Lecture Notes: Eukaryotic Cells and Organelles

Vocabulary flashcards covering key terms from the lecture notes on eukaryotic cells and organelles.

Eukaryotic cell

A cell with a nucleus and membrane-bound organelles; typically larger than prokaryotic cells.

Prokaryotic cell

A cell lacking a true nucleus and membrane-bound organelles; DNA is usually in a nucleoid region.

Nucleus

Information-central organelle containing the cell's DNA; enclosed by a nuclear envelope.

Nuclear envelope

Double phospholipid bilayer surrounding the nucleus with nuclear pores for transport.

Nuclear pores

Openings in the nuclear envelope that permit RNA export and protein import.

Chromatin

DNA wrapped around proteins; condenses into chromosomes during cell division.

Chromosome

Condensed DNA-protein structure visible during cell division.

Nucleolus

Site of ribosomal RNA (rRNA) synthesis within the nucleus.

Ribosomal RNA (rRNA)

RNA component of ribosomes; produced in the nucleolus.

Plasma membrane

Selective barrier regulating entry and exit of oxygen, nutrients, and waste.

Phospholipid bilayer

Two-layer structure of phospholipids forming the cell membrane.

Hydrophilic head

Polar head region of a phospholipid that faces aqueous environments.

Hydrophobic tail

Nonpolar tail region of a phospholipid that faces inward away from water.

Endomembrane system

Network regulating protein traffic and metabolism; includes ER, Golgi, lysosomes, vacuoles, and plasma membrane.

Rough Endoplasmic Reticulum (RER)

ER with ribosomes; site of synthesis for secreted or membrane-inserted proteins.

Smooth Endoplasmic Reticulum (SER)

ER without ribosomes; lipid synthesis, Ca2+ storage, detoxification, and carbohydrate metabolism.

Golgi apparatus

Modifies, sorts, and packages proteins and lipids for delivery in vesicles.

Glycosylation

Addition of carbohydrate groups to proteins or lipids in the Golgi.

Lysosome

Membrane-bound vesicle with hydrolytic enzymes that digest macromolecules and pathogens.

Vacuole

Storage and transport vesicles; various types include central, food, and contractile.

Central vacuole

Large plant cell vacuole that maintains turgor and stores water, ions, and pigments.

Food vacuole

Vacuole in animal cells that stores ingested material.

Contractile vacuole

Vacuole in freshwater protists that expels excess water.

Mitochondrion

Site of cellular respiration; produces ATP; double membrane with cristae.

Cristae

Folds of the inner mitochondrial membrane increasing surface area.

Mitochondrial matrix

Internal fluid containing enzymes for metabolic reactions inside mitochondria.

Mitochondrial DNA

Circular DNA present in mitochondria.

Chloroplast

Plant cell organelle conducting photosynthesis; contains chlorophyll.

Thylakoid membrane

Stacked membranes (grana) where light reactions occur.

Grana

Stacks of thylakoids within chloroplasts.

Stroma

Fluid surrounding the thylakoids; contains enzymes for carbon fixation.

Calvin cycle

Carbon-fixation reactions in chloroplasts producing sugars using ATP and NADPH.

Chlorophyll

Green pigment that captures light energy for photosynthesis.

ATP

Adenosine triphosphate; primary energy currency of the cell.

NADPH

Electron donor produced in light reactions used in the Calvin cycle.

Peroxisome

Single-membrane vesicle that breaks down hydrogen peroxide and performs beta-oxidation.

Beta-oxidation

Breakdown of very-long-chain fatty acids; occurs in peroxisomes.

Cytoskeleton

Network of fibers providing shape, support, and movement.

Microtubules

Thick, tubelike filaments for cell shape, transport, and mitotic spindle.

Microfilaments (actin)

Thin filaments involved in cell movement, contraction, and cytokinesis.

Intermediate filaments

Filaments providing mechanical stability and maintaining cell shape.

Centrosome

Microtubule-organizing center near the nucleus.

Centrioles

Paired structures in the centrosome with nine triplets of microtubules; organize spindle fibers.

Microtubule organizing center

Site where microtubules originate and are nucleated during division.

Flagella

Long, whip-like projections used for locomotion; usually few in number.

Cilia

Short, numerous projections that beat rhythmically to move cells or fluids.

Flagellum

Single flagellum; typically exhibits a 9+2 arrangement of microtubules.

Cilium

Single cilium; commonly displays a 9+2 microtubule arrangement.

Plant cell wall

Extracellular cellulose-based layer surrounding plant cells; provides structure.

Primary cell wall

Thin, flexible layer allowing growth.

Middle lamella

Pectin-rich layer that glues adjacent plant cells together.

Secondary cell wall

Thick, lignified layer providing additional rigidity (optional).

Extracellular Matrix (ECM)

Complex network of glycoproteins surrounding animal cells that provides support and signals.

Collagen

Fibrous protein in ECM providing tensile strength.

Proteoglycans

Protein–carbohydrate complexes that retain water and cushion cells.

Fibronectin

Glycoprotein that mediates cell–matrix adhesion.

Integrin

Transmembrane receptors that bind ECM and mediate signaling.

Integrin signaling

ECM signals influencing cell behavior via integrins.