Cell Structure and Function in Multicellular Organisms

Multicellular organisms

Organisms made up of many cells

Fibronectin

Connects cells to the ECM and helps organize components in the ECM

Laminin

Connects cells to the ECM and helps organize components in the ECM

Collagen

Forms large fibers and interconnected fibrous networks in the ECM; provides tensile strength

Elastin

Forms elastic fibers in the ECM that can stretch and recoil

Primary cell wall

Flexible cell wall that allows for size increase in plant cells

Secondary cell wall

Cell wall formed after plant cell maturation with layers of cellulose and lignins

Anchoring junctions

Hold adjacent cells together or attach cells to the ECM

Tight junctions

Prevent leakage of material between adjacent cells

Gap junctions

Permit the direct exchange of ions and small molecules between adjacent cells

Middle lamella

Polysaccharide layer that cements cell walls of adjacent plant cells

Plasmodesmata

Passageways between plant cells that permit direct diffusion of ions and molecules

Epithelial tissue

Continuous sheets of cells covering or lining body surfaces

Connective tissue

Supports body or connects tissues, rich in ECM

Nervous tissue

Receives, generates, and conducts electrical signals

Muscle tissue

Generates force to facilitate movement

Dermal tissue

Outer covering of plants

Ground tissue

Where chemical reactions like photosynthesis occur

Vascular tissue

Transports water and nutrients in plants

Plasma membrane

Encloses the cytoplasm and surrounds organelles

Phospholipid bilayer

Forms the core of the plasma membrane with hydrophobic and hydrophilic regions

Selective permeability

Allows passage of some ions and molecules while blocking others

Simple diffusion

Movement of a substance directly through the phospholipid bilayer without energy input

Facilitated diffusion

Diffusion of a solute with the help of a transport protein

Active transport

Movement of a substance against its concentration gradient, requiring energy

Isotonic

Solution with equal solute concentrations on both sides of a membrane

Hypertonic

Solution with higher solute concentration on one side of a membrane

Hypotonic

Solution with lower solute concentration on one side of a membrane

Crenation

Shrinkage of a cell in a hypertonic solution

Osmotic lysis

Swelling and bursting of a cell in a hypotonic solution

Plasmolysis

Plasma membrane pulls away from the cell wall due to water loss

Channels

Transmembrane proteins forming open passageways for diffusion

Transporters

Transmembrane proteins that change shape to move solutes across membranes

Uniporter

Transports a single molecule or ion

Symporter

Transports two or more ions or molecules in the same direction

Antiporter

Transports two or more ions or molecules in opposite directions

Primary active transport

Uses a pump to move substances with direct energy input

Secondary active transport

Uses a pre-existing gradient to drive transport

Electrogenic pump

Pump that exports one net positive charge from the cell

Exocytosis

Transport of materials out of the cell via vesicles

Endocytosis

Uptake of materials into the cell via vesicles

Pinocytosis

Internalization of extracellular fluid by the cell

Phagocytosis

Engulfing large particles like bacteria with a vesicle

Metabolism

Total of all chemical reactions occurring within an organism

Kinetic energy

Energy associated with movement

Potential energy

Energy due to structure or location

First law of thermodynamics

Energy cannot be created or destroyed, only transformed

Second law of thermodynamics

Energy transfer increases the entropy (disorder) of a system

Exergonic reaction

Spontaneous reaction with negative free energy change (ΔG < 0)

Endergonic reaction

Non-spontaneous reaction requiring energy input (ΔG > 0)

Catalyst

Substance that speeds up a chemical reaction without being consumed

Enzyme

Protein catalyst that speeds up chemical reactions in living cells

Active site

Location on an enzyme where the reaction takes place

Substrate

Reactant that binds to the active site of an enzyme

Enzyme-substrate complex

Complex formed when enzyme and substrate bind

Competitive inhibition

Inhibitor binds to the enzyme's active site

Noncompetitive inhibition

Inhibitor binds to a site other than the active site, reducing enzyme activity

Cofactor

Inorganic ion that temporarily binds to an enzyme

Coenzyme

Organic molecule that participates in enzyme reactions

Catabolic pathways

Breakdown of cellular components, releasing energy

Anabolic pathways

Synthesis of cellular components, requiring energy

Oxidation

Loss of electrons in a redox reaction

Reduction

Gain of electrons in a redox reaction

NAD+

Nicotinamide adenine dinucleotide, important in redox reactions

ATP

Primary energy carrier in cells

ADP

Lower energy form of ATP after a phosphate group is removed

Glycolysis

Breakdown of glucose to produce energy

Osmosis

Movement of water across a membrane to balance solute concentrations

Fluid mosaic model

Model of membrane structure where lipids and proteins can move freely

Membrane fluidity

Refers to the ability of lipids and proteins to move within the membrane

Cholesterol

Stabilizes the membrane structure, affecting fluidity depending on temperature