Chapter 3The Cell

3.1Our understanding of the cell grew as

microscope quality improved.

Cell TheoryMainly Schleiden, Schwann, VirchowAll organisms are made of cellsAll existing cells are produced by other cellsThe cell is the most basic unit of life.

General Cell CharacteristicsTend to be microscopicEnclosed in a membraneFilled with cytoplasm

Types of cellsProkaryotic

No nucleusNo membrane bound organellesLike bacteria

Eukaryotic NucleusMembrane bound organellesLike not bacteria

3.2Cells have an internal structure

Cytoskeleton Support and shapePosition and transport organellesStrength Assists in cell divisionCell movement

NucleusStores genetic informationControl center of the cell

Endoplasmic ReticulumTransportRough: has ribosomes for processing

proteinsSmooth: no ribosomes, process lipids and

carbohydrates

RibosomesMade of rRNAForm proteins

Golgi apparatusGolgi bodiesPackaging and shipping

VesiclesMembrane bound sacksStorage

Mitochondria Energy

Vacuoles Like little warehousesStorage

LysosomesWaste disposalDigest material

CentriolesTubes in centrosomesHelp in mitosisForm cilia and flagella

Plant cell partsChloroplasts: where photosynthesis occursHave a cell wall of cellulose for support

3.3Cell membrane

Functions Enclose cell like a fence doesControls passage of stuff like a fence does

Structure Phospholipid bilayerProteins, carbohydrates, and lipids may be

imbedded in the membraneThe fluid mosaic model

Selectively permeableLets some stuff in, keeps other stuff out.

Kinda like a fence does

Receptors A substance can bind to its receptorCauses an action on the other side of the

membrane

3.4Stuff can move across cell membranes

Transport Passive: just happensActive: requires energy

Passive transportDiffusion: stuff diffuses from regions of high

concentration to regions of low concentrationOsmosis: diffusion of water

Three types of solutionsHypotonic:

Lower concentration Water moves out of cell

Hypertonic Higher concentration Water moves out of cell

Isotonic Same concentration No net movement of water

Examples

Facilitated diffusionSome molecules can only diffuse through

transport proteins.• Facilitated diffusion is diffusion

through transport proteins. • Revolving door

3.5Some transport requires energy

Active transportRequires energyGoes against a gradient

TypesPumpsEndocytosis: takes material into the cell

Pinocytosis: cell drinkingPhagocytosis: cell eating

Exocytosis: expels material from the cell