Lecture 5: Eukaryotic Cells

Flashcards covering eukaryotic cells, their structures, and the endosymbiotic theory.

Flagella and Cilia

External cellular structures used for motility, covered by an extension of the plasma membrane.

Flagella

Long, thin structures containing microtubules that slide back and forth, providing mechanical force to push the cell forward.

Cilia

More numerous structures composed of shorter microtubules that move in wavelike synchrony to propel the cell forward.

Glycocalyx / Extracellular Matrix (ECM)

Elaborate matrix that covers animal cells (which lack cell walls), providing protection, support, and adherence.

Cell Wall

Structure exterior to the cell membrane that provides support, maintains shape, and helps resist cell lysis, found in plant, fungal, and some protist cells.

Cellulose

The plant cell wall is made out of __ fibers, which are long chains of polysaccharides.

Chitin

The fungal cell wall is made out of __, a complex polysaccharide, and glycans.

Cell (Plasma) Membrane

Boundary that separates the living cell from its non-living environment, serving as a permeability barrier.

Facilitated Diffusion

Diffusion of substances aided by membrane transport proteins.

Active Transport

Movement of substances against the concentration gradient (low to high).

Phospholipid Bilayer

Two-layer sheet formed by phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward.

Fluid Mosaic

Description of membranes as fluid because molecules can move freely and mosaic because of the diversity of proteins.

Peripheral Proteins

Proteins bound to the surface of the membrane.

Integral Proteins

Proteins that penetrate the hydrophobic core; those spanning the membrane are called transmembrane proteins.

Transport Proteins

Allow transport of molecules across the membrane.

Enzymes (Membrane Proteins)

Catalyze chemical reactions.

Receptor Proteins

Detect presence of chemical messengers and initiate a chemical reaction within a cell.

Cell-Cell Recognition Proteins

Serve as identity markers that identify cells to other cells.

Adhesion Proteins

Join cells together into tissues.

Attachment Proteins

Attachment to the cytoskeleton and extracellular matrix (ECM).

Carbohydrates (Membrane)

Lipids covalently bonded to lipids or, more commonly, to proteins, acting as recognition markers.

Cholesterol

Molecules embedded in the hydrophobic areas of the inner region of the cell membrane to keep the membrane fluid.

Cytoplasm

Region of the cell outside the nucleus and within the plasma membrane, consisting of organelles suspended in cytosol.

Cytosol

The semifluid matrix that fills the interior of the cell.

Nucleus

Largest organelle containing most of the cell's genetic material in the form of DNA.

Chromosomes

Discrete units of DNA organized within the nucleus.

Nuclear Envelope

Double phospholipid bilayer surrounding the nucleus, containing pores for molecule entry and exit.

Nucleolus

Region within the nucleus where ribosomal RNA synthesis takes place.

Ribosomes

Small molecules made up of ribosomal RNA and proteins, functioning in protein synthesis.

Endoplasmic Reticulum (ER)

Network of internal membranes forming compartments, continuous with the nuclear envelope, with smooth and rough regions.

Smooth ER

ER region involved in lipid synthesis, carbohydrate metabolism, detoxification, and calcium storage.

Rough ER

ER region studded with ribosomes, involved in protein synthesis for proteins not destined for the cytosol.

Golgi Complex

Stacks of flattened membranous sacs (cisternae) that receive, refine, store, and distribute chemical products of the cell.

Lysosome

Membrane-enclosed sac of digestive enzymes that break down large molecules and perform digestive functions.

Peroxisomes

Organelles that contain oxidative enzymes to neutralize free radicals and detoxify alcohol and other drugs.

Vacuoles

Large vesicles derived from the endoplasmic reticulum and Golgi apparatus with various functions, including food storage and water regulation.

Cytoskeleton

Network of protein fibers extending throughout the cytoplasm, functioning in support and movement.

Microtubules

Hollow tubes of protein forming part of the cytoskeleton.

Microfilaments and Intermediate Filaments

Thinner, solid fibers forming part of the cytoskeleton.

Mitochondria

Organelles where cellular respiration takes place, generating most of the cell's energy in the form of ATP.

Chloroplasts

Plants and algae: sites of photosynthesis.

Stroma

The innermost compartment that holds a thick fluid which contains DNA, ribosomes, and enzymes.

Thylakoids

Membranous sacs suspended in the stroma.

Origin of Eukaryotic Cells Hypothesis

Theory that suggests eukaryotic cells evolved through a series of structural changes to an ancestral cell of the domain Archaea.

Endosymbiont

The theory suggests that one organism, an evolving, primitive eukaryotic cell, engulfed an ATP-generating bacterial cell (the endosymbiont).