the host's membrane that may contain spike proteins.

What are complex-tailed bacteriophages?

Viruses with an icosahedral head and a tail that injects genetic material into host cells.

What are viroids?

Virus-like infectious agents where the genome is the entire infectious particle, targeting plants.

What are prions?

Infectious proteins that cause forced misfolding of normal proteins.

What is antigenic drift?

Rapid mutation leading to new strains of viruses that may evade host antibodies.

What is the difference between lytic and lysogenic infections?

Lytic infections result in the rupture of host cells, while lysogenic infections integrate into the host genome.

What is the significance of the HPV link to cervical cancer?

Harald zur Hausen discovered the link, earning him the 2008 Nobel Prize in Physiology.

What is the structure of SARS-CoV-2?

It contains RNA packaged in proteins with a surrounding envelope and spike proteins.

What is the role of hemagglutinin in the influenza virus?

It helps the virus attach to host cells.

What is the function of reverse transcriptase in HIV?

It synthesizes DNA from the RNA template.

What is CAR-T therapy?

A treatment that modifies T cells to target certain forms of leukemia.

What is the purpose of bacterial culture media?

To grow bacteria either in liquid or solid form for laboratory studies.

What is isolation streaking?

A technique used to separate bacterial colonies into pure culture.

What does a minimal medium contain?

Only the nutrients necessary for the organism to grow.

What is the significance of the spread plate technique?

It allows for the isolation of pure colonies from a mixed culture.

What is the primary target of HIV?

Helper T cells, which are immune cells.

What is the prognosis for untreated AIDS?

Death due to opportunistic infections.

What is the mode of transmission for prions?

Consumption of prion-infected material, typically meat.

What are oncogenes?

Genes that can cause cancer when inserted by viruses.

What is the role of neuraminidase in influenza virus replication?

It assists in the budding process of new virions.

What is a minimal medium?

A synthetic medium with only the nutrients an organism needs to grow.

What is a rich medium?

A nutrient-rich but less defined complex medium used for bacterial growth.

What is selective media?

Media that prevent the growth of some bacteria while favoring the growth of specific types.

What is differential media?

Media where species grow equally well but can be distinguished by color indicators.

What is MacConkey medium used for?

To selectively grow Gram-negative enteric bacteria and differentiate lactose fermenters.

What methods count only live bacterial cells?

Plated (growth) methods.

What are direct cell counts?

Methods that determine the total number of cells, dead or alive.

What is binary fission?

The process by which most bacteria reproduce, dividing one parent cell into two daughter cells.

What is exponential growth in bacteria?

Growth where the population size doubles at a fixed rate, such as every 20 minutes.

What are essential nutrients for microbes?

Compounds that a microbe cannot synthesize and must obtain from the environment.

What are some examples of essential nutrients?

Carbon, nitrogen, phosphorus, hydrogen, oxygen, sulfur, magnesium, iron, potassium, and trace elements.

What are growth factors?

Compounds that must be added to culture media for certain microbes to grow.

What is the role of carbon compounds in microbial life?

They serve as food, storing energy and providing building materials for biomass.

What are autotrophs?

Organisms that make their own carbon compounds from CO2.

What are chemotrophs?

Organisms that use oxidation-reduction reactions to obtain energy.

What is nitrogen fixation?

The process by which some bacteria convert N2 gas to ammonium ions (NH4+).

What are extremophiles?

Microbes that can grow in extreme environments, such as high temperatures or pressures.

What are psychrophiles?

Bacteria that grow at temperatures of 20°C or lower.

What are mesophiles?

Bacteria that grow best at temperatures between 15°C and 45°C.

What are thermophiles?

Bacteria that thrive at temperatures typically between 55°C and 70°C.

What are barophiles?

Microorganisms that have adapted to grow at high pressures, such as those found deep in the ocean.

What is water activity (aw)?

A measure of the availability of water for microbial growth.

What are halophiles?

Microbes that require high concentrations of salt (NaCl) for growth.

What pH range do neutralophiles prefer?

A pH range between 5 and 8.

What are strict aerobes?

Organisms that require oxygen for energy metabolism and can detoxify reactive oxygen species (ROS).

What are strict anaerobes?

Organisms that do not require oxygen for energy metabolism and find oxygen toxic.

What is a biofilm?

A mass of bacteria that stick to and multiply on a solid surface, often resistant to destruction.

What are endospores?

Dormant, destruction-resistant forms produced by certain Gram-positive bacteria.

Which bacteria are known for producing endospores?

Bacillus (e.g., B. anthracis) and Clostridium (e.g., C. botulinum, C. tetani).

What is the total sequence of a given organism called?

Genome

What determines all inherited traits of an organism?

The genome

What are the four DNA bases?

A, T, C, G

What is a plasmid?

A small circular piece of extrachromosomal DNA

What is the significance of plasmids in bacteria?

They encode helpful genes such as antibiotic resistance.

Describe the process of DNA replication.

It is bidirectional and semiconservative.

What are the three stages of DNA replication?

Initiation, Elongation, Termination.

What occurs during the initiation stage of DNA replication?

Unwinding of the helix, priming, and loading DNA polymerase.

What happens during the elongation stage of DNA replication?

Sequential extension of DNA by adding nucleotides and proofreading.

What is the role of DNA gyrase in DNA replication?

It supercoils DNA after replication.

What is transcription?

The synthesis of an RNA copy of a gene.

What is the final product of most genes in bacteria?

Messenger RNA (mRNA).

What do codons in mRNA specify?

Amino acids.

How many codons are in the genetic code?

64 codons.

What is the start codon for translation?

AUG, which specifies methionine.

What are the stop codons in mRNA?

UGA, UAA, UAG.