cellular organelles cellular transport. history 1665 – robert hooke – observation of cork cells...

•Cellular Organelles

•Cellular Transport

History•1665 – Robert Hooke – observation of cork cells

•1833 – Robert Brown – nucleus discovery

Robert Hooke’s work•

Cell Theory•Schleidan, Schwann, Virchow

–All organisms made up of one or more cells

–Cells are the basic unit of anatomy and physiology

–New cells come from existing cells by reproduction

2 basic types of cells• prokaryotic

• eukaryotic

Prokaryotic Cells• prokaryotic

– Pro = before/ kary = nucleus– Oldest known form of life– Very primitive– Small (about 1 micrometer)– No membrane bound organelles – Ex. bacteria

Eukaryotic Cells•Eu = true•Have membrane bound

organelles and a nucleus•Large (20 – 50) micrometers•Specialized organelles carry

out cell functions

Two main types of eukaryotic cells

•Plant Cells

•Animal Cells

Plant cell

Animal Cell•

Anatomy and Physiology•Cellular organelles found within eukaryotic cells

The Nucleus•Contains DNA•Surrounded

by nuclear membrane

•Brain of the cell

Interior of Nucleus•Inside are long thin strands of chromatin and nucleic acid

Anatomy of nucleus•Nucleolus –

makes and stores RNA and ribosomes

•Nuclear membrane – selectively permeable

Electron Micrograph of Nucleus•

Ribosomes•Site of protein synthesis– free floating or attached to rough ER

Mitochondria•“Power house” of the cell

•Enzymes release energy

Two membranes• Inner membrane –

“cristae” – folded like shelves to increase surface area

• Outer – separates organelle from cytoplasm

Electron Micrograph of Mitochondria•

Endoplasmic Reticulum•Transport of protein and lipids

Two types•Rough ER•Smooth ER

Rough Endoplasmic Reticulum•Site of protein synthesis•Transport to smooth ER

Smooth ER•No ribosomes•Forms vesicle

and transports to Golgi apparatus

Golgi Apparatus•Discovered by Camillio Golgi

Function• Proteins vesicles

enter • Carbohydrates

are added or material is concentrated (H2O removal)

• New membrane formed and secreted

Lysosomes•Recycling centers•Breaks down worn and

damaged cell structures•Unaffected by digestive

enzyme inside

Lysosomes•Common in animals

VacuolesUsually fluid filled structuresStorage

1. Animals – cytoplasm, temporary storage site, small2. Plants – very large, hold water3. Unicellular – digestion, storage, contractile vacuoles remove water and waste

Cytoskeleton• Miniature

internal support system in cytoplasm

• Composed of microtubules

• Give cells shape

Centrioles•Mostly in animals•Near nucleus•Composed of microtubules

•Cellular reproduction

Plastids•Plant cells only•Three types

–Chloroplast–Leucoplast–Chromoplast

Chloroplast•Most common•Green

pigment – chlorophyll

•Glucose is made

1.Chloroplast2.Leucoplast – storage or

proteins, lipids, starches3.Chromoplast – yellow,

red, and orange pigments

• http://biology.about.com/library/weekly/aa033000a.htm

• www.virtualcell.com

Plasma Membrane•Protective Barrier

•Selectively Permeable

Structure of membrane•Double layer of phospholipid molecules and proteins

•Constant motion

Function•Prevents large particles from entering

•Permits molecules like O2, CO2, and H2O

Cell Wall•Composed of cellulose•Gives shape and rigidity

3 parts•Primary cell wall – soft and

flexible•Secondary cell wall – develops

when cell reaches full size, gives strength

•Middle Lamella – jellylike polysachharide material called pectin

Part II

Cellular Transport

Cellular Transport•Regulated by the cell membrane

•Dependent on the type of solution and concentration gradient

3 Types of Solutions• Hypotonic – lower concentration

of solutes than solvent • Hypertonic – higher

concentration of solutes than solvent

• Isotonic – solution same on both sides of membrane

Examples•Hypotonic – distilled water + red blood cells

•Hypertonic – salt water + red blood cells

•Isotonic – animal red blood cells in 80% water

If the cell is in….•Distilled water….the cell will burst

•Salt water…the cell will shrink

2 Types of Cellular Transport•Passive Transport – NO energy required to get materials across concentration gradient

•Active Transport – energy required

3 types of Passive transport•Movement from high concentration to low concentration–Diffusion–Facilitated diffusion–Osmosis

Diffusion•Movement of molecules in gases and liquids from high concentration to low

•Ex. Food coloring in water, perfume in air

Facilitated diffusion•Carrier molecules carry other

molecules across concentration gradient–Very few molecules can do this–Proteins carry glucose molecules into red blood cells

Osmosis•Movement of molecules in liquids by going across a membrane

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Homeostasis•For a cell to survive, it must be able to maintain the process of homeostasis, maintenance of constant internal environment, despite external change

Active Transport•Energy is required to move

materials against the concentration gradient, from low concentration to high

•2 types–Endocytosis–Exocytosis

Endocytosis•Movement “inside” cell

–Pinocytosis – cell drinking–Phagocytosis – food particles•Ex. Amoeba engulfing food particles encased in vacuoles

Exocytosis•“outside” of cell

–Release of large molecules and waste products, membrane breaks open and vacuole is released

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