CELLS & the ORGANELLES Prokaryote vs. Eukaryote Animal vs. Plant Cells

“Life is Organized” Atoms C,H,N,O,P,S Molecules Organelles Cells Tissues Organs Organ Systems Organism Species Population Community Ecosystem Biome Ex: Tundra, desert, temperate forest Biosphere Smallest / most simple Largest / most complex

Early Microscopes Robert Hooke (1665)  Coined the term “cell” (Why?)  looking at cork, he saw little boxes  Is cork alive? Anton von Leeuwenhoek (1674)  saw living cells in pond water Cells

Cell Discoveries Matthias Schleiden (1838)  Plants are made of cells Theodor Schwann (1839)  Animals are made of cells Rudolf Virchow (1855)  Saw dividing cells  new living cells come from pre-existing cells Cells

The Cell Theory 1. All living things made of cells. 2. Cell are the basic unit of structure & function for life. 3. Cells can only arise from pre-existing living cells Cells

Types of Organisms Unicellular organisms  living organisms that are composed of only ONE cell –Examples: bacteria, algae, protists, yeast Multicellular organisms  any organism that is made of MORE THAN ONE cell –Evolved later Cells

Prokaryote vs. Eukaryote Prokaryotic Cells –DNA not bound by a membrane… no “true nucleus” –Usually smaller, simple Nearly all unicellular –No membrane bound parts (organelles) Ex: bacteria –Read Section 6.3 Eukaryotic Cells –DNA is bound by a membrane bound nucleus –Larger, complex, has internal organization –Have internal membrane bound structures = organelles Ex: you, plants, algae

Cells

Basic Structures For ALL Cells Cell membrane –Surround the cell – barrier between inside and environment Cytoplasm –Contains water and organelles DNA –Instructions for the cell to carry out Ribosomes –Makes proteins Cells

Organelles Very small size Have specific functions – Create specificity of cells EX: muscle cells have more mitochondria than skin cells Found throughout cytoplasm Examples: – Nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, chloroplasts (plants only), vacuoles, cytoskeleton, centrioles (Animal only) Cells

The Nucleus: Control center of the cell, houses genetic material Cells

Nucleolus Is a small dense region in the nucleusIs a small dense region in the nucleus Makes ribosomes, which make proteinsMakes ribosomes, which make proteins Cells

RIBOSOMES Free floating in cytoplasm or Attached to ER “reads” RNA code from DNA to assemble proteins “protein factory” Cells

ENDOPLASMIC RETICULUM Internal passageway within the cell Can be “Rough” or Smooth –Rough has ribosomes attached  protein synthesis –Smooth has no ribosomes  membrane lipid synthesis, detoxification, cholesterol metabolism Cells

GOLGI APPARATUS Modifies, sorts, packages proteins coming from ER Destination of products – storage in cell – export out of cell Customizes –Adds lipids, carbs to proteins Cells

LYSOSOMES Small, enzyme-filled organelles Digests material for use or disposal –Only common in animals but recent evidence suggest they are in plants as well Cells

MITOCHONDRIA Convert food into usable energy Have an outer & inner membrane Has its own DNA! –Inherited from your mom Cells

CHLOROPLASTS Capture sunlight & convert it to energy –Photosynthesis – make their own food –Green plants and some algae Have 2 membranes Contain the green pigment chlorophyll Has its own DNA! Cells

VACUOLES Stores materials Water, salts, protein, carbs Largest in plants –Gives turgor pressure Larger in plants Cells

CYTOSKELETON Structural support & transport MICROFILAMENTS Actin – threadlike protein MICROTUBULES Tubulins – protein basis of cilia & flagella Cells

CENTRIOLES Help in the process of cell division Only in Animals Cells

PLANTS V. ANIMALS CELL WALLS made of cellulose LARGER VACUOLE CHLOROPLASTS CENTRIOLES Smaller or No vacuoles Cells

Colonies Cells Chlamydomonas Volvox Volvox is a colony of individual cells. Each cell of a Volvox resembles a Chlamydomonas (a one-celled organism). Volvox cells coordinate the beating of their flagella so that the movement is not random through water. - shows cooperation among cells Colonies – a group of unicellular microorganisms living together If colony attaches to a solid surface = biofilm VS

Colonies of Bacteria Cells

Cell to Cell Connections Cells in same tissue communicate with each other through junctions –Tight junction : membranes are fused, stitched together; no passage –Desmosomes: protein fibers that anchor in cytoplasm of neighboring cells – allow passage of materials –Gap junction : Channels formed by donut-shaped proteins btwn cells ; yes passage –Pits & Plasmodesmata : (plants) cell walls perforated with pits, strands of cytoplasm (plasmodesmata) run through pits connecting cells Cells

Cell to Cell Connections Cells

Extracellular Matrix Solution of macromolecules (proteins & carbs) that surround cells in a tissue –Secreted by the cell itself to the space outside Holds cells together Allows them to migrate & interact May regulate behavior in cells –Ex: collagen Cells

Division of Labor In Multicellular Organisms Cells Tissues – a group of cells working together Organs – a group of tissues working together Organ System – a group of organs working together Organism – a group of organ systems working together Differentiation – when cells take on a specific role