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 (H 2 O 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

Vacuoles Usually fluid filled structures Storage 1. Animals – cytoplasm, temporary storage site, small 2. Plants – very large, hold water 3. 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.Chloroplast 2.Leucoplast – storage or proteins, lipids, starches 3.Chromoplast – yellow, red, and orange pigments

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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 O 2, CO 2, and H 2 O

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

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

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