Microbial Life: Prokaryotes

Flashcards about Prokaryotes

How long ago did prokaryotes first appear on Earth?

Approximately 3.5 billion years ago.

What are three things that prokaryotes do?

Recycle nutrients, fix nitrogen and are pioneers of new environments.

What type of organisms were the first ancient prokaryotes, in terms of obtaining nutrition?

Chemoautotrophs

What is the name of the blue-green algae that evolved from first terrestrial prokaryotes?

Cyanobacteria

What are three differences between prokaryotes and eukaryotes?

Prokaryotes have no membrane-bound organelles, no mitosis or meiosis, and one circular double stranded DNA chromosome.

What are plasmids?

Small circular DNA molecules found in prokaryotes, which replicate independently of the bacteria’s own chromosome.

What are the two Domains of Prokaryotes?

Archaea and Bacteria

Is peptidoglycan found in archaea cell walls?

No. Archaea do NOT have peptidoglycan in their cell walls. They have polysaccharides instead.

What is the key difference between Gram-positive and Gram-negative bacteria?

Gram-positive bacteria have a thick cell wall composed of 90% peptidoglycan, while Gram-negative bacteria have a thin cell wall (10% peptidoglycan) and an outer layer of lipopolysaccharide and lipoproteins.

What are the three main shapes of prokaryotes?

Coccus (spherical), Bacillus (rod), and Spirillus (spiral).

How do bacteria reproduce?

Asexually through binary fission, which results in clones.

Name three types of genetic recombination in bacteria.

Transformation, Transduction, and Conjugation

What happens during bacterial transformation?

Bacteria absorbs plasmid or bacterial DNA shed by another bacteria

What is bacterial transduction?

Bacteriophages move bacterial DNA from one bacteria to another.

What is bacterial conjugation?

DNA is transferred from one bacteria to another through the pilus.

What is the difference between an epidemic, a pandemic, and an endemic?

An epidemic affects a high percentage of the population in a specific area, a pandemic is a widespread, worldwide epidemic, and an endemic is a disease that is always present in a population.

How does antibiotic resistance develop in bacteria?

Through natural selection: bacteria exposed to antibiotics, the resistant ones survive and reproduce. Also, transformation, transduction, and conjugation allow bacteria to obtain resistant genes.

What is MRSA?

Methicillin-resistant Staphylococcus aureus, a common bacteria that has become resistant to most antibiotics due to overuse of antibiotics.