The Prokaryotes: Eubacteria and Archaea

Flashcards covering key vocabulary, structures, functions, and classifications of Prokaryotes, including Eubacteria and Archaea, based on the provided lecture notes.

Prokaryotes

Smallest organisms on Earth (most are 1-2 μm long), lack organelles and a nucleus but all have a cell wall. They live in every imaginable habitat.

Eubacteria

One of the two major groups of prokaryotes, sometimes just called bacteria, genetically very different from Archaea.

Archaea

One of the two major groups of prokaryotes, historically called Archaebacteria, genetically very different from Eubacteria. Their cell walls do not contain peptidoglycan, and they often inhabit extreme environments.

Pathogenic Prokaryotes

Prokaryotes that are harmful to humans, livestock, and crops, causing diseases such as tuberculosis, strep throat, cholera, and typhoid fever.

Helpful Prokaryotes

Prokaryotes that support the production of food items like bread, cheese, yogurt, produce antibiotics, can be engineered to produce compounds like insulin, produce vitamin K and B12 in the large intestine, and play key roles as decomposers, producers, and nitrogen fixers in ecosystems.

Nitrogen Fixing Bacteria

Prokaryotes that play an important role in ecosystems by converting atmospheric nitrogen to a usable form for plants.

Cyanobacteria

Photosynthetic bacteria, also known as blue-green algae, that play major roles as producers and nitrogen fixers in aquatic ecosystems and are major producers of atmospheric oxygen.

Proteobacteria

A major group of bacteria, some are photosynthetic, ancient forms were likely ancestors of eukaryotic mitochondria, some are nitrogen fixing, and they are responsible for many diseases.

Gram-positive bacteria

A major group of bacteria that cause many diseases (e.g., anthrax, strep throat), are used in food production (e.g., lactobacillus in yogurt), and some have lost their cell wall.

Spirochetes

A major group of spiral-shaped bacteria with a flagellum embedded in their cytoplasm, moving with a corkscrew motion, and causing diseases like syphilis.

Chlamydias

A major group of bacteria that are all parasites living within other cells, causing infections like chlamydia (a common STI) and trachoma (leading cause of blindness).

Plasmid

A small loop of DNA in bacteria that carries genes, often providing an advantage to the cell (e.g., antibiotic resistance).

Peptidoglycan

A protective coating found ONLY on bacteria, making up its cell wall, used to identify different types of bacteria and is a target for antibiotics.

Outer Capsule

An additional protective layer some bacteria have that reduces water loss and resists high temperatures, antibiotics, and viruses.

Flagella

Whip-like hairs used by bacteria for movement.

Pili

Stiff proteins on bacteria that help cells attach to one another.

Coccus

A spherical shape of bacteria.

Bacillus

A rod shape of bacteria.

Spirillum

A spiral shape of bacteria, less common than coccus or bacillus.

Autotrophs (Bacteria)

Bacteria that make their own food from inorganic chemicals (e.g., carbon dioxide, minerals).

Heterotrophs (Bacteria)

Bacteria that get nutrients from carbon-containing organic chemicals found in living or dead organisms.

Obligate Aerobes

Bacteria that need oxygen to survive.

Obligate Anaerobes

Bacteria that are killed by oxygen.

Facultative Anaerobes

Bacteria that can use oxygen when it is present (aerobic respiration) but can also live anaerobically (through fermentation) when oxygen is absent.

Binary Fission

The asexual reproduction method of bacteria where DNA is replicated, and the parent cell splits into two daughter cells, each with an exact copy of the genetic material.

Conjugation

A form of sexual reproduction in bacteria where one cell passes a copy of a plasmid to another nearby cell through a hollow pilus, exchanging genetic information.

Horizontal Gene Transfer

The process where new DNA from a different species is acquired by a bacterial cell, often through conjugation.

Transformation

A way for bacteria to increase genetic diversity by taking in pieces of DNA directly from the environment.

Transduction

A way for bacteria to gain genetic diversity by being infected with a virus, which carries bacterial DNA from one cell to another.

Endospores

Dormant structures formed by some bacteria to protect their DNA when environmental conditions are unfavorable, allowing them to survive for thousands of years.

Gram Staining

A technique used to identify different types of bacteria based on their cell wall composition, distinguishing Gram-positive (purple) from Gram-negative (pink) bacteria.

Gram Positive Bacteria (Stain)

When stained, these bacteria appear purple because their thick layers of peptidoglycan pick up the stain; they lack an outer membrane.

Gram Negative Bacteria (Stain)

When stained, these bacteria appear pink because they have an outer membrane and only a small layer of peptidoglycan, which does not retain the primary stain as well.

Endotoxins

Poisons produced by Gram-negative bacteria, which are lipid portions of their lipopolysaccharides (LPS) released when the bacteria die and their cell wall breaks apart.

Exotoxins

Poisons (proteins) produced inside pathogenic bacteria, most commonly Gram-positive, as part of their growth and metabolism, which are then secreted or released into the surrounding medium.

Antibiotics

Medications that combat bacteria by interfering with the peptidoglycan in their cell wall, among other mechanisms.

Antibiotic Resistance

The phenomenon where bacteria evolve to become less susceptible or immune to antibiotics, often due to overuse of these drugs leading to the survival and reproduction of resistant strains.

Methanogens

A type of Archaea that converts hydrogen and carbon dioxide into methane for energy, are obligate anaerobes, and are found in places like animal guts, swamps, and wetlands.

Halophiles

A type of Archaea that are 'salt-loving,' growing in very salty conditions (e.g., Dead Sea, salted foods), mostly aerobic, and get energy from organic food molecules or use light as a secondary source.

Thermophiles

A type of Archaea that are 'heat-loving,' living at very high temperatures (e.g., ocean hydrothermal vents, hot springs) with optimal growth between 70°C and 85°C.

Psychrophiles

A type of Archaea that are 'cold-loving,' found mostly in Antarctic and Arctic oceans, with an optimal temperature range of -10°C to -20°C.