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

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

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

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  

Specialization Unicellular organisms  living organisms that are only ONE cell –Examples: bacteria, algae, protists, yeast Multicellular organisms  any organism that is made of more than one cell –Evolved later

Prokaryote vs. Eukaryote All cells have a membrane, cytoplasm, DNA & ribosomes Prokaryotic Cells –DNA not bound by a membrane… no “true nucleus” –Usually smaller, simple –No membrane bound parts (organelles) –Ex: bacteria Eukaryotic Cells –Membrane bound nucleus –Larger, complex, internal organization –Have internal membrane bound structures –Ex: you, plants, algae

Can unicellular organisms be eukaryotic? What does that mean? Do prokaryotes have DNA? What is an example of a prokaryote? Are prokaryotes considered to be alive?

Basic Cell Structures Cell membrane Nucleus -nucleolus -nuclear envelope Cytoplasm

Organelles Very small size Can only be observed under a microscope Have specific functions Found throughout cytoplasm Include: Cytoplasm, Nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, mitochondria, chloroplasts (plants only), cytoskeleton, centrioles (Animal only)

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

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

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

ENDOPLASMIC RETICULUM Internal membrane Lipid parts of the cell membrane made here Makes proteins etc. for shipment out of cell Can be “Rough” or Smooth

GOLGI APPARATUS Modifies, sorts, packages proteins and other products Destination – storage in cell – export out of cell Customizes Adds lipids, carbs to protein

LYSOSOMES Small, enzyme-filled organelles Digests material for use or disposal –Only common in animals Tay Sachs disease has dysfunctional lysosomes in neural cells which allows fats to accumulate

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

CHLOROPLASTS Capture sunlight & convert it to energy –Photosynthesis Have 2 membranes Contain the green pigment chlorophyll Has its own DNA!

VACUOLES Stores materials Water, salts, protein, carbs Largest in plants –Gives turgor pressure May not be present in animals

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

CENTRIOLES Help in the process of cell division Only in Animals

PLANTS V. ANIMALS CELL WALLS LARGE VACUOLE CHLOROPLASTS CENTRIOLES NO central VACUOLE NO CHLOROPLASTS

Awesome cell clip LMvgkhttp:// LMvgk

Cooperation Among Cells UNICELLULAR: Each individual cell is its own organism, but may form: - Colonies – Volvox, colonial algae - Biofilms – Bacteria on teeth, plaque What are the advantages of cooperating? Disadvantages? MULTICELLULAR Cells are specialized (specific roles) - eventually form tissues  organs  systems What are our specialized cell types?

Volvox

Colonies of Bacteria

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

Can you find the connection?

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