Download The Cell

The Cell
Cell Anatomy: Parts and
Function
Animal Cell
• Basic teaching tool
• 2-D Drawing, in real life, cells are 3-D
• In real cell, not all organelles would be
present (depending on type of cell)
• Some organelles would cover others,
so we wouldn’t be able to see every
single organelle
Cell Membrane (not an organelle)
• Function: Provides shape and flexibility
Moves materials and waste
products into and out of cell
• Selectively Permeable- allows certain
substances to cross into cell easily and
blocks others from entering at all
Cell Membrane
• Once thought that the cell membrane was
stationary, now due to advancements in
technology (SEM) determined that the cell
membrane is constantly moving/changing,
this is known as the fluid mosaic model.
• Example of flexibility: RBC is too big for
capillary but can still squeeze through
Cytoplasm (not an organelle)
• (Protoplasm, Cytosol)
• Found between cell membrane and
nucleus (contributes to shape and
flexibility)
• Mostly water (aqueous solution) in which
organelles are found/bathed
Cytoplasm
• In this solution, there are some proteins,
amino acids, carbohydrates and dissolved
salts
• Also serves as temporary storage site of
raw materials
• Used to transport materials from one part
of the cell to another
Ribosomes
**Site of Protein Synthesis**
• Most numerous organelle in many cells
• Composed of RNA and protein molecular
constituents
2 Types of Ribosomes
• Cytoplasmic
• (found in cytosol)
• makes proteins used
within cell (ex: repair
proteins)
• Endoplasmic
• (attached to
endoplasmic
reticulum)
• makes proteins that
will be exported (ex:
insulin)
Lysosomes
*Only found in animal cells
• Phospholipid/protein membrane bound
organelle
• produced by the Golgi Apparatus and
contain digestive enzymes
• “garbage disposal unit” of the cell  clears
out unnecessary or broken parts
Lysosomes
• Function determined by the type of cell
• Ex: White Blood Cells can ingest invading
bacteria thereby protecting you and
providing nourishment for the WBC
Endoplasmic Reticulum (ER)
• Phospholipid/protein membrane
* Stretches throughout cytoplasm*
• System of folds, sacs, tunnels “Highway
System of the Cell”
• Efficiently moves materials safely through
cell (enzymes in cytoplasm could
damage), or can be used for temporary
storage
2 Types of ER
Rough ER
(ribosomes attached)
-found in cells that
export lots of proteins
Smooth ER
(no ribosomes attached)
-can produce lipids,
helps break down
toxins in liver
Golgi Apparatus (Complex, Body)
• phospholipid/protein membranes more a
stacking of tunnels
• sections are not connected (membranes
between each)
• “Post Office/Shipping Dept.” of cell 
Anything leaving cell goes through Golgi
Golgi Complex
**processing, packaging, secreting organelle
• Assembly line, works closely with the ER,
and modifies proteins for export by the cell
• Also makes lysosomes in animal cells
Cytoskeleton
• Function: Support structure that maintains
shape and size of cell
• Participates in movement of organelles in
cytosol
• Network of long protein strands in cytosol
• Can be assembled and disassembled quickly
(when cytoskeleton is absent, cell just rolls or
flows
• Ex: WBC when it engulfs bacteria,
disassembles cytoskeleton
2 Components of Cytoskeleton
Microfilaments
-small, solid threads of
protein that contribute
to cell movement
Microtubules
-larger, hollow tubes of
protein
Nucleus
• “Brain, Boss” of cell
• Function: Main control center of cell
• Surrounded by double membrane called nuclear
envelope
• Contains fine strands of chromatin
• Chromatin- combination of DNA and protein
-contains genetic information in DNA
• DNA also contains information on how to build
and run cell
Nucleus
• Site where RNA is copied from DNA then
transported through nuclear pores to cytosol
where it can direct protein synthesis
• nuclear pores- small holes in nuclear envelope
• most nuclei also contain at least one nucleolus
• nucleolus- spherical area, site where ribosomes
are synthesized and partially assembled before
they pass through the nuclear pores to the
cytoplasm
• some cells have more than one nucleoli
Mitochondria
“Powerhouse of cell”
• Function: site of chemical reactions that convert
energy from organic molecules (lipids,
carbohydrates, proteins) to ATP (the usable form
of cellular energy for most cells)
• large, bean-shaped organelle
• usually more numerous in cells with high energy
requirements (i.e. liver cells and muscle cells)
*can be as many as 2500 mitochondria in each
liver cell*
Mitochondria
• Have own DNA and only produce new
mitochondria when old ones grow and
divide
Cilia and Flagella
* NEVER BOTH FOUND ON THE SAME
CELL *
**Only found in animal cells
• made of microtubules (protein)
Cilia
• Cilia- small, hair-like organelles, present in
large numbers
• Cells lining the respiratory tract contain
cilia that trap particles and debris from air
we inhale.
• As they move, the cilia sweep the trapped
materials back up to throat where they are
removed when you swallow.
Flagella
• Flagella- (flagellum is singular) longer and
less numerous than cilia
• Function in moving unicellular organisms
from place to place or in moving
specialized cells (i.e. sperm cells)
Cilia and Flagella
• Both cilia and flagella have a similar
internal structure: Both are composed of 9
pairs of microtubules arranged around a
central pair
Cell Wall
-Rigid structure (supports and protects plant)
-Prevents expansion when excess H20
enters cell
-Protects against pathogens and
environment
-Store of carbohydrates
Cell Wall
• Older cell is, thicker cell wall will be
• Completely impermeable except where
pores are
• Composed of cellulose and pectin
Vacuoles
• Store enzymes and metabolic wastes
• Get larger with age
• Large organelles (up to 90% of cell’s
volume)
• Some wastes are toxic and must be kept
away from rest of cell
Vacuoles
• Other things stored in vacuoles:
Poisons- acacia trees
Water- cactus
Waste materials- onions
Plastids
• Surrounded by 2 membranes (like nucleus
and mitochondria)
• Thought to be own organism and joined
with other cells in symbiotic relationship
• Can replicate themselves
3 Types of Plastids
1. Chloroplast- produce and store
chlorophyll
-Site of photosynthesis
-Have own DNA
3 Types of Plastids
2. Chromoplast- produce and store other
photosynthetic pigments (carotenes,
xanthophylls)
-Help photosynthesize other wavelengths of
light
-Petals of flowers and fruits contain
chromoplasts
3 Types of Plastids
3. Leukoplast- colorless plastid
-Store “food” anything that can be
converted to energy by mitochondria
Ex: Potatoes have lots of leukoplasts– store
starch