305 Biology chapter 23 Prokaryotes

Microfossils

Fossilized forms of microscopic life that provide evidence of early life on Earth, estimated to have begun over 3.5 billion years ago.

Prokaryotes

Unicellular organisms without membrane-bound organelles; the most abundant forms of life on Earth.

Archaea

A domain of prokaryotes discovered in the mid-1970s, distinct from bacteria, with unique structural features.

Binary fission

A method of asexual reproduction in prokaryotes where the cell divides into two identical cells.

Gram Stain

A technique used to classify bacteria into two main categories based on the structure of their cell walls: Gram-positive and Gram-negative.

Peptidoglycan

A polymer that forms a protective mesh-like structure in the cell wall of many bacteria, absent in archaeal cells.

Capsule

An outer covering of polysaccharides that protects bacterial cells from environmental threats.

Photosynthetic bacteria

Bacteria that produce glucose by photosynthesis, either oxygenic (producing oxygen) or anoxygenic (producing sulfur and sulfate).

Heterotrophs

Organisms that obtain carbon from other organisms; they depend on external sources for nutrients.

Autotrophs

Organisms that obtain carbon from carbon dioxide (CO2); they can produce their own food.

Pathogen

An organism that causes disease, including certain bacteria.

Antibiotic resistance

The ability of bacteria to survive and grow despite the presence of antibiotics, often due to genetic mutations and gene transfer.

Virion

A mature infectious virus particle consisting of nucleic acid and a protein coat.

Lytic Cycle

A viral reproduction cycle during which the virus takes over the host cell's machinery and often results in cell lysis.

Lysogenic Cycle

A viral reproduction cycle in which the virus integrates its DNA into the host's DNA and may remain dormant.

Endocytosis

A process by which viruses enter host cells by engulfing them within the host cell membrane.

Zoonotic spillover

The transmission of pathogens from animals to humans, accounting for a significant percentage of human diseases.

Antigenic drift

Minor changes in viral proteins due to mutations, leading to variations in the virus.

Pandemic conditions

Specific criteria that must be met for a new strain of virus to result in a widespread outbreak, including novel proteins and efficient transmission.

Zoonotic diseases

Diseases that are transmitted from animals to humans, often involving pathogens such as viruses, bacteria, or parasites.

Cyanobacteria

Photosynthetic bacteria often referred to as blue-green algae, important for oxygen production and nitrogen fixation.

Biofilms

Communities of microorganisms that adhere to surfaces, encased in a protective matrix, often found in natural and artificial environments.

Endospores

A resistant dormant structure formed by some bacteria, allowing survival in extreme conditions.

Viral replication

The process by which a virus reproduces and creates new virions within a host cell.

Bacteriophage

A type of virus that specifically infects and replicates within bacteria.

Chloroplasts

Membrane-bound organelles found in plants and algae where photosynthesis occurs.

Antiviral drugs

Medications used to treat viral infections by inhibiting viral replication.

R plasmids

Extrachromosomal DNA in bacteria that often carry genes for antibiotic resistance.

Mutagenesis

The process by which changes in the DNA sequence occur, leading to mutations.

Nutrient cycling

The process by which nutrients are exchanged in the ecosystem, involving decomposition, and nutrient uptake by plants.

Bioremediation

The use of microorganisms to clean up contaminated environments, such as oil spills or heavy metal pollution.

Symbiosis

A close and often long-term interaction between two different biological species, which can be mutualistic, commensal, or parasitic.

Pathogenic bacteria

Bacteria that can cause disease in humans, animals, and plants.

Plasmids

Small, circular DNA molecules found in bacteria that can replicate independently and often carry genes beneficial for survival.

Transduction

A process of horizontal gene transfer where bacterial DNA is transferred from one bacterium to another by a virus.

Conjugation

A method of genetic transfer between bacteria involving direct contact and transfer of genetic material through a pilus.

Antimicrobial peptides

Natural peptides produced by organisms that provide defense against pathogens by disrupting their membranes.

Phage therapy

A therapeutic approach that uses bacteriophages to target and kill specific bacterial infections.

Eutrophication

A process where water bodies become overly enriched with nutrients, leading to excessive growth of algae and depletion of oxygen.