CELLS: THE BASIC UNIT OF LIFE
Some Cell Fun Facts You can grow heart cells in a petri dish. Humans have an estimated 10 trillion cells. The largest known cell is an unfertilized ostrich egg cell. The word cell comes from the Latin word cellula, meaning, “small room”. One single cell contains two meters of DNA. Humans shed and re-grow outer skin cells about every 27 days.
Cells Discovered in 1665 Why didn’t we know about cells before this?
Robert Hooke’s microscope:
Section One: The Diversity of Cells Part 1:The Discovery of Cells 1665
Robert Hooke First person to describe cells Also looked at feathers, fish scales, and eyeballs of house flies Mostly looked at plants and fungi (these things have cell walls)- makes them easy to see
SAW “ANIMALCULES” IN POND SCUM 1673 ANTON van LEEUWENHOEK Found cells in other organisms…. SAW “ANIMALCULES” IN POND SCUM ALSO SAW BLOOD CELLS AND BACTERIA for the first time
200 Years Later…
1838 Matthias Schleiden, a German scientist said….all plant parts are made of cells One year later, Theodor Schwann, a German scientist that studied animals stated that all animal tissues are made of cells
1858 Rudolf Virschow Said that all cells form only from other cells
THE CELL THEORY: 1. ALL ORGANISMS ARE ONE OR MORE CELLS 2. CELL IS THE UNIT OF ALL LIFE 3. All cells come from existing cells
4 Parts found in all Cells 1. Cell membrane-outer covering 2. Organelles- small bodies in the cytoplasm 3. DNA (genetic material) 4. Cytoplasm- the fluid inside a cell along with all the cell’s contents Small size Smallest=bacteria Largest=ostrich egg how big animation All cells have a …
Two Kinds of Cells: 1. Cells without a nucleus 2. Cells with a nucleus Called Prokaryotic cells These can be either: bacteria or archaea Are super small in size 2. Cells with a nucleus Called Eukaryotes- (these are the cells in plants, animals and fungi)
PROKARYOTIC CELLS Bacteria, and Archaea NO NUCLEUS NO MEMBRANES AROUND ORGANELLES CIRCULAR DNA (looks a little like a rubber band)
Bacteria Most common prokaryotes Smallest cells known Live almost everywhere No nucleus but DO have DNA DNA is long and shaped like a twisted rubber band (circular shaped) No membrane-covered organelles Do have ribosomes and cell wall
Brainpop
Archaea… Same as bacteria except: Ribosomes are different…..are more like Eukaryotic ribosomes Cell wall and cell membranes are made of different materials Many live in Bizarre environments! Ex. heat-loving, salt-loving, methane-making archaea
SURFACE TO VOLUME RATIO: ORGANISMS NEED SMALL CELLS TO KEEP THE RIGHT SURFACE TO VOLUME RATIO IF A CELL GROWS TOO BIG, THERE WON’T BE ENOUGH OPENINGS IN THE SURFACE TO LET MATERIALS IN AND OUT !
EUKARYOTIC CELLS(our cells) (ALL CELLS) EXCEPT bacteria and Archaea Are 10 times bigger than bacteria Have a NUCLEUS Have MEMBRANE –COVERED ORGANELLES Have LINEAR DNA found inside a nucleus
Really important cell vocab: CELLULOSE- tough stuff in plant cell walls ATP- the “energy molecule” for a cell, (is like gasoline for a car) DNA- instructions for the cell PHOSPHOLIPIDS- the stuff all membranes are made of
Section 2 The Inside of a Eukaryotic Cell The “true” cell. plants animals fungi
Cell wall ribosome Mitochondrion plural=mitochondria Golgi Complex Fluency Chart… Cell wall ribosome Mitochondrion plural=mitochondria Golgi Complex vesicle Cell membrane lysosome E.R. Endoplasmic reticulum
Plant Cells Video:
CELL WALL IN PLANT CELLS (and algae) ONLY Made of a hard material called Cellulose Provides strength and support to the cell membrane When you look at dried hay, sticks and wooden boards you are seeing the cell walls of dead plant cells!
PLANT CELL WALL PICTURES:
CELL MEMBRANE All cells are covered by this Is formed by phospholipid molecules Allows nutrients in Allows waste products out:
Cytoskeleton A web of proteins in the cytoplasm that acts as a muscle and a skeleton. It helps a cell retain its shape and moves organelles around.
NUCLEUS: Library, or Town center Stores the DNA Has all the “secret info” for the organism
RIBOSOMES: SMALLEST of all ORGANELLES (THE DOTS) ON THE E.R. (only organelle without a membrane) Act like factories for making proteins
MITOCHONDRIA: Power plants…release energy for the cell Make the ATP Used in all cell ( activities)
VACUOLE: Is really big in plant cells Small in animal cells Serves as a water storage compartment
CHLOROPLASTS:(plant cells only!) Contains chlorophyll Captures sunlight to make food (sugar) used by mitochondria Makes plants appear green
GOLGI COMPLEX: FedEx Delivery Gets rid of things inside the cell Shipping and Handling
LYSOSOMES: "suicide sacs" Contain digestive enzymes Cellular Digestion… LYSOSOMES: "suicide sacs" Contain digestive enzymes Clean-up/ destroy cell waste, sometimes called the recycling center Can act as security to protect the cell from invaders Sanitation company? Mainly in animal cells
ENDOPLASMIC RETICULUM (ER) Post office, delivery system, tunnel system Makes lipids for membranes, processes and transports proteins CELL: ER
Cytoplasm
VESICLES: Membrane –covered compartments inside the cell
Animal cells: human cheek cells
Another Fun Fact... EVIDENCE? Scientists believe that mitochondria and chloroplasts originated as a prokaryotic cell that was “eaten” by larger cells. They ended up surviving inside. EVIDENCE? Both have two membranes Have a) ribosomes and b) circular DNA Same size as bacteria Divide like bacteria
Sec.3: The Organization of Living Things… (Small to big) CELLS TISSUES ORGANS ORGAN SYSTEMS ORGANISM
Organism Anything that can perform life processes by itself Organisms can be: Unicellular-(single celled) Multicellular- (consists of many cells) Euglena:
Oh the Joy of being multicellular ! Larger size Longer life Specialization Each type of cell has a special job Makes the organism more efficient
Structure and Function In an organism, structure and function are related. Example: Alveoli air sacs in the lungs: See fig. 4 p.79
End of Ch 3 Cells: The Basic Units of Life