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