Eukaryotic Cells and Microorganisms Flashcards

This set of vocabulary flashcards covers the major concepts of eukaryotic cell biology, the history of eukaryotes, and the classifications of fungi, protozoa, and helminths as presented in Chapter 4.

Last Common Ancestor (LCA)

A likely large organism with loose boundaries and RNA as genetic material from which bacteria, archaea, and eukarya evolved approximately $3$ to $4$ billion years ago.

Endosymbiosis

The evolutionary process where pre-eukaryotic cells engulfed bacteria, which subsequently became specialized organelles like mitochondria or chloroplasts.

Eukaryotic Flagella

Long, sheathed cylinders containing regularly spaced microtubules that are approximately $10$ times thicker than bacterial flagella.

Cilia

Short, numerous locomotor structures similar in structure to flagella but found only in a single group of protozoa and certain animal cells.

Glycocalyx

An outermost layer of polysaccharides that appears as a network of fibers, a slime layer, or a capsule, providing protection and adherence.

Fungal Cell Wall

A rigid boundary structure containing a thick inner layer of polysaccharide fibers made of chitin or cellulose and a thin outer layer of mixed glycans.

Sterols

Various rigid molecules embedded in the cell membrane that provide stability, particularly important for cells lacking a cell wall.

Nuclear Envelope

An external boundary of the nucleus composed of two parallel membranes perforated with pores that allow macromolecule migration.

Nucleolus

A region within the nucleoplasm responsible for ribosomal RNA synthesis and the collection of ribosomal subunits.

Chromatin

The genetic material of the cell, composed of linear DNA and histone proteins.

Rough Endoplasmic Reticulum (RER)

A series of membrane tunnels with attached ribosomes used for protein synthesis and transport from the nucleus to the cytoplasm.

Smooth Endoplasmic Reticulum (SER)

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

Golgi Apparatus

An organelle consisting of flattened sacs called cisternae where proteins are chemically modified and packaged into vesicles.

Lysosomes

Vesicles containing a variety of enzymes for intracellular digestion of food particles and protection against microorganisms.

Mitochondria

Organelles that generate ATP, containing circular DNA, $70S$ ribosomes, and folds called cristae.

Cristae

Folds on the inner membrane of mitochondria that house the enzymes and electron carriers required for aerobic respiration.

Chloroplasts

Organelles in plants and algae that convert sunlight into chemical energy through photosynthesis, producing oxygen as a by-product.

Eukaryotic Ribosome

A protein-synthesizing structure with a size of $80S$, consisting of a $60S$ and a $40S$ subunit.

Cytoskeleton

A framework comprising actin filaments, intermediate filaments, and microtubules that anchors organelles and facilitates cell movement.

Hyphae

Long, threadlike cells that make up the bodies of filamentous fungi or molds.

Dimorphic

The ability of some fungal cells to take either yeast or hyphae forms depending on growth conditions.

Saprobic

A nutritional strategy in which organisms obtain nutrients from the remnants of dead plants and animals.

Mycelium

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

Sporangiospores

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

Conidiospores

Asexual fungal spores, also known as conidia, that are free and not enclosed by a spore-bearing sac.

Trophozoite

The motile, active feeding stage of a protozoan's life cycle that requires ample food and moisture.

Cyst

A dormant, resistant stage of a protozoan that allows survival in unfavorable environmental conditions and aids in disease spread.

Conjugation

A form of sexual reproduction in ciliates where two cells fuse to exchange micronuclei, resulting in genetic variation.

Nematodes

Roundworms characterized by an elongated, cylindrical, and unsegmented body plan.

Cestodes

A group of flatworms, commonly known as tapeworms, featuring a thin and often segmented body plan.

Definitive Host

The host organism in which a helminth reaches adulthood and undergoes sexual reproduction.

Intermediate Host

The host organism in which helminth larval development occurs before reaching maturity.