Chapter 3 Video Notes: Osmosis, Tonicity, Cell Structure, Endomembrane System, Metabolism, and Enzymes

Vocabulary flashcards covering the key terms from osmosis, tonicity, blood cell behavior, cell structure, endomembrane system, metabolism, enzymes, and the extracellular matrix.

Solute

A dissolved substance in a solution.

Solvent

Substances that dissolve other substances.

Solution

A mixture of a solute dissolved in a solvent.

Tonicity

The concentration of solute on opposite sides of a semi-permeable membrane.

Isotonic

Solute concentration is the same inside and outside the cell; water movement is balanced.

Hypertonic

Outside concentration is higher than inside; water moves out and the cell shrinks.

Hypotonic

Outside concentration is lower than inside; water moves in and the cell swells.

Osmosis

Diffusion of water across a selectively permeable membrane.

Isotonic saline (0.9% NaCl)

An isotonic solution where red blood cells maintain their normal shape.

Crenation

Shrinking of red blood cells in a hypertonic solution.

Hemolysis

Bursting of red blood cells in a hypotonic environment.

RBC (Red Blood Cell)

Blood cell responsible for carrying oxygen; commonly used in tonicity examples.

Plasma membrane

Outer surface of the cell that regulates entrance and exit of molecules.

Cytoskeleton

Protein fiber network that maintains cell shape and assists movement; includes microtubules, intermediate filaments, and actin filaments.

Microtubules

Thick protein filaments that provide tracks for organelles and form spindle apparatus during cell division; part of the flagella and cilia.

Intermediate filaments

Medium-sized filaments that provide structural support and strength.

Actin filaments

Thin protein filaments involved in cell movement and shape.

Centrioles

Short cylinders of microtubules that help organize spindle apparatus during cell division.

Centrosome

Microtubule organizing center that contains a pair of centrioles.

Lysosome

Vesicle containing digestive enzymes to break down molecules.

Vesicle

Membrane-bounded sac that stores and transports substances.

Cytoplasm

Semifluid matrix outside the nucleus that contains organelles.

Nucleus

Control center of the cell; contains DNA and regulates cellular activities.

Chromatin

Diffuse threads of DNA and protein that condense into chromosomes during division.

Nucleolus

Region inside the nucleus that produces RNA and ribosomes.

Nuclear envelope

Double membrane surrounding the nucleus.

Nuclear pores

Channels in the nuclear envelope that regulate traffic into and out of the nucleus.

Nucleoplasm

Fluid inside the nucleus.

Rough endoplasmic reticulum (RER)

ER studded with ribosomes; site of protein synthesis.

Smooth endoplasmic reticulum (SER)

ER lacking ribosomes; synthesizes lipids.

Ribosome

RNA-protein complex that carries out protein synthesis; may be free in cytoplasm or attached to RER.

Golgi apparatus

Stacks of flattened sacs that modify, package, and secrete proteins and lipids.

Mitochondrion

Site of cellular respiration and ATP production; double membrane with cristae.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for respiration.

ATP

Adenosine triphosphate; main energy currency of the cell.

Glycolysis

Glucose is broken into pyruvate in the cytoplasm; anaerobic; yields 2 ATP and NADH.

Citric acid cycle (Krebs cycle)

Cycle in the mitochondrial matrix that processes pyruvate to produce ATP and energy carriers.

Electron transport chain

Carrier proteins in the inner mitochondrial membrane that transfer electrons; oxygen is the final electron acceptor; produces most ATP.

NADH

Reduced form of NAD+, electron carrier produced in glycolysis and the Krebs cycle.

Fermentation

Anaerobic pathway; glycolysis proceeds when oxygen is unavailable; yields 2 ATP and lactate.

Lactate

Waste product produced during anaerobic fermentation.

Metabolism

All chemical reactions occurring in the body.

Metabolic pathway

A sequence where the product of one reaction becomes the reactant for the next.

Enzyme

Protein catalysts that speed up chemical reactions; reusable and highly specific.

Substrate

Molecule that an enzyme acts upon.

Active site

Region of the enzyme where the substrate binds.

Lock-and-key model

Concept that substrates fit precisely into the enzyme’s active site.

Activation energy

Energy required to start a chemical reaction; enzymes lower Ea.

Endomembrane system

Network of membranes (nuclear envelope, ER, Golgi, lysosomes, vesicles) that processes and transports cellular materials.

Extracellular matrix (ECM)

Non-cellular network surrounding cells that provides structural and biochemical support.

Collagen

ECM protein that resists stretching and provides tensile strength.

Elastin

ECM protein that allows tissues to stretch and recoil.

Fibronectin

ECM protein that binds to integrin and connects to the cytoskeleton.

Integrin

Transmembrane receptor linking ECM to the cytoskeleton.

Adhesion junction

Junction that attaches the cytoskeletons of adjacent cells.

Tight junction

Junction that forms a barrier to prevent leakage between cells.

Gap junction

Channel-forming junction that enables intercellular communication.

Prokaryotic vs Eukaryotic

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have a nucleus and organelles.

Selectively permeable

Membranes that allow some substances to cross while blocking others.