Transcript History of Cell Discovery

History of Cell Discovery
Chapter 4
Microscope view of cells
► Robert
Hooke – first to see cells!
 designed microscope that he was
able to view cork cells with (1665).
►Named “Cells” because
they look like monk quarters
Cells with stone beds
Microscope view of cells
Anton Van Leeuwenhoek – first to see living
cells.
► improved design, and was
able to view red blood cells
and bacteria.
 Called them "animalicules"
Scientists of Cell Theory
► Theodore
Schwann – zoologist who
observed that the tissues of animals had
cells (1839)
Scientists of Cell Theory
► Mattias
Schleiden – botanist who observed
that the tissues of plants had cells (1845)
Scientists of Cell Theory
► Rudolf
Virchow – reported that every living
thing is made up of cells, and that these
cells must come from other cells.
Cell Theory
1.
All living things are made of one or more
cells.
2. Cells are the basic unit of structure and
function in organisms.

(the smallest unit that can perform life
functions)
3. All cells come from pre - existing cells.
Terms
► Cell
– the smallest unit that can
carry on the processes of life.
► Unicellular
cell
– consists of only one
► Multicellular
– consists of more
than one cell
Basic cell Structures
► Cell
Membrane –
outer boundary
► Nucleus – control
center
► Cytoplasm – stuff
between membrane
& nucleus
Two Basic Cell Types
►Prokaryotic
– lacks internal organelles.
 Has a cell membrane & a cell wall
 Has NO nucleus.
►Means
“before the nucleus”
 Usually Unicellular organisms
 Ex: Bacteria
Two Basic Cell Types
►Eukaryotic
– contains organelles.
 Has a nucleus
 Has a cell membrane
 Usually multicellular organisms
 Ex: Plants, animals, and protists
The First Cells & Their
Environment
The First Cells
► Environment
during time of first cells:
 No oxygen
The first cells were:
 Anaerobic (Does not use oxygen)
 Prokaryotic (Cells that have no nucleus)
 Heterotrophic (Consumers)
The First Cells
► The
first autotrophs (make own food) used
chemosynthesis (gives off CO2).
► Around
3 billion years ago, photosynthetic
life had began (gives off O2).
► This
production of oxygen was the start of
aerobic organisms (use O2 to produce
energy
Endosymbiosis
Eukaryotes evolved from a mutually beneficial
relationship with prokaryotes.
 Endosymbiosis – Eukaryotic cells engulf
prokaryotic cells. Prokaryotic cells then
performed beneficial actions inside the
eukaryotes while eukaryotes provided a safe
environment for the prokaryotes.
Spontaneous Generation
► Before
the 17th century, people believed
that living things could come from nonliving
things.
 The Cell Theory has not been written.
Example: Rotting meat
►
Maggot
Biogenesis – Living things come from other living
things
Redi’s Experiment
► Control
group – Uncovered jar that
contained meat
► Experimental group – Netting-covered jar
 Allowed air to enter and prevented flies from
landing on meat
► Results:
Maggots seen in jar without
netting, but not seen in jar with netting
Pasteur’s Experiment
► The
invention of microscopes allowed
people to discover microorganisms.
► People believed these microorganisms
developed spontaneously from the air.
► Louis Pasteur created an experiment where
broth from boiled meat was placed in a
curve-necked flask.
 Air could enter through the neck, but solid
particles could not.
Pasteur’s Experiment: Cont’d
Results
►
►
Broth boiled inside the flask
remained clear for one year.
After necks were broken off,
broth became cloudy and
contaminated with
microorganisms after one day.
Conclusion
►
Microorganisms come from
other microorganisms (NO
SPONTANEOUS GENERATION)