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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. EukaryoteAll 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
OrganellesOrganelles
• 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 Is a small
dense region dense region in the nucleusin the nucleus
• Makes Makes ribosomesribosomes, , which make which make proteinsproteins
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
• http://www.youtube.com/watch?v=kxSLw1LMvgk
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 http://www.youtube.com/watch?v=-V7LTyJuAy4&feature=related
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