There is a common structure that makes up all living things…cells.

Cells are the Basic unit of life.

The cell theory grew out of the work of many scientists and improvements in the microscope.

•1665 First cells: Hooke

•1674 pond water (living cells): Leeuwenhoek (invented microscope)

•1838 All plants are made of cells: Schleiden

•1839 All animals are made of cells: Schwann

•1855 All cells come from other cells: Virchow

The findings of these scientists are summarized in the The findings of these scientists are summarized in the Cell Theory:Cell Theory:All living things are composed of cellsAll living things are composed of cellsCells are the basic units of structure and function for all Cells are the basic units of structure and function for all living thingsliving thingsNew cells are produced from existing cells.New cells are produced from existing cells.

Two Types of Cells: Prokaryotic and Eukaryotic Cells

• Prokaryotic (before nucleus)

– Small and most primitive– Unicellular– All have cell walls and cell

membranes– Contain DNA, ribosomes

and cytoplasm, but no nucleus or membrane bound organelles

– Ex. bacteria

Bacterium(colored SEM; magnification 8800x)

Two Types of Cells: Prokaryotic and Eukaryotic Cells

• Eukaryote (true nucleus)

– Have a true nucleus– Have membrane bound

organelles– All have cell membranes– May have cell walls– Can be unicellular or

multicellular– More evolved cells– Some have cilia– Ex. Plants, animals, fungi,

protists (no bacteria)

Eukaryotic Cells: Plant cells differ from animal cells.

• Animal cells– Can be all kinds of

shapes– Contain: DNA,

cytoplasm, ribosomes, cytoskeleton, cell membrane,mitochondria, golgi apparati, nucleus, nucleolus, and smooth & rough ER, centrioles, and lots of lysosomes

• Plant cells contain:– DNA, cytoplasm,

ribosomes, cytoskeleton, cell membrane,mitochondria, golgi apparati, nucleus, nucleolus, and smooth & rough ER

– contain cell walls– Chloroplasts– Central vacuoles– Usually boxy or square

shaped

Cell Components: Cell Membrane

• Function: Protects cells, controls what enters and leaves the body of the cell

• Composed of phospholipid bilayer, proteins and carbohydrates

Cell Components: cytoskeleton• Network of proteins

that form long threads or fibers that crisscross the cell– Microtubules: give cell

shape and movement of organelles

– Intermediate filaments: cell strength

– Microfilaments: enable cells to move and divide, help muscle contract and relax

Cell Components: cytoplasm• Fills space between

the nucleus and the cell membrane

• Fluid portion called cytosol and consist mostly of water

Cell organelles: nucleus• Function: storehouse

for most of the genetic information or DNA

• Composed of: DNA enclosed in a double membrane called the nuclear envelope, has pores (holes) to allow large molecules to pass between nucleus and cytoplasm

• Also contains nucleolus that is where ribosomes are assembled.

Cell organelles: Endoplasmic Reticulum (ER)

• Interconnected network of thin folded membranes

• Two types: – rough- studded with

ribosomes and responsible for protein assembly

– Smooth responsible for lipid assembly, break down of drugs and alcohol

Cell organelles: Ribosomes

Function: link amino acids together to form proteins (protein synthesis), made up of proteins and RNA

Some are found bound to the Rough ER, others are suspended in the cytoplasm

Cell organelles: Golgi Apparatus

– Function: process, sort and deliver proteins

– Also known as the UPS of the cell

Golgi

Cell organelles: Vesicles

– Function: small membrane bound sacs that isolate some materials from the rest of the cytoplasm and transport them from place to place in the cell

Cell organelles: Vacuoles

– Function: fluid filled sacs used for storage of water, food, ions and enzymes needed by the cell

– Central vacuole: found only in plants, takes up most of the space inside the cell to provide strength and support of the entire plant, may also contain other substances (some toxic)

Cell organelles: Mitochondria

– Function: supply energy to the cell, also known as power house of the cell

– Responsible for cellular respiration

– Unique in that it contains it’s own DNA and ribosomes

Cell organelles: Lysosome

– Function: contain enzymes that are used to defend the cell from invading viruses and bacteria, break down damaged or worn out cell parts

– Found in large numbers in animal cells

– Also known as the cleanup crew

Cell organelles: Centrioles / Centrosomes

– Function: organize microtubules to form cilia and flagella (used by cells for movement)

– Also used in cell division in animal cells, forming spindles

– Cilia-small hair-like projections that are used for movement and feeding

– Flagellum (-a) long whip-like structure that is used for movement

Cell organelles: Cell wall

– Function: rigid wall found outside of the cell membrane in plants, algae, fungi and most bacteria

– Used to protect, support and shape the cell

– Composition varies based on organism and it’s individual needs.

Cell organelles: Chloroplast

– Function: carry out photosynthesis in plants, algae and bacteria

– Contains chlorophyll that gives plants their green color

– Has it’s own DNA and ribosomes

Cell Transport: Cell membrane

• Cell membrane is composed of :

• Phospholipid bilayer: made up of 2 rows of phospholipids, heads (hydrophilic- like water) outside and tails (hydrophobic-water hating) on the inside

• Cholesterol molecules that provide strength to the cell

• Proteins: act as channels, and also act as support in cytoskeleton