Cell Structure and Function: Prokaryotes vs Eukaryotes

Cell Theory

Principle stating cells are life's basic units.

Plasma Membrane

Separates cell's interior from external environment.

Cytoplasm

Gel-like substance where cell components reside.

DNA

Genetic material that carries hereditary information.

Ribosomes

Cell structures that synthesize proteins.

Prokaryotes

Organisms without membrane-bound organelles.

Eukaryotes

Organisms with membrane-bound organelles.

Peptidoglycan

Component of prokaryotic cell walls.

Nucleoid

Region in prokaryotes containing chromosomal DNA.

Surface Area-to-Volume Ratio

Determines cell size efficiency for material exchange.

Nuclear Envelope

Double membrane separating nucleus from cytoplasm.

Nuclear Pores

Regulate molecule flow between nucleus and cytoplasm.

Chromatin

Unwound DNA in the nucleus during growth.

Chromosomes

Structures made of DNA, visible during cell division.

Nucleolus

Site of ribosome assembly within the nucleus.

Mitochondrion

Powerhouse of the cell, converts energy to ATP.

Cristae

Folds in the inner mitochondrial membrane.

Mitochondrial Matrix

Space enclosed by the inner mitochondrial membrane.

Cytoskeleton

Network providing structural support in eukaryotic cells.

Eukaryotic Ribosomes

Larger ribosomes made of rRNA and proteins.

Cell Wall

Rigid outer layer in prokaryotic cells.

Organelles

Specialized structures within eukaryotic cells.

Peroxisomes

Organelles that detoxify poisons and break down fatty acids.

Lysosomes

Contain digestive enzymes for biomolecule breakdown.

Vacuoles

Membrane-bound sacs for storage and transport.

Vesicles

Small membrane-bound sacs for transport within cells.

Centrosome

Microtubule organizing center with two centrioles.

Centrioles

Cylinders of microtubules at right angles.

Cell Wall

Rigid structure providing protection in plant cells.

Chloroplasts

Double-membrane organelles for photosynthesis in plants.

Thylakoids

Stacked membrane sacs within chloroplasts for light reactions.

Granum

Stack of thylakoids in chloroplasts.

Central Vacuole

Large vacuole regulating water and cell expansion.

Endomembrane System

Network of membranes for lipid and protein transport.

Endoplasmic Reticulum (ER)

Interconnected membranes modifying proteins and synthesizing lipids.

Rough ER

ER with ribosomes, modifies and synthesizes proteins.

Smooth ER

ER without ribosomes, synthesizes lipids and detoxifies.

Sarcoplasmic Reticulum

Specialized SER storing Ca2+ in muscle cells.

Golgi Apparatus

Processes, sorts, and packages proteins and lipids.

Cis Face

Receiving side of the Golgi apparatus.

Trans Face

Shipping side of the Golgi apparatus.

Microtubule Organizing Centers (MTOCs)

Structures organizing microtubules in eukaryotic cells.

Cellulose

Polysaccharide making up plant cell walls.

Chlorophyll

Green pigment capturing light energy for photosynthesis.

Golgi Apparatus

Modifies proteins and lipids for sorting.

Secretory Vesicles

Buds from trans face of Golgi.

Cytoskeleton

Network of protein fibers maintaining cell shape.

Microfilaments

Involved in cell movement and shape stabilization.

Intermediate Filaments

Structural support maintaining cell shape.

Microtubules

Provide framework for motor proteins in cells.

Cilia

Short, numerous structures for cell movement.

Flagella

Long, fewer structures for cell propulsion.

Extracellular Matrix

Supports and connects animal cells with proteins.

Plasmodesmata

Channels connecting plant cell cytoplasm.

Tight Junctions

Watertight seals preventing leakage between animal cells.

Desmosomes

Spot welds joining adjacent cells in tissues.

Gap Junctions

Channels allowing material movement between animal cells.

Plasma Membrane

Defines cell border and regulates entry/exit.

Fluid Mosaic Model

Membrane structure with diverse components and fluidity.

Phospholipids

Amphiphilic molecules forming the membrane bilayer.

Hydrophobic Tails

Nonpolar fatty acid chains in phospholipids.

Hydrophilic Head

Polar phosphate group in phospholipids.

Integral Proteins

Proteins embedded within the phospholipid bilayer.

Peripheral Proteins

Proteins located on membrane surfaces.

Connexons

Structures formed by connexins in gap junctions.

Actin Monomers

Building blocks of microfilaments.

Tubulin Dimers

Building blocks of microtubules.

Oligosaccharide Carbohydrates

Bound to proteins/lipids on membrane surface.

Glycoproteins

Proteins with carbohydrate chains for cell recognition.

Glycolipids

Lipids with carbohydrate chains for cell attachment.

CD4 Receptor Glycoproteins

Recognize HIV as 'self' in T cells.

Membrane Fluidity

Flexibility of membrane structure is essential.

Saturated Fatty Acids

Increase membrane rigidity by packing closely.

Unsaturated Fatty Acids

Decrease rigidity, allowing more membrane fluidity.

Cholesterol

Buffers membrane fluidity in varying temperatures.

Asymmetry of Plasma Membrane

Inner and outer surfaces have different compositions.

Selectively Permeable

Allows specific molecules to pass through membrane.

Passive Transport

Movement of molecules without energy input.

Active Transport

Movement of molecules requiring energy (ATP).

Semipermeable

Allows selective passage of materials across membrane.

Diffusion

Movement from high to low concentration.

Equilibrium

State where net movement of molecules ceases.

Factors Affecting Diffusion

Concentration, mass, temperature, and distance influence rates.

Facilitated Passive Transport

Transport through proteins down concentration gradients.

Channel Proteins

Integral proteins allowing specific ion/polar passage.

Gated Ion Channels

Open in response to specific signals.

Aquaporins

Channel proteins specific for water transport.

Carrier Proteins

Bind and transport specific substances across membrane.

Concentration Gradient

Difference in concentration affecting diffusion speed.

Surface Area

Larger area increases diffusion rates.

Solvent Density

Higher density reduces diffusion rates.

GLUTS

Glucose transport proteins facilitating glucose movement.

Osmosis

Diffusion of water across a selectively permeable membrane.

Tonicity

Effect of extracellular solution on cell volume.

Osmolarity

Total solute concentration in a solution.

Hypertonic

Extracellular fluid with higher osmolarity than cytosol.

Isotonic

Extracellular fluid with equal osmolarity to cytosol.

Hypotonic

Extracellular fluid with lower osmolarity than cytosol.

Turgor Pressure

Pressure from plasma membrane against cell wall.

Plasmolysis

Cell membrane detachment from cell wall in hypertonic solutions.