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UNIT I
Chapter 3
Sections 1 and 2
History of the first microscopes:
1. 1500’s- first lenses used by merchants to determine
quality of cloth (look at precision of the weave)
2. 1600’s- microscope and telescope constructed
Anton van Leeuuwenhoek- made simple
compound microscope and observed
living things in pond water for the first time
Robert Hooke- looked
at thin slice of cork.
Noticed it was made of
tiny empty chambers
and called them
“cells”
Hooke‟s work stimulated others to search for cells in
living things. It became apparent that cells were basic
units of all living things.
Matthias Schleiden- concluded all plants made of cells
Theodor Schwann- concluded all animals made of cells
Rudolf Virchow- Russian physician said “Where a cell
exists, there must have been a preexisting cell.”
What theory did this help to support?
The Theory of Biogenisis:
Life comes from other living things!
3 parts to the Cell Theory:
1. All living things are made of cells.
2. Cells are the basic units of structure
and function in all living things.
3. New cells are produced from
preexisting cells.
Cells come in many
shapes and sizes.
•Smallest cell = bacteria
•Largest cell = Ostrich egg and giant amoeba
Cells can be classified as either prokaryotic or
eukaryotic. What is the difference?
1. Prokaryotic cells have no nucleus and
membrane bound organelles.
•
Small and simple; Example: bacteria
•
Contain cell membrane, cytoplasm,
rribosomes and sometimes a cell wall.
2. Eukaryotic cells do have a
nucleus and membrane
bound organelles.
• Larger and more complex
• Examples: animal cells, plant
cells, fungal cells, and protists
Your body has special organs, like a heart, to keep your
body functioning to stay alive. Cells also have “organs”,
but we call them organelles.
What are organelles? Specialized structures found in
the cell that perform a distinct process within the cell.
Examples: Nucleus, ribosomes, mitochondria,
chloroplast, and etc.
Now let’s learn the parts of the cell!
Cell Membrane = thin, flexible barrier around the cell.
•Regulates what enters and exits the cell like a
“gate keeper”
•Provides protection and support
•Made of double-layered sheet called lipid bilayer
Phosphate glycerol head is
that is not soluble in water.
hydrophilic (water loving)
Lipid molecules
P
2 fatty acid tails are
hydrophobic (water fearing)
Water is found outside the cell and inside the cell,
but not in the cell membrane between the lipid
bilayer!
Cell Membrane is a “mosaic” of many different kinds of
molecules.
• Protein channels and pumps move materials through
the cell membrane
•Carbohydrate
molecules act
like “ID cards”
allowing cells to
communicate
with each other.
Cell Wall- strong layer around the cell membrane found
in plants, algae, fungi, and nearly all prokaryotes.
NOT found in animal cells!!!!
• Provides support and protection for the cell
• Made from fibers of carbohydrate (cellulose)
and proteins
Cytoplasm- jelly-like material inside the cell to
hold the organelles and maintain the cell‟s shape.
Nucleus- large structure only found in eukaryotic cells
that contains the cell‟s genetic material (DNA); the
control center of the cell, like a “brain”.
Parts of the cell nucleus:
• Nucleolus- small dense region in nucleus where
ribosomes are made
• Nuclear envelopedouble layer memb.
surrounding the
nucleus containing tiny
nuclear pores to allow
materials in &out.
DNA has 2 forms:
1.
Chromatin- Coiled DNA
bound to protein. Looks
like noodles
2. ChromosomesCondensed DNA that
looks like the letter “X”
Chromatin condenses into Chromosomes when cell
gets ready to divide during mitosis or meiosis. The
genetic material is passed from one generation to the
next.
•
Cytoskeleton- Network of protein filaments that
help the cell to maintain its shape and involved in
many forms of cell movement
• Made up of microtubules and microfilaments
1. Microtubules- serve as “tracks” along which
organelles are moved. Important in cell division- help
to separate chromosomes. Also form cilia and
flagella which allow cells to move.
2. Microfilaments- long,
thin fibers function in
movement and support
the cell
Ribosomes- makes proteins by linking amino acids
Endoplasmic Reticulum- interconnected network
of thin, folded membranes that produce,
process, and distribute proteins. The cell‟s
internal transport system.
There are 2 types
of ER:
1. Rough ER- (has
ribosomes
attached)
2. Smooth ER-(no
ribosomes
attached)
Golgi Apparatus- (Aka: Golgi Body or
Golgi complex) stack of flat, membraneenclosed spaces containing enzymes that
process, sort, and deliver proteins. It is
like the “post office” of the cell.
• Carbohydrates and
lipids attached to
proteins are “packaged”
• Proteins sent to final
destination
Lysosomes- organelles that contains enzymes to
break down food or waste within a cell. It is the
“clean-up” crew of the cell.
• Break down lipids, carbohydrates, proteins
from food particles (little “digestive sacs”)
• Break down „old‟ cell parts, removing debris
Vacuoles- organelle that is used to store materials,
such as water, food, or enzymes, that are needed
by the cell. It is like a storage “sac”
• Large in plant cells (single large vacuole)
• In animals, smaller vacuoles called vesicles.
They transport substances within the cell.
Vesicle
Chloroplasts- organelle made up of numerous
membranes that are used to convert solar energy
into chemical energy (glucose); contains
chlorophyll. Found in plants and some other
organisms (none found in animals and fungi)
• Produce energy-rich food molecules from
sunlight by photosynthesis
• Green pigment- chlorophyll found in
photosynthetic membranes to absorb sun
Mitochondria- bean shaped organelle that supplies
energy to the cell and has its own ribosomes and
DNA. The "Powerhouse of cells” found in nearly
all eukaryotic cells
• Use energy from food to power growth,
development and movement
• Cells that require more energy have more
mitochondria
Organelle DNA- DNA found in mitochondria and
chloroplasts. Essential for normal function of both
organelles.
Theory of Endosymbiosis proposed by Lynn Margulis:
• A theory to explain how simple prokaryotic single
cell organisms become complex eukaryotic
multicellular organisms.
•
Prokaryotic cell got hungry and ingested another
prokaryotic cell “cell cannibalism”. The ingested contents
did not completely digest. Those undigested particles
developed into sophisticated organelles like chloroplast and
mitochondria and the cell became eukaryotic. Now the cell
doesn‟t have to rely only on eating other cells for energy.
The cell can simply photosynthesize. From here, life
became more complex.