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Intro to the cell
I. Cells
A. Smallest unit of matter that can carry on
all processes of life
B. 1665 – Robert Hooke – (Published
Micrographia)
1. Coined term “cell”
C. Leeuwenhoek - single-celled organisms
1. Improved microscope
II. Cell Theory
A. Schleiden, Schwann, and Virchow
1. All organisms are made of cells.
2. All existing cells are produced by other living
cells.
3. The cell is the most basic unit of life.
Prokaryotes
Unicellular
Small cells
Eukaryotes
Mostly multicellular;
sometimes unicellular
Larger Cells
No nucleus or membranebound organelles
Nucleus with membranebound organelles
DNA in cytoplasm
DNA found in Nucleus
Circular DNA
Linear DNA
Reproduce Asexually
Cell division by binary
fission
Reproduce asexually and
sexually
Cell division by mitosis and
meiosis
EX: Bacteria, blue-green
algae
EX: Protists, Plants,
Animals, Fungi
III. Basic info
A. Organelles: cell component that performs
specific functions
B. Prokaryote: unicellular organisms lacking
a membrane-bound nucleus; circular
DNA
C. Eukaryote: membrane-bound nucleus
with chromosomes containing genetic
info
Cell Parts
I. Cell Membrane
A. Surrounds the cell and controls what
comes in & out (selectively permeable)
B. A bilayer of phospholipids with
imbedded proteins.
– Polar “head” with two nonpolar “tails”
Cell Membrane cont..
C. All materials that enter and leave the
cell must pass through the membrane.
– 1. food
– 2. wastes
II. Size limitations on cells
A. The greater the distance from the
middle of the cell, the longer it takes to
transport stuff.
B. As a cell grows, the volume grows
faster than the surface area.
C. Cells must maintain a large surface
area to volume ratio to feed itself fast
enough.
III. Cytoplasm
A. Between cell membrane and nucleus
B. Cytosol (liquid) + organelles
IV. Nucleus
A. Nuclear membrane – double
membrane that separates DNA from the
cytoplasm.
B. Nucleolus- Dark patch in the nucleusinvolved in the production of ribosomes.
C. Chromatin- Form that DNA takes
when the cell is not dividing.
D. Nuclear pores- allow materials to
pass.
V. Mitochondria
A. Site of cell respiration
B. Folded inner membrane called cristae
increase surface area to increase the the
amount of ATP produced.
C. Has its own bacteria-like DNA and
ribosomes and is about the size of aerobic
bacteria.
VI. Ribosomes
A. Site of protein synthesis.
B. Eukaryotic ribos are larger than
Prokaryotic ribos.
C. Some are “free” and floating in the
cytoplasm.
D. Others are “bound” to the ER.
VII. Endoplasmic Reticulum
A. Rough- Series of tubes that transport
proteins that are to be shipped out of the
cell.
B. Smooth- Series of tubes that produce
streroids and helps detoxify some poisons
and wastes.
VIII. Golgi Bodies
A. Recieves vesicles from Rough ER with
proteins.
B. Finishes the packaging and/ or
construction of cell products and then
sends them on toward the cell membrane.
IX. Lysosome
A. Bubble like vesicle with hydrolytic
enzymes.
B. Breaks down food, old cell parts etc…
X. Vacuoles
A. In animals, small storage vesicles for
food, wastes, etc..
B. In Plants, one large vacuole fills with
water in the middle of the cell.
– 1. the pressure from this water pushes the
cytoplasm against the cell walls. This gives
the cell added strength.
XI. Plastids
A. Cloroplasts: contains chlorophyll,
photosynthesis occurs here
– 1. Like the Mitochondria, they have their own
DNA, Ribos. Similar in size and shape to
cyanobacteria.
B. Amyloplasts - store starch
C. Chromoplasts- Hold pigments- yellow
to red.
XI. Cell Wall
A. Surrounds and supports plant cells
only!
B. Made of cellulose
C. Bacterial cells have cell walls made of
different sugars.
PRESSURE vessel: prevent
overextension when water enters
XIII. Cytoskeleton
A. Runs through cells, helps animal cells
maintain shape.
B. Involved with movement inside and
outside the cell.
Microtubules (large) involved in cell
division.
Microfilaments (small) cytoplasmic
streaming and movement of muscles.
XIV. Cilia and flagella
A. Movement of cells or material around
cells.
B. Cilia – small & numerous: paramecia,
cells of the respiratory tract.
C. Flagella- large & few: sperm, euglena
XV. Centrioles
A. Made of microtubles, associated with
mitosis in animals.
B. Not found in plants.