Chapter 5: A Survey of Eukaryotic Cells and Microorganisms

Vocabulary flashcards covering eukaryotic cell structures, organelles, fungal morphology and classification, protists, and parasitic helminths.

Endosymbiotic Theory

The theory that eukaryotic cells evolved when a larger prokaryotic cell engulfed smaller prokaryotic cells.

Nucleus

A compact sphere that serves as the genetic center and repository of DNA, and is the most prominent organelle in a eukaryotic cell.

Nucleolus

A dark area within the nucleus responsible for ribosomal RNA (rRNA) synthesis and ribosome assembly.

Rough Endoplasmic Reticulum (RER)

A network of membranes originating from the nuclear envelope, appearing rough due to ribosomes, and functioning in protein synthesis and transport.

Smooth Endoplasmic Reticulum (SER)

A closed tubular network without ribosomes that functions in nutrient processing and the synthesis and storage of lipids.

Golgi apparatus

An organelle consisting of a stack of flattened sacs that modifies, stores, and packages proteins prior to secretion.

Cisternae

The stack of flattened sacs that make up the structure of the Golgi apparatus.

Lysosomes

Vesicles originating from the Golgi apparatus containing enzymes involved in intracellular digestion and protection against microbes.

Vacuoles

Membrane-bound sacs used for temporary storage, transport, digestion, and the regulation of osmotic pressure.

Phagosomes

Vacuoles formed by the merger of a food vacuole with a lysosome.

Mitochondria

Organelles responsible for energy production and storage (ATP) through the Krebs cycle and electron transport.

Cristae

The folds of the inner mitochondrial membrane that hold the enzymes and electron carriers of aerobic respiration.

Mitochondrial Matrix

The spaces around the cristae that contain DNA and prokaryotic ribosomes.

Chloroplasts

Organelles found in algae and plant cells that convert sunlight into chemical energy through photosynthesis.

Thylakoids

Sacs within the inner membrane of chloroplasts that are stacked into grana and carry pigments.

Grana

Stacks of thylakoids found within chloroplasts.

Ribosomes

Structures composed of rRNA and proteins that function in protein synthesis; they are larger in eukaryotes than in prokaryotes.

Cytoskeleton

A flexible framework of microfilaments and microtubules that provides structural support and anchors organelles.

Eukaryotic Flagella

Long, sheathed cylinders containing microtubules in a $9+2$ arrangement that are $10\times$ thicker than prokaryotic flagella.

Cilia

Short, numerous locomotor structures found only in certain protozoa and animal cells, used for motility, feeding, and filtering.

Glycocalyx

An outermost boundary composed of polysaccharides that functions in adherence, protection, and signal reception.

Sterols

Components of the eukaryotic cell membrane that confer stability to the phospholipid bilayer.

Mycoses

The general term for fungal infections in humans and other organisms.

Saprobes

Fungi that live as harmless organisms off dead plants and animals in their environment.

Hyphae

Long, threadlike cells that make up the bodies of filamentous fungi, also known as molds.

Mycelium

The woven, intertwining mass of hyphae that constitutes the body of a mold.

Septa

Cross walls that may divide hyphae into separate cell compartments.

Yeasts

Microscopic fungi with a round to oval shape that reproduce asexually by budding.

Budding

The asexual reproductive process in yeast where swellings grow on the surface and become separate cells.

Pseudohypha

A chain of yeasts formed when buds remain attached in a row rather than separating.

Dimorphic

A characteristic of some pathogenic molds where they can exist in either hyphae or yeast forms.

Sporangiospores

Asexual spores formed by successive cleavages within a saclike head called a sporangium.

Conidiospores

Free asexual spores, also called conidia, that are not enclosed by a spore-bearing sac.

Zygospores

Sexual spores formed following the fusion of two different strains and the maturation of a sexual structure.

Ascospores

Sexual spores produced in a saclike structure called an ascus.

Basidiospores

Sexual spores formed on the outside of a club-shaped structure called a basidium.

Phylum Zygomycota

Fungal group characterized by zygospores and usually nonseptate hyphae.

Phylum Ascomycota

The largest fungal phylum, where members produce ascospores in asci and have hyphae with porous septa.

Phylum Basidiomycota

Fungal group including mushrooms and puffballs that reproduce sexually using basidia and basidiospores.

Phylum Chytridimycota

Primitive fungi that do not typically form hyphae and are characterized by flagellated spores called zoospores.

Algae

Eukaryotic, photosynthetic organisms that are usually unicellular or colonial and contain chlorophyll a.

Plankton

Free-living algae that inhabit fresh and marine water and provide the basis of the aquatic food web.

Protozoa

A diverse group of unicellular eukaryotes that lack a cell wall and are typically heterotrophic.

Ectoplasm

The clear outer layer of protozoan cytoplasm involved in locomotion, feeding, and protection.

Endoplasm

The granular inner region of protozoan cytoplasm that houses the nucleus and organelles.

Trophozoite

The motile, active feeding stage of the protozoan life cycle.

Cyst

A dormant, resting stage that many protozoa enter during unfavorable conditions for growth and feeding.

Trypanosoma brucei

A pathogenic flagellate that causes African sleeping sickness and is transmitted by blood-sucking vectors.

Entamoeba histolytica

An infective amoeba that causes amebic dysentery following the ingestion of its cysts.

Nematodes

Commonly known as roundworms, these helminths have a complete digestive tract and a protective surface cuticle.