General Biology: Evolution, Microorganisms, Fungi, and Protists

Vocabulary flashcards covering prokaryotes, viruses, evolutionary mechanisms, evidence for common descent, fungal biology and phyla, and protist diversity and pathology.

Extremophile

A prokaryote adapted to thrive under extreme environmental conditions, such as high temperatures, freezing environments, very low oxygen, high radiation, or hypersaline conditions.

Peptidoglycan

A polymer consisting of polysaccharides cross-linked by peptides that forms the bacterial cell wall; it is absent in the cell walls of Archaea.

Binary Fission

The asexual reproductive process used by prokaryotes in which a single cell divides into two genetically identical daughter cells.

Cocci, Bacilli, and Spirilli

The three primary morphological shapes of prokaryotes, referring to spherical cells, rod-shaped cells, and spiral-shaped cells, respectively.

Zoonotic Disease

An infectious disease that primarily infects animals and is transmitted to humans, accounting for about $75\%$ of emerging infectious diseases in humans.

Biofilm

A microbial colony that adheres to surfaces (such as vegetable leaves, meat, or processing equipment) and is responsible for many foodborne illnesses.

MRSA (Methicillin-Resistant Staphylococcus aureus)

A dangerous strain of a common bacterium that has evolved resistance to multiple commonly used antibiotics and can cause severe infections in the skin, lungs, urinary tract, and bloodstream.

Virion

A single, complete, and infectious viral particle outside a host cell.

Capsid

The outer protein coat of a virus that encloses and protects its DNA or RNA genome.

Latent Viral Infection

A viral infection in which the virus remains dormant within host cells or integrated into host DNA for long periods without causing active symptoms until reactivated.

Oncogenic Virus

A cancer-causing virus (such as Human Papillomavirus / HPV) whose genetic material can insert into host DNA and cause cellular mutations.

Viroid

An infectious plant pathogen consisting solely of a small, single-stranded circular RNA particle lacking a protein coat.

Prion

An infectious, misfolded protein lacking nucleic acids that induces normal cellular proteins in nervous tissue to misfold and aggregate, causing fatal neurodegenerative diseases.

Biological Evolution

A change in the genetic characteristics of a population of organisms over time, resulting in descent with modification from common ancestors.

Microevolution

Small-scale evolutionary changes in allele frequencies that occur within a single species or population.

Macroevolution

Large-scale evolutionary changes that occur at or above the level of the species, resulting in the origin of new genera or higher taxonomic groups.

Natural Selection

The nonrandom mechanism of evolution in which individuals with favorable, inheritable traits survive and reproduce at higher rates, increasing those traits in subsequent generations.

Genetic Drift

A random mechanism of evolution caused by chance events that alter allele frequencies in a population, producing more pronounced effects in smaller populations.

Bottleneck Effect

A form of genetic drift resulting from a catastrophic event that drastically reduces population size, leaving survivors with an unrepresentative sample of original genetic diversity.

Founder Effect

A type of genetic drift that occurs when a small group of individuals separates from a larger parent population to establish a new population with only a subset of the original gene pool.

Gene Flow

The exchange of alleles between two different populations via the migration and interbreeding of individuals.

Sexual Selection

A form of natural selection where nonrandom mate choice, typically driven by female preferences, leads to the evolution of elaborate male displays, ornaments, or armaments.

Adaptation

An inherited, population-level trait shaped over generations by natural selection that enhances the survival and reproductive fitness of an organism.

Homologous Structures

Anatomical features in different organisms that share a similar underlying skeletal architecture because they were inherited from a common ancestor, regardless of functional differences.

Analogous Structures

Anatomical structures in different species that serve similar functions but evolved independently through convergent evolution rather than via shared ancestry.

Transitional Form

Fossilized remains of organisms displaying intermediate anatomical traits between ancestral lineages and their derived descendants (such as synapsids or Pakicetus).

Human Chromosome 2

A chromosome formed by the telomeric fusion of two ancestral primate chromosomes, proven by the presence of internal telomeric sequences and an inactivated second centromere.

Vestigial Structure

A reduced anatomical structure or inactive pseudogene that had an important function in an organism's ancestors but is nonfunctional or diminished in modern descendants.

Mycology

The specialized biological study of fungi.

Hyphae

The branching, thread-like filaments that constitute the vegetative feeding structures and multicellular body of a fungus.

Mycelium

A dense, root-like underground mass formed by a network of interconnected fungal hyphae.

Chitin

A tough, structural polysaccharide found in fungal cell walls that provides rigid support and protects the organism from desiccation.

Exoenzymes

Digestive enzymes secreted by fungal hyphae directly into the environment to break down organic matter externally before nutrients are absorbed.

Plasmogamy

The initial sexual stage in fungi wherein the haploid cytoplasms of two distinct mycelia fuse without nuclear fusion, creating a heterokaryotic cell.

Karyogamy

The sexual stage in fungi during which two haploid nuclei in a heterokaryotic cell fuse to create a diploid ($2n$) zygote.

Chytridiomycetes (Chytrids)

The most primitive fungal phylum, consisting of mostly aquatic fungi that produce motile flagellated spores and are responsible for worldwide amphibian die-offs.

Basidiomycetes (Club Fungi)

A fungal phylum including mushrooms, shelf fungi, smuts, and rusts that bear sexual spores externally on club-shaped structures called basidia.

Ascomycetes (Sac Fungi)

A diverse fungal phylum including yeasts, morels, and truffles that produces sexual spores internally within microscopic sac-like structures called asci.

Zygomycetes

A fungal phylum consisting largely of bread molds (such as Rhizopus) and insect parasites that reproduce sexually by producing specialized zygotes.

Glomeromycetes

A phylum of obligate mutualistic fungi that colonize plant roots to form mycorrhizae with $80\%$ to $90\%$ of all land plant species.

Mycosis

A disease or tissue infection caused by a fungal pathogen in humans or animals, such as ringworm, athlete's foot, or Valley fever.

Pseudopodia, Cilia, and Flagella

The three specialized locomotor extensions used by motile protists, consisting of cytoplasmic projections, short hair-like extensions, and long whip-like organelles, respectively.

Phytoplankton

Microscopic, single-celled photosynthetic protists drifting in the upper illuminated layers of marine and freshwater ecosystems that serve as the base of aquatic food chains.

Plasmodium

A genus of parasitic protists transmitted by mosquitoes that invades human liver and red blood cells, causing malaria.

Trypanosoma

A genus of flagellated protozoan parasites inhabiting human blood that causes African sleeping sickness and Chagas disease.