Download UNIT 2 PART 1 THE CELL

UNIT 2 PART 1: THE CELL
ALL LIFE PROCESSES ARE CARRIED
OUT BY CELLS WHETHER THE
ORGANISM HAS ONLY ONE CELL OR
MANY CELLS.
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THE CELL THEORY
• All organisms are made of one or more cells
and the products of those cells.
• All cells carry on life activities.
• New cells only come from other living cells by
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the process of cell division.
Organization
Organisms can have only one cell
(unicellular) or many cells (multicellular).
In multicellular organisms the cells are
specialized and can not live on their own.
Each cell carries out only some of the
necessary life functions and depends on
all the other types of cells.
This requires organization and energy.
ORGANIZATION
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Levels of Organization
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Biosphere
Ecosystem
Community
Population
Organism
Organ
systems
Organs
Tissues
Cells
Molecules
Atoms
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Parts of a Cell:
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CELL (PLASMA) MEMBRANE
NUCLEAR MEMBRANE
NUCLEUS
NUCLEOLUS
CYTOPLASM
ENDOPLASMIC RETICULUM
RIBOSOME
GOLGI BODY
VACUOLE
MITOCHONDRIA
MICROTUBULES
MICROFILAMENTS
CILIA AND FLAGELLA
THESE ARE ONLY IN
ANIMAL CELLS:
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LYSOSOME
CENTRIOLES
THESE ARE ONLY IN
PLANT CELLS AND
SOME BACTERIA:
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PLASTIDS (CHLOROPLAST)
CELL WALL
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Plasma (cell) Membrane
• The plasma membrane
separates the cell from
its environment.
• It regulates movement
of materials in and out
of the cell.
• Maintains homeostasis
• Homeostasis –
maintaining a constant
internal environment.
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Cell Membrane Structure
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A fluid-mosaic of phospholipids and proteins.
Phospholipids form a thin, double layer that is a
barrier to many other molecules.
Proteins float within the lipid bilayer & perform a
variety of jobs:
a. Transport channels
b. Enzymes
c. Receptors
d. Identity markers
e. Adhesives
f. Cytoskeleton
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Diffusion
• The movement of molecules
from a region of high
concentration to a region of
low.
• The difference between the
high and low concentrations
is called the concentration
gradient.
• Diffusion is a type of passive
transport: it does not cost
the cell any energy.
– Ex: perfume
• Some molecules get help
across: facilitated diffusion
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Osmosis
• Osmosis is the diffusion of water across a membrane
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Active Transport
• Active transport uses energy (ATP) to move molecules
against the concentration gradient from low to high
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Nucleus &
Nucleolus
• The nucleus is
surrounded by a nuclear
membrane.
• The nucleus controls all
activities of the cell.
• The nucleus contains
chromosomes that are
made of DNA.
• The nucleolus makes
RNA and ribosomes
needed for protein
synthesis.
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Nuclear Membrane
• The nucleus is encased by a double membrane.
• The nuclear membrane is full of pores that let
RNA and ribosomes pass through it.
• The membrane forms the ER, lysosomes &
golgi body.
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Cytoplasm
• The jellylike stuff inside
the cell
• It acts as a solvent
• Many biochemical
reactions take place
here
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Endoplasmic Reticulum
• Membrane bound, fluid-filled canals that form a continuous
network with one extremely large enclosed space
• Manufactures, processes, and transports molecules used in
and out of the cell
• Rough ER has
ribosomes on it
• Smooth ER has no
ribosomes
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Ribosomes
• Site of protein
synthesis
• Made of RNA from
nucleolus
• May be on Rough
ER or free in
cytoplasm
• Not surrounded by a
membrane
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Golgi Bodies
• Form from bubbles off of
the ER (like a lava lamp)
• Bubbles join into
flattened sacs, making a
‘stack of sacs’
• Synthesize, package &
secrete cellular products
for use in the cell or
export
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Lysosomes
• Formed from the Golgi body, this membrane
bound sack contains digestive enzymes, like a
stomach.
Food Vacuole
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Vacuole
• Membrane bound
space that contains
V
V
CV
– Food
– Water
– Waste
• Contractile vacuole
pumps water out of
the cell
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Mitochondria
• Site of aerobic
cellular respiration
– Provides energy for
the cell to use
– Converts energy
stored in food to ATP
• Double membrane
bound organelle
– Outer smooth
– Inner folded
• Bacteria-like
structure
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MICROTUBULES AND
MICROFILAMENTS
• MICROTUBULES
– Long, hollow cylindrical
structures
– Cell skeleton
– Found in centrioles, cilia,
flagella
• MICROFILAMENTS
– Threadlike strands
– Cytoplasmic streaming
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Centrioles
• Two found in
animal cell
cytoplasm near the
nucleus
• Function in cell
division
• Make spindle
fibers
• Cylinder of 9
triplets of
microtubules
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Cilia &
Flagella
• Used in
locomotion &
feeding
– Flagella: 1 long
whip
– Cilia: Many
small hairs
• Similar in
structure to
centrioles
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Chloroplast
• Site of photosynthesis
– Captures light energy
– Makes food (sugar)
• Double membrane
bound organelle similar
to mitochondria
– Inner membranes are
arranged into stacks
called grana
– Grana contain
Chlorophyll
• Bacteria-like structure
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CELL WALL
• FOUND ONLY IN
PLANTS AND
BACTERIA
• FOR SUPPORT
AND
PROTECTION
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