Cell Structure and Function in Multicellular Organisms

Multicellular Organisms

Cells form tissues, organs, and systems hierarchically.

Structural Hierarchy

Levels include cells, tissues, organs, systems, organisms.

Cell Functions

Cell activities represent biological work requiring energy.

Prokaryotes

Simple, unicellular organisms without a nucleus.

Prokaryotic Features

Lack nucleus, have cell walls, circular DNA.

Chromosome Structure

Condensed during division, relaxed when resting.

Fluid-Mosaic Model

Describes cell membrane's dynamic structure and function.

Active Transport

Requires energy to move substances against gradient.

Diffusion

Passive movement of molecules from high to low concentration.

Facilitated Diffusion

Passive transport via protein channels or carriers.

Osmosis

Diffusion of water across a selectively permeable membrane.

Hypotonic Solution

Lower solute concentration outside cell, causes swelling.

Osmotic Pressure

Pressure required to prevent water movement across membrane.

ATP

Adenosine triphosphate, energy currency of cells.

Eukaryotes

Complex cells with membrane-bound organelles.

Domains of Life

Bacteria and Archaea contain prokaryotic organisms.

Domain Eukarya

Includes kingdoms: Animalia, Plantae, Fungi, Protista.

Animal Cells

Lack cell walls, have centrioles and lysosomes.

Plant Cells

Contain cell walls, chloroplasts, and large vacuoles.

Nuclear Membrane

Regulates transport via nuclear pores.

Endomembrane System

Includes ER, Golgi, vesicles; functions in transport.

Mitochondria

Powerhouse of the cell, produces ATP.

Chloroplasts

Site of photosynthesis, converts sunlight to energy.

Cilia vs Flagella

Cilia are short, numerous; flagella are long, few.

Cytoskeleton

Provides structural support, aids in movement.

Selectively Permeable Membrane

Allows certain molecules to pass, blocking others.

Passive Transport

Movement without energy, down concentration gradient.

Isotonic Solution

Equal solute concentration inside and outside cell.

Hypertonic Solution

Higher solute concentration outside cell, causes shrinkage.

Hydrostatic Pressure

Pressure exerted by a fluid at equilibrium.

Protein Transport

Proteins assist in both passive and active transport.

Vesicle Transport

Active transport involving membrane-bound vesicles.

Exocytosis

Process of expelling materials from the cell.

Endocytosis

Process of taking materials into the cell.

Pinocytosis

Cell drinking; uptake of liquid substances.

Phagocytosis

Cell eating; uptake of large particles.

Enzymes

Biological catalysts that speed up chemical reactions.

Substrate

Reactant molecule upon which an enzyme acts.

Activation Energy

Energy required to initiate a chemical reaction.

Competitive Inhibitors

Compete with substrate for enzyme's active site.

Noncompetitive Inhibitors

Bind to enzyme, altering its function without competing.

Induced Fit

Enzyme changes shape to better fit substrate.

Cell Theory

All living organisms are composed of cells.