Cell Theory

Cell Theory

• Robert Hooke (1663)- Discovered cells– Used light microscope to look at cork– Noticed tiny compartments which he called

cells• Anton van Leeuwenhoek (1673)

– Observed living cells in pond water, animalcules, which were protists

Cell Theory• Matthais Schleiden (1838)• - concluded all plants are made up of cells• Theodor Schwann (1839) • -concluded that all animals are also made up

of cells.• Rudolf Virchow (1855)• - proposed that new cells are formed only

from existing cells

Cell Theory

• Hooke, Leeuwenhoek, Schleiden, Schwann, Virchow observations led to the cell theory

• All living things composed of cells• Cells are the basic unit of structure and

function for living things• All cells come from pre-existing cells

Cells

• Cells • Tissues • Organs• Organ system

2 Classes of cells

Prokaryote

• Unicellular• No nucleus or organelles

– DNA and RNA float in cell• 1-10 micrometers in size (smaller)• Ex: Bacteria

Eukaryote

• Unicellular and Multicellular• Nucleus with a membrane• Organelles with membranes• 10-100 micrometers (larger)• Ex: protists, fungi, plants, animals

Eukaryote

Prokaryote

Prokaryote (E. coli)

Prokaryote

Eukaryote (cheek cells)

Eukaryote

Prokaryote

Eukaryote

Eukaryote

Eukaryote

Prokaryote

Prokaryote

Cell Structure and Function

Nucleus-- contains DNA- directs activities of cell

Nuclear Envelope- membrane surrounding the nucleus- tiny pores

Nucleolus-- rich in RNA- makes organelles called ribosomes

Cell Structures and FunctionCytoplasm

- holds organelles Cytosol-gelatin-like aqueous fluid

Cell Membrane (Plasma Membrane)- keep functions of eukaryotic cells organized- regulate transport of substances in and out of cell- composed of proteins and lipids

Cell Structure and Function

Ribosome- made of proteins and RNA- Found on membranes or in cytoplasm- Produce proteins

Endoplasmic Reticulum(ER) – 2 membranes– Intercellular highway– Rough ER- ribosomes bound to outside

• Packages proteins in vesicles for export– Smooth ER- builds different enzymes to

enable organelles to perform functions

Cell Structure and Function

6. Golgi Apparatus- vesicles of ER travel here- modifies/stores/routes proteins and other chemical products to their next destination- 1 side receiving dock – refine and modify ER product- 1 side shipping side- sends vesicles to other locations

Cell Structure and Function7. Vacuoles- large membrane bound sacs

- Stores undigested nutrients - Helps get rid waste - In plant- larger in plants that animals

- contains colorful pigments- stores chemicals/ contributes to growth

8. Lysosomes- contain digestive enzymes to break down substances

- digest nutrients to nourish cell - help destroy harmful bacteria - engulfs and digests damaged organelles

Cell Structure and Function

9. Mitochondria- produces energy for cell through cellular respiration-ATP- main energy source- Consists of outer and inner membrane-Cristae- inner membrane, many folds- Folds increase surface area= increased respiration sites= increased ATP

Cell Structure and Function

Cytoskeleton- network of long protein strands in the cytosolMicrofilaments- actin molecules linked in a polymer chainMicrotubules- large strands with hollow tubes

Cell Structure and Function

Flagella- long, thin, whip like structures that project from cell

- allow movement with “S” shaped motion

Cilia- short and numerous- back and forth motion for movement

Plant CellCell Wall – Outside plasma membrane

- protects/maintains shape- Only in plants

Chloroplast- Photosynthetic organelles found in plant and algae cells– Outer membrane– Inner membrane(Stroma) - fluid filled space with

suspended disks– Disks (Thykaloids)- structures that trap light energy

and convert to chemical energy.

Membranes

Membranes

• Composed of lipids and proteins• phospholipid bilayer• 2 Tails- Hydrophobic • Head- Hydrophilic • Selectively Permeable-some substances can cross

and others cannot• Barrier for substances

Cell Membrane

• Peripheral proteins- proteins on the exterior or interior of the membrane

• Integral proteins- proteins embedded in the bilayer

• Function of Membrane Proteins– Help communicate with other cells– Transport substances across membrane– http://www.youtube.com/watch?v=ULR79TiUj80

&feature=related

Cell Membrane

• Fluid Mosaic Model- substances scattered through out membrane, can move around

Passive Transport• No energy is used• Diffusion-Net movement of particles in a

concentrated area to a less concentrated area to be equal– Molecules that can dissolve in lipids and are small

• Concentration Gradient-difference in concentrations of molecules across space

• Equilibrium- concentration of molecules is the same throughout space

Diffusion

Passive Transport• Osmosis- transport of water across

membrane from a high concentration to a lower concentration– Hypertonic- higher concentration of solute

outside the cell– Hypotonic-lower concentration of solute

outside cell– Isotonic-concentration of solute equal

Passive Transport

• Plasmolysis- hypertonic solution– Cells may shrivel and die– Occurs in plant cells, wilt if they don’t receive

water.– cytoplasm shrinks away from cells wall– Turgor pressure is lost

• Pressure that water molecules exert against the cell wall

Passive Transport

• Cytolysis- hypotonic environment• Water diffuses into the cells causing them

to swell and burst

Passive TransportFacilitated diffusion- Transport proteins

provide pathway for certain molecules to pass

Carrier proteins- transport the molecules• http://www.coolschool.ca/lor/BI12/unit4/U0

4L03/diffusion.swf• Ion Channels- channels that allow ions ti

passEx. sodium, potassium, calcium, chloride ions

Active Transport

• Uses energy to move molecules across membrane

• Specific transport protein pumps solute across a membrane in opposite direction it travels in diffusion

• Energy supplied by mitochondria• Carrier proteins that act as pumps

Active Transport

• Sodium Potassium Pump– Na+ binds to carrier protein inside cell– Carrier protien splits Phosphate group from

molecule of ATP and phosphate group binds• ATP supplies energy needed to reshape protein

– With new shape moves Na+ outside cell, and the shape is perfect to bind for K+

– Repeats

Vesicles • Vesicles- small membrane sacs for moving product

in, out, and within cell. • Exocytosis- vesicles exports product from cells

– Fuses out• Endocytosis- vesicle take material into cell

– Buds inward– Pinocytosis- transports of solutes or fluids– Phagocytosis-movement of large particles of whole cells– http://www.youtube.com/watch?v=4gLtk8Yc1Zc&featur

e=related

Cell Structure and Function

Cytoskeleton- Network of fibers within cytoplasm (2 fibers)– Microtubules- straight hollow tubes of protein

– Give Rigidity, shape, and organization to cell

– Microfilaments- thinner solid rods of proteins– Enable the cell to move and change shape