Microbiology: Chapter 05 - Eukaryotic Cells and Microorganisms

Comprehensive vocabulary flashcards covering Chapter 05: Eukaryotic Cells and Microorganisms from Microbiology: A Systems Approach (7th Edition).

Last Common Ancestor (LCA)

The precursor cell from which bacteria, archaea, and eukarya separately evolved approximately $4\text{ billion}$ years ago.

Endosymbiosis

The process by which bacterial or archaeal cells parasitized or were engulfed by other LCA descendants, eventually becoming permanent eukaryotic organelles such as mitochondria and chloroplasts.

Protozoa

A group of eukaryotic microorganisms that are always unicellular.

Fungi

Eukaryotic microorganisms that may be unicellular (yeasts) or multicellular (molds).

Algae

Photosynthetic eukaryotic organisms that may be unicellular or multicellular.

Helminths

Eukaryotic parasites that are always multicellular in their adult stage, though they have unicellular egg or larval forms.

Tissues

Groups of specialized cells that perform a particular function in a multicellular organism.

Organs

Structures composed of groups of tissues operating together to perform specific body functions.

Endosymbiotic Evidence

Characteristics shared by mitochondria/chloroplasts and bacteria, including their own circular DNA, $70\text{S}$ ribosomes, and two-layer membranes.

Eukaryote Evolution Timeline

Timeline showing LCA existence at approx. $4.6\text{ billion}$ years ago, individual DNA cells at approx. $4.3\text{ billion}$ years ago, and early eukaryotes at approx. $2.8\text{ billion}$ years ago.

Eukaryotic Flagella

Long, sheathed cylinders containing regularly spaced hollow microtubules in a $9 + 2$ arrangement; structurally more complex and $10\times$ thicker than bacterial flagella.

9 + 2 Arrangement

The structural configuration of microtubules in eukaryotic flagella and cilia, consisting of nine outer pairs surrounding two central microtubules.

Cilia

Short, numerous locomotor appendages found only in a single group of protozoa and certain animal cells, moving in an oarlike rowing motion.

Glycocalyx

An outermost polysaccharide extracellular matrix coming into direct contact with the environment, appearing as a network of fibers, slime layer, or capsule.

Fungal Cell Wall

A rigid outer layer providing structural support and shape, composed chemically of chitin or cellulose.

Cytoplasmic Membrane

A typical bilayer of phospholipids embedded with proteins and sterols that acts as a selectively permeable barrier.

Sterols

Rigid lipid molecules embedded in eukaryotic cytoplasmic membranes that serve to stabilize membrane structure.

Eukaryotic Structures Found in ALL Eukaryotes

Cytoplasmic membrane, nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, vacuoles, cytoskeleton, and glycocalyx.

Eukaryotic Structures Found in SOME Eukaryotes

Cell wall, locomotor appendages (flagella or cilia), and chloroplasts.

Flagellar Motion

A whipping motion exhibited by eukaryotic flagella during cell locomotion.

Ciliary Motion

An oarlike rowing motion used by cilia for locomotion, feeding, or filtering.

Extracellular Matrix

Another term for the eukaryotic glycocalyx boundary layer.

Cellulose

A structural polysaccharide component present in the cell walls of algae and some fungi.

Chitin

A tough polysaccharide constituent found in the cell walls of fungi.

Nucleus

A compact sphere separated from the cytoplasm by the nuclear envelope, serving as the primary control center of the eukaryotic cell.

Nuclear Envelope

A double membrane structure perforated with nuclear pores that separates the nucleus from the cytoplasm.

Nucleolus

A dense region within the nucleus that stains intensely due to its RNA content; the site for ribosomal RNA (rRNA) synthesis.

Chromatin

The genetic material of eukaryotic chromosomes composed of long, linear DNA molecules bound to histone proteins.

Histones

Proteins bound to DNA molecules that help condense and structure chromatin in eukaryotic nuclei.

Mitosis

Somatic eukaryotic cell division in which duplicated chromosomes are separated into two identical daughter nuclei.

Meiosis

The specialized cell division process responsible for the production of sex cells (gametes).

Endoplasmic Reticulum (ER)

A microscopic series of membrane-bound tunnels used in cellular transport and storage.

Rough Endoplasmic Reticulum (RER)

A continuous membrane network studded with ribosomes on its outer surface, where synthesized proteins are held for packaging and transport.

Smooth Endoplasmic Reticulum (SER)

A closed tubular network without ribosomes involved in the synthesis and storage of nonprotein molecules like lipids.

Golgi Apparatus

An organelle consisting of a stack of flattened, disc-shaped sacs (cisternae) where proteins are modified, packaged, and sorted.

Transitional Vesicles

Membrane-bound packets formed by the ER that transport newly synthesized proteins to the Golgi apparatus.

Condensing Vesicles

Vesicles pinched off by the Golgi apparatus containing modified proteins to be conveyed to lysosomes or secreted via exocytosis.

Lysosomes

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

Vacuoles

Membrane-bound sacs containing fluids or solid particles to be digested, excreted, or stored.

Phagosome

A membrane-bound structure formed around a food particle or microbe during engulfment.

Phagolysosome

A digestive vacuole created by the merger of a phagosome with a lysosome.

Cristae

Folds on the inner mitochondrial membrane that hold the enzymes and electron carriers of aerobic respiration.

Mitochondrial Matrix

The fluid space inside the inner membrane of a mitochondrion holding ribosomes, circular DNA, and metabolic enzymes.

Chloroplasts

Photosynthetic organelles capable of converting sunlight energy into chemical energy through photosynthesis.

Thylakoids

Disc-like photosynthetic membranes folded inside chloroplasts stacked into grana.

Granum

A stack of thylakoids located inside a chloroplast.

Stroma Matrix

The fluid surrounding the thylakoid stacks within the chloroplast envelope containing $70\text{S}$ ribosomes and DNA.

80S Ribosomes

Full-size eukaryotic ribosomes composed of a $60\text{S}$ large subunit and a $40\text{S}$ small subunit.

Polyribosomes

Short chains of ribosomes actively translating mRNA simultaneously.

Cytoskeleton

A dynamic intracellular network of actin filaments, intermediate filaments, and microtubules that anchors organelles, enables cell movement, and maintains cell shape.

Actin Filaments

Long thin protein strands of the cytoskeleton responsible for cellular movements such as contraction, crawling, and pinching.

Intermediate Filaments

Rope-like structural proteins of the cytoskeleton that reinforce cellular structure and structural support to organelles.

Microtubules

Long, hollow tubes of the cytoskeleton that maintain cell shape, transport organelles, and form cilia, flagella, and spindle fibers.

Macroscopic Fungi

Large visible fungi including mushrooms, puffballs, and gill fungi.

Microscopic Fungi

Microscopic fungal forms including molds and yeasts.

Yeast Cell

A unicellular fungal form with a round to oval shape that reproduces asexually by budding.

Hyphae

Long, threadlike cells that comprise the filaments of microscopic molds.

Pseudohypha

A chain of yeast cells formed when individual buds remain attached in a sequence.

Dimorphic Fungi

Fungal species capable of growing either as yeasts or hyphae depending on growth conditions such as temperature.

Heterotrophic

Nutritional mode of organisms that require organic substrates to obtain their necessary nutrients.

Saprobes

Organisms that obtain substrates and nutrition from dead plants and animals.

Parasites (Fungal)

Fungi that live on or in the living tissues of plant or animal hosts to derive nutrients.

Mycelium

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

Septa

Cross walls dividing fungal hyphae into distinct individual segments.

Septate Hyphae

Hyphae divided into cell-like compartments by internal cross walls called septa, as seen in Penicillium.

Nonseptate Hyphae

Continuous, multinucleated hyphal filaments lacking cross walls (septa), as seen in Rhizopus.

Vegetative Hyphae

Hyphae that grow into and penetrate the substrate to digest and absorb nutrients.

Reproductive Hyphae

Aerial hyphae that branch off the mycelium and produce fungal spores.

Sporangiospores

Asexual spores formed by successive cleavages within a sac-like head called a sporangium.

Conidiospores (Conidia)

Free asexual fungal spores not enclosed within a spore-bearing sac.

Sporangium

A closed sac-like structure borne on a stalk (sporangiophore) in which sporangiospores develop.

Community-Acquired Fungal Infections

Environmental fungal infections affecting the general population, such as Histoplasmosis and Coccidioidomycosis.

Opportunistic Fungal Infections

Infections caused by environmental or normal biota fungi (e.g. Candidiasis, Mucormycosis) that infect individuals with weakened immune systems.

Hospital-Associated Fungal Infections

Fungal infections contracted in clinical settings by hospitalized or long-term care patients.

Mycoses

Infectious diseases in humans or animals caused by fungal pathogens.

Protist

Any eukaryotic unicellular or colonial organism that lacks true tissues.

Plankton

A floating community of microscopic aquatic organisms that forms the base of the web and generates approx. $70\%$ of Earth's oxygen.

Trophozoite

The active, motile, feeding stage of a protozoan requiring ample food and moisture.

Cyst

The dormant, resting stage formed by protozoa when growth conditions become unfavorable.

Encystment

The process in which a protozoan trophozoite rounds up, loses motility, and secretes a tough protective wall.

Excystment

The breaking open of a protozoan cyst wall when moisture and nutrients are restored, reactivating the trophozoite.

Conjugation

A form of sexual genetic exchange between two protozoan cells.

Pseudopods

Temporary blunt extensions of cytoplasm ("false feet") used by amoebas for locomotion and feeding.

Ectoplasm

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

Endoplasm

Granular inner region of protozoan cytoplasm containing the nucleus, mitochondria, and vacuoles.

Amoeboid Protozoa

Protozoa moving via pseudopods, including Entamoeba histolytica, Naegleria, and Acanthamoeba.

Flagellated Protozoa

Protozoa propelled by flagella, including Giardia lamblia, Trichomonas vaginalis, Trypanosoma species, and Leishmania species.

Ciliated Protozoa

Protozoa that move using cilia distributed across the cell surface, such as Balantidium coli.

Sporozoa (Nonmotile Protozoa)

Parasitic protozoa that lack motility structures in their adult stage, such as Plasmodium falciparum and Toxoplasma gondii.

Helminths

Multicellular parasitic worms including roundworms, tapeworms, and flukes.

Flatworms (Platyhelminthes)

Helminths with thin, segmented body plans, divided into cestodes and trematodes.

Roundworms (Nematodes)

Helminths with long, unsegmented, cylindrical bodies, such as Ascaris lumbricoides and Enterobius vermicularis.

Cestodes

Ribbon-like flatworms commonly called tapeworms.

Trematodes

Flatworms with flat, ovoid bodies commonly referred to as flukes.

Intermediate (Secondary) Host

The host organism in which helminth larval development occurs.

Definitive (Final) Host

The host organism in which adult helminths mate and reproduce sexually.

Hermaphroditic

Describing an organism possessing both male and female reproductive organs in the same individual.

Enterobius vermicularis

The pinworm, a roundworm causing an uncomplicated infestation of the large intestine in humans.

Cuticle

A thick, protective outer layer covering helminths that shields them from host digestive enzymes.

Scolex

The head attachment structure of a tapeworm featuring suckers or hooks.