Unit 1f. Prokaryotes

Where can prokaryotes thrive?

Prokaryotes can thrive in extreme environments, including acidic, salty, cold, or hot places.

What are the two domains of prokaryotes?

Bacteria and Archaea.

What is the size range of prokaryotic cells?

0.5 to 5 μm.

What are the three most common shapes of prokaryotes?

Spheres (cocci), rods (bacilli), and spirals (spirilli).

What is a key feature of nearly all prokaryotic cells?

Their cell wall.

What is peptidoglycan?

A network of sugar polymers cross-linked by polypeptides found in bacterial cell walls.

How do Gram-positive and Gram-negative bacteria differ?

Gram-positive bacteria have simpler walls with more peptidoglycan, while Gram-negative bacteria have less peptidoglycan and an outer membrane.

Why are Gram-negative bacteria more likely to be antibiotic resistant?

Because of their outer membrane that can be toxic and protect them from antibiotics.

What are fimbriae?

Hair-like appendages that allow prokaryotes to stick to substrates or other individuals.

What is the function of pili in prokaryotes?

They allow for the exchange of DNA between prokaryotic cells.

What is taxis in bacteria?

The ability to move toward or away from a stimulus.

What is the most common structure used by prokaryotes for movement?

Flagella.

What is the nucleoid region in prokaryotic cells?

The area where the circular chromosome is located, not surrounded by a membrane.

What are plasmids?

Smaller rings of DNA that replicate independently in some bacteria.

Three key features of prokaryotic reproduction:

Small, reproduce by binary fission, short generation times

Three factors contribute to genetic diversity:

Rapid reproduction (binary fission), mutation, genetic recombination

What is binary fission?

The method by which prokaryotes reproduce, dividing every 1-3 hours.

What is genetic recombination?

the combining of DNA from two sources

Movement of genes among individuals from different species is called?

horizontal gene transfer

What is transformation in prokaryotes?

The process where a prokaryotic cell takes up and incorporates foreign DNA from the environment.

What is transduction?

The movement of genes between bacteria by bacteriophages (viruses that infect bacteria).

What is conjugation in prokaryotes?

The process where genetic material is transferred between prokaryotic cells via a pilus.

What are phototrophs?

obtain energy from light.

What are chemotrophs?

obtain energy from chemicals

What are autotrophs?

require CO2 as a carbon source

What are heterotrophs?

require an organic nutrient to make organic compounds

What are obligate aerobes?

require O2 for cellular respiration

What are obligate ANaerobes?

poisoned by O2 and use fermentation or anaerobic respiration

Facultative anaerobes can…

survive with or without O2

What is nitrogen fixation?

The process by which some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3).

Halophiles live in

highly saline environments

Thermophiles thrive in

very hot environments

Methanogens live in

swamps and marshes and produce methane as a waste product

What is bioremediation?

The use of organisms to remove pollutants from the environment.

What role do prokaryotes play in chemical recycling?

They function as decomposers, breaking down dead organisms and waste products.