CELLS
CELL DISCOVERY
•In 1665 Robert Hooke used a micro scope to
examine a small piece of cork (remains of
dead plant cells)
•Cell means ‘small boxes’
•Anton Van Leeuwenhoek was the first to
observe living cells.
CELL THEORY
•All living things are composed of one or more cells
•Cells are the basic units of structure and function in
an organism
•Cells come only from the reproduction of existing
cells.
PROKARYOTES
•Unicellular
•No membrane- covered organelles
•No nucleus
•Circular DNA
•Bacteria
EUKARYOTES
•Cells that contain a membrane bound nucleus and
other organells
•DNA in the nucleus
•Linear DNA
•Animals, Plants, Protists, and Fungi
PROKARYOTIC CELL
EUKARYOTIC CELL
PARTS OF A EUKARYOTIC CELLS
•Cell Membrane
•Allows nutrients and other materials in and wastes out
•Selectively Permeable- only allows certain things in or out
•Primarily made up of proteins and lipids
•Phospholipids- one of the major types of lipids in the cell
membrane (made of a head and two nonpolar tails)
(head close to water, tail away from water)
•Phospholipid Bi-Layer- double layer of phospholipids
PHOSPHOLIPID BI-LAYER
PARTS OF CELL CONT.
•Cytoplasm- fluid (Cytosol) and organelles that
make up the inside of the cell
NUCLEUS
•Stores heredity information in its DNA ( Chromatin)
•Site where RNA is copied from DNA
•Surrounded by the nuclear envelope
•Contains the Nucleolus (site where ribosomes are
synthesized and partially assembled)
MITOCHONDRIA
•‘Power House’
•Large organelles where chemical reactions transfer
energy from organic compounds to ATP (Ex: the food
you eat into energy for cells)
•More numerous in cells that have high energy requirement
(ex: muscles, liver ect)
•Contain their own DNA
•Cristae-large folds inside the mitochondria where the
chemical reactions occur.
RIBOSOMES
•Made of two parts- proteins and RNA
•Most numerous organelle
•Not membrane bound
•Produces protein
•Both free (protein used in the cytosol) and attached
to the Rough ER.
ENDOPLASMIC RETICULUM (ER)
•Intercellular highway (path along which molecules
move from one part of the cell to another)
•Two types of ER
•Rough ER- produces protein to be exported from the cell
or inserted into the cell membrane (ribosomes attached to
the outside)
•Smooth ER- synthesizes steroids, regulates calcium levels,
and breaks down toxic substances (no ribosomes)
GOLGI APPARATUS
•Processes, packages, and secretes proteins for
export from the cell.
•Appears to be a series of flattened sacks
LYSOSOMES
•Contain enzymes that break down and help recycle
large proteins in animal cells
•Selectively destroys tissue (ex: tadpoles tail, tissue
between your fingers)
CYTOSKELETON
•Structure that maintains the shape and size of the
cell
•Two major components:
•Microfilaments- threads made of a protein called Actin
(small strands)
•Microtubules- large strands that provide support for the
cell and aide in the division of the cell (spindle fibers)
MICROFILAMENTS AND MICROTUBULES
CILIA AND FLAGELLA
•Hair like organelles that extend from the surface of
the cell, where they assist in the movement of the
cell.
MORE PARTS OF THE CELL
•Vacuole- stores enzymes and waste products
•Cell Wall- supports and protects the cell (in plants,
not animals)
•Chloroplast- (plastid) stores food or pigments
transfers energy from light to organic compounds (in
plants not animals)
•Centrioles: aid in cell division