• What tool made the discovery of the cell possible????
MICROSCOPES!!

• Schleiden: all plants were made of cells
• Schwann: all animals are made of cells
• Virchow: new cells can ONLY be produced from the division of existing cells

1. All living things are composed of cells
2. Cells are the basic units of structure and function in living things
3. All cells are produced from other cells

• Light microscopes allow viewing the cell but technology makes biologists pioneers….
– Confocal microscopy allows us to build 3d images of cells and their parts
– Video technology allow us to produce movies of cells at work
– Fluorescent tags allow us to follow molecules through the membrane
– SEM reveal details 1000 times smaller than the visible by the eye

Cells are the BASIC UNIT of structure and function in LIVING THINGS. Cells carry out all of an organism’s PROCESSES or FUNCTIONS.

• Cells are divided into TWO broad categories based on the presence of a NUCLEUS
– We will discuss organelles later but for now know that a NUCLEUS is a large membrane enclosed structure that contains a cell’s genetic material
NUCLEUS: Contains the cell’s DNA, has a membrane, controls cell’s activities

PRO: without or NO karyotic: kernel
Cells that lack a MEMBRANE BOUND NUCLEUS are called prokaryotic cells. They are SMALLER
AND SIMPLER than eukaryotic cells.
Prokaryotic cell: no nucleus, small, simple

• The genetic material is a single loop of DNA referred to as a NUCLEOID
• DNA can also be found on a circular loop called a PLASMID

• The best example of a prokaryotic cell is BACTERIA
• They can grow, reproduce, respond, and move

karyotic: kernel EU: true
Eukaryotic cells are LARGER AND MORE COMPLEX than prokaryotic cells. Eukaryotic cells have a
MEMBRANE BOUND NUCLEUS as well as many membrane bound STRUCTURES CALLED
ORGANELLES.
EUKARYOTIC CELL: large, complex, nucleus and organelles

• A eukaryotic cell’s nucleus is membrane bound keeping the genetic material separated from the rest of the cell
Some eukaryotes are single celled but others are large, multicellular organisms
Plants
Animals
Fungi
Protists

UNI: one
Unicellular organisms are ORGANISMS that have one CELL. They are divided into two different types.
• PROKARYOTES have cells with no NUCLEUS and a simple cell structure.
• EUKARYOTES have a NUCLEUS and a more complex cell structure.

MULTI: many
Multicellular organisms are ORGANISMS with more than one CELL. This is the case for most
ANIMALS and PLANTS that can be seen
(without the use of a MICROSCOPE.)

Cell -> Tissue -> Organ -> Organism
Tissue: a collection of connected CELLS that perform a similar function within an
ORGANISM. Tissue cells have the SAME
ORIGIN, STRUCTURE AND FUNCTION. The
CELLS look the same or almost the same. The work the cells do is also the SAME OR ALMOST
THE SAME.

Organs are made up of more than one kind of
TISSUE joined TOGETHER to perform a function.
An organism is any LIVING SYSTEM, either unicellular or multicellular and has the
CHARACTERISTICS OF LIFE.

• Organelle - Tiny structures INSIDE THE CELL are called organelles. They carry out specific
FUNCTIONS within the cell.
• “little organs”
• 1970 Lynn Margulis proposes the idea that these were actually once free living cells that were absorbed and used by a larger cell
ORGANELLE: inside the cell, carry out specific jobs

• Eukaryotic Cells include BOTH plants and animals.
– There are some organelles that are specialized in a plant or ONLY found in a plant. Be sure to make note of these organelles as we learn them.

• Divided into TWO major parts:
– The CYTOPLASM
– the NUCLEUS

• Homogenous, jelly like substance made of
CYTOSOL and the ORGANELLES (except the nucleus)
• CYTOSOL is made of water, salts, organic molecules and enzymes

• Control center of the cell
• Contains DNA
• Surrounded by the
NUCLEAR ENVELOPE
• Usually the easiest organelle to see under a microscope
• Usually one per cell
• Contains nucleoplasm

• This is NOT a structure, just a visible region
• Composed of ribosomal proteins and rRNA
• Ribosomes are assembled HERE!

• Double membrane bag that surrounds nucleus
• Outer membrane
• Inner membrane
• Contains nuclear pores
• Nuclear pores are place of selective transport between cytoplasm and inside of nucleus (proteins, mRNA)

• Outer membrane is continuous with the rough endoplasmic reticulum
(ER) and has ribosomes attached
• The space between the outer and inner membranes is continuous with rough endoplasmic reticulum space

• A.k.a. “ER”
• Connected to nuclear envelope
• Extensive network of membranes, “Highway of the cell”
• The passageways carry
PROTEINS and other materials from one part of the cell to another.

– The ROUGH endoplasmic reticulum has ribosomes to synthesize PROTEINS or transport them within or out of the cell.
– The SMOOTH endoplasmic reticulum does not have ribosomes and builds lipids and steroids.

• Site of protein synthesis
• Found attached to rough ER or floating free in cytosol
• Produced in a part of the nucleus called the nucleolus
That looks familiar…what is a polypeptide ?

– Ribosomes are the “factory” of the cell
– Ribosomes are small particles of RNA and protein found in the cytoplasm and on the endoplasmic reticulum
– Cells that are active in protein synthesis will have many ribosomes
– Proteins made on the endoplasmic reticulum will be transported to Golgi bodies.

• Looks like a stack of plates
• Golgi bodies receive
PROTEINS and other materials from the ER, package them and distribute them to other parts of the cell or outside the cell.
• Molecules transported to and from the Golgi by means of vesicles

Small round sacs that contain
ENZYMES that breaks down materials such as food and old CELL
PARTS that can be used again.

– Digest harmful bacteria to protect cell
– Recycling center for organelles

• “Powerhouse of the cell” because they convert ENERGY in food molecules to ENERGY the cell can use to carry out function.
• Cellular respiration occurs here to release energy for the cell to use
• Bound by a double membrane
• Has its own strand of
DNA

• Found only in plant cells
• Contains the green pigment chlorophyll
• Chloroplasts capture
ENERGY from the sun and use it to produce
FOOD for the cell.
• Bound by a double membrane

• Mitochondria (and chloroplasts) are thought to have originated as symbiotic, aerobic bacteria “swallowed” by the cell

• Large central vacuole usually in plant cells
• Many smaller vacuoles in animal cells
• Storage container for water, food, enzymes , wastes, pigments, etc.
What type of microscope may have been used to take this picture?

• Acts as skeleton and muscle
• Provides shape and structure
• Helps move organelles around the cell
• Made of three types of filaments

• Aids in cell division
• Usually found only in animal cells
• Made of microtubules

• Boundary of the cell
• Made of a phospholipid bilayer

• Found in plant and bacterial cells
• Rigid, protective barrier
• Located outside of the cell membrane
• Made of cellulose
( fiber )

• whiplike appendages
• Movement – either self movement or moving water across the membrane
• Composed of microtubules covered in a cell membrane
• Cilia
– Many small appendages
• Flagella
– 1 large appendage

Plant cells
• Cell Wall
• Cell Membrane
• Nucleus
• Nucleolus
• Mitochondria
• Endoplasmic reticulum
• Ribosomes
• Golgi Bodies
• Chloroplasts
• Vacuoles
• Lysosomes
Animal cells
• Cell Membrane
• Nucleus
• Nucleolus
• Mitochondria
• Endoplasmic reticulum
• Ribosomes
• Golgi Bodies
• Vacuoles
• Lysosomes