eukaryotes

Eukarya

Domain of organisms characterized by larger cells, internal membranes, and membrane-bound organelles

Eukaryotic Compartmentalization

Separation of cellular processes into membrane-bound compartments for greater efficiency and control

Advantages of Compartmentalization

Independent regulation of cellular processes, efficient transport, and increased cellular complexity

Eukaryotic Plasma Membrane

Phospholipid bilayer containing sterols and sphingolipids that regulate fluidity and permeability

Sterols (Cholesterol)

Membrane components that help regulate membrane fluidity and stability

Sphingolipids

Membrane lipids involved in membrane structure and lipid raft formation

Lipid Rafts

Specialized membrane microdomains involved in cellular signaling and transport

Cellulose

Major structural component of plant and algal cell walls

Pectin

Cell wall polysaccharide found in plants and algae

Chitin

Major structural component of fungal cell walls and some protist cysts

Glucans

Polysaccharides found in fungal cell walls

Eukaryotic Cell Walls

May contain cellulose, pectin, chitin, or glucans but never peptidoglycan

Cytoskeleton

Network of protein filaments responsible for structural support, movement, intracellular transport, cytokinesis, and chromosome separation

Amoeboid Movement

Cell movement driven by cytoskeletal rearrangements

Endocytosis

Uptake of material through membrane engulfment; found only in eukaryotes

Cytokinesis

Division of the cytoplasm during cell division

Rough Endoplasmic Reticulum (Rough ER)

Site of protein synthesis

Smooth Endoplasmic Reticulum (Smooth ER)

Site of lipid synthesis

Golgi Apparatus

Organelle responsible for modification, packaging, and secretion of cellular products

Lysosomes

Digestive organelles containing hydrolytic enzymes, primarily found in animal cells

Hydrolytic Enzymes

Enzymes that break down biological molecules within lysosomes

Vacuoles

Organelles involved in storage, digestion, and osmoregulation

Nucleus

Membrane-bound organelle containing chromosomal DNA associated with histones

Histones

DNA-packaging proteins associated with eukaryotic chromosomes

Nuclear Envelope

Double membrane surrounding the nucleus

Nuclear Pores

Channels that regulate transport between the nucleus and cytoplasm

Nuclear Transport

Process involving mRNA export and protein import through nuclear pores

Eukaryotic Ribosomes

Larger ribosomes with a structure different from bacterial ribosomes

Mitochondria

Double-membraned organelles responsible for ATP production and cellular respiration

Cellular Respiration

Process of ATP generation carried out in mitochondria

TCA Cycle

Central metabolic pathway occurring in mitochondria

Electron Transport Chain

Series of reactions located on the inner mitochondrial membrane that generates ATP

Oxidative Phosphorylation

ATP production driven by electron transport and proton gradients

Mitochondrial DNA

Genetic material contained within mitochondria

Mitochondrial Ribosomes

Ribosomes located inside mitochondria

Mitochondrial Binary Fission

Method by which mitochondria replicate independently of the nucleus

Hydrogenosomes

Organelles in anaerobic protists that generate ATP through fermentation

Fermentation-Based ATP Production

ATP generation without oxygen, characteristic of hydrogenosomes

Chloroplasts

Photosynthetic organelles containing chlorophyll and carotenoids

Photosynthesis

Process converting CO₂, H₂O, and light into carbohydrates and O₂

Chlorophyll

Primary photosynthetic pigment in chloroplasts

Carotenoids

Accessory pigments involved in photosynthesis and photoprotection

Chloroplast DNA

Genetic material contained within chloroplasts

Chloroplast Ribosomes

Ribosomes located inside chloroplasts

Starch Granules

Storage structures commonly found in chloroplasts

Lipid Droplets

Lipid storage inclusions found in chloroplasts

Cilia

Short hair-like motility structures measuring approximately 5–20 µm

Eukaryotic Flagella

Long whip-like motility structures measuring approximately 100–200 µm

Dynein

Motor protein responsible for movement of cilia and flagella

ATP-Powered Motility

Mechanism by which eukaryotic cilia and flagella generate movement

Bacterial vs Eukaryotic Flagella

Bacterial flagella use proton motive force, whereas eukaryotic flagella use ATP-driven dynein motors

Endosymbiosis

Relationship in which one organism lives inside another

Endosymbiotic Theory

Hypothesis that mitochondria and chloroplasts originated from ancient bacteria that became permanent cellular residents

Mitochondrial Origin

Mitochondria evolved from aerobic bacteria

Chloroplast Origin

Chloroplasts evolved from cyanobacteria

Hydrogenosome Origin

Hydrogenosomes likely evolved from mitochondrial ancestors

Secondary Endosymbiosis

Process in which a eukaryote engulfs another photosynthetic eukaryote, producing photosynthetic protists

Protists

Diverse eukaryotes that generally require moisture and are commonly aquatic

Photoautotrophs

Protists that obtain energy through photosynthesis

Heterotrophs

Protists that obtain nutrients from external organic sources

Saprophytes

Organisms that absorb nutrients from dead organic matter through osmotrophy

Osmotrophy

Nutrient acquisition through absorption of dissolved organic compounds

Holozoic Nutrition

Feeding strategy involving phagocytosis of food particles

Mixotrophs

Organisms capable of both photosynthesis and heterotrophy

Plasmalemma

Cell membrane of a protist

Pellicle

Supportive layer beneath the cell membrane that provides shape and protection

Contractile Vacuole

Organelle responsible for osmoregulation and water removal

Secretory Vacuole

Organelle involved in secretion of substances

Phagocytic Vacuole

Organelle involved in digestion of engulfed food particles

Cytostome

Cell mouth used for phagocytosis

Cytoproct

Cell anus used for waste elimination

Encystment

Process of cyst formation

Excystment

Process by which an organism emerges from a cyst

Cyst

Resistant survival and transmission stage that protects against environmental stress

Functions of Cysts

Protection, reproduction, and transmission

Trophozoite

Active, feeding, and replicating stage of a protist

Binary Fission

Most common form of asexual reproduction in protists

Multiple Fission

Asexual reproduction producing multiple offspring simultaneously

Budding

Asexual reproduction involving growth of a new individual from the parent

Fragmentation

Asexual reproduction common in filamentous forms where fragments develop into new organisms

Gamont

Protist stage that produces gametes

Syngamy

Fusion of gametes during sexual reproduction

Conjugation

Exchange of genetic material between cells

Plasmodium (Slime Mold Stage)

Multinucleated mass that creeps across decaying matter

Pseudoplasmodium

Aggregation of cells representing primitive multicellularity

Radiolaria

Protists that use specialized structures for movement and food capture

Foraminifera

Marine protists possessing calcium-containing structures

Ciliophora (Ciliates)

Protists that move using cilia and are mostly free-living

Dinoflagellates

Protists associated with red tides, bioluminescence, and coral symbiosis

Red Tides

Harmful algal blooms commonly caused by dinoflagellates

Bioluminescence

Production of visible light by certain dinoflagellates

Diatoms

Photosynthetic protists that serve as major aquatic primary producers

Rainforests of the Oceans

Nickname for diatoms due to their major contribution to aquatic photosynthesis

Coccolithophores

Photosynthetic protists that produce calcium carbonate plates and may contribute to algal blooms

Algae

Photoautotrophic organisms possessing cell walls and inhabiting aquatic, terrestrial, or symbiotic environments

Forms of Algae

Can be unicellular, colonial, filamentous, membranous, sheet-like, or tubular

Eukaryotic Cell Walls

Never contain peptidoglycan

Plants and Algae Cell Walls

Composed primarily of cellulose and pectin

Fungal Cell Walls

Composed primarily of chitin and glucans

Endocytosis

Occurs only in eukaryotic cells