Ch 3

Plasma Membrane Functions

Physical isolation, regulation of exchange, sensitivity to environment, structural support.

Plasma Membrane Composition

Made of a phospholipid bilayer with embedded proteins and carbohydrates.

Phospholipid Structure

Hydrophilic heads face watery environments; hydrophobic tails form a barrier to water-soluble substances.

Cholesterol Function

Reduces fluidity and permeability of the plasma membrane.

Types of Membrane Proteins

Anchoring, recognition, enzymes, receptors, carriers, channels.

Glycocalyx

A sugar coating outside the membrane; aids in protection, binding, movement, and immune recognition.

Types of Organelles

Membranous and nonmembranous.

Cytoskeleton Components

Microfilaments, intermediate filaments, microtubules.

Microfilament Function

Provides support and aids in muscle contraction.

Intermediate Filament Function

Maintains shape and stabilizes organelles.

Microtubule Function

Provides strength, moves organelles, forms the spindle apparatus.

Microvilli

Projections that increase surface area for absorption.

Centrioles Function

Help form the spindle apparatus during cell division.

Cilia Function

Moves fluids across the cell surface.

Ribosome Function

Synthesizes proteins.

Smooth ER Role

Synthesizes lipids and stores glycogen.

Rough ER Role

Synthesizes and processes proteins.

Golgi Apparatus Function

Modifies, packages, and ships proteins and lipids.

Lysosomes Function

Break down waste, damaged organelles, and pathogens.

Peroxisomes Function

Break down fatty acids and neutralize hydrogen peroxide.

Mitochondria Role

Produce ATP through aerobic respiration.

Membrane Flow

Continuous movement and recycling of membrane parts.

Nucleus Functions

Controls metabolism, stores/processes genetic info, regulates protein synthesis.

Nucleoli

Nuclear structures that make rRNA and ribosomal subunits.

Chromatin vs. Chromosomes

Chromatin is loose DNA; chromosomes are tightly coiled for cell division.

Diffusion

Movement from high to low concentration.

Osmosis

Diffusion of water toward higher solute concentration.

Tonicity

Effect of solute concentration on cell shape (isotonic, hypotonic, hypertonic).

Carrier-Mediated Transport

Transport through membrane proteins—specific, saturable, and regulated.

Facilitated Diffusion

Passive transport using carrier proteins.

Primary Active Transport

Uses ATP to move substances against concentration gradients (e.g., Na⁺/K⁺ pump).

Secondary Active Transport

Uses gradient created by primary transport to move other substances.

Vesicular Transport

Uses vesicles and ATP to move materials in/out of the cell.

Types of Endocytosis

Receptor-mediated, pinocytosis, phagocytosis.

Exocytosis

Vesicles release materials outside the cell.

Transcytosis

Substance is transported across the entire cell.

Resting Membrane Potential

The electrical charge difference across the membrane (−10 mV to −100 mV).

Stages of the Cell Cycle

Interphase (G1, S, G2), M phase (mitosis + cytokinesis).

Mitosis

Division of the nucleus into two identical nuclei.

Cytokinesis

Division of the cytoplasm into two daughter cells.

Apoptosis

Genetically programmed cell death.

Stem Cells

Unspecialized cells that divide to produce new specialized cells.

Cellular Differentiation

Process where cells become specialized by turning off specific genes.

Cytoplasm

All materials between plasma and nuclear membranes, including cytosol and organelles.

Cytosol

Intracellular fluid containing dissolved nutrients, ions, proteins, and waste products.

Proteasomes Function

Contain enzymes that break down and recycle damaged or unneeded proteins.

Inclusions

Masses of insoluble materials in cells, such as stored nutrients or pigment granules.

Centrosome

Region near the nucleus that organizes microtubules and contains centrioles.

Motile Cilia Purpose

Move substances like mucus across cell surfaces in respiratory and reproductive tracts.

Nuclear Envelope

Double membrane surrounding the nucleus, connected to the ER and contains nuclear pores.

Aquaporins

Water channel proteins in the plasma membrane that facilitate rapid osmosis.

Sodium–Potassium Pump

A membrane protein that uses ATP to pump 3 Na⁺ out and 2 K⁺ into the cell.

Membrane Potential Function

Helps conduct electrical impulses and powers transport processes across the membrane.

Nucleus Purpose

Controls the cell and stores DNA.

Ribosomes Purpose

Make proteins.

Rough ER Function

Helps make and package proteins (has ribosomes on it).

Smooth ER Function

Makes lipids and helps detoxify drugs.

Golgi Apparatus Function

Modifies, sorts, and ships proteins.

Lysosomes Function

Break down waste, old parts, and bacteria.

Peroxisomes Function

Break down fatty acids and toxins.

Mitochondria Function

Produce energy (ATP) from food.

Cytoskeleton Role

Gives the cell shape and helps it move things inside.

Centrioles Role

Help organize the spindle for cell division.