Transcript Cells - Mrs. GM Biology 200

Unit 3: The Cell & Its
Environment
Ch 5: Inside The Cell
Structure of Cells
• 3-D, not 2-D
–spheres, cubes,
or bricks
–Many can change
shape
–Some have
spikes, bulges,
or other strange
extensions
Sizes of Cells
• Vary in size
–Some < ½ µm
• (1 µm = 1/1000 mm
or 1/1,000,000 m)
–bacteria among the
smallest
–egg cells among the
largest
Why is there a limit to cell growth?
2 Main Types of Organisms
• Unicellular
Organisms
•Multicellular
Organisms
–Single cell
–Many cells
•Carry out all
processes in
one cell
–Ex. amoeba,
paramecium,
euglena
•Division of labor
–cells are
specialized
(specific functions)
–Ex. You, dog,
tree, elephant
Why can multicellular organisms be big
if there is a limit to cell size?
Organization Within Cells
• Why might cells need to be organized?
• How are they organized???
____________
Cell (Plasma) Membrane
• Surrounds each cell
– creates boundary between cell contents &
outside environment (including other cells)
• Acts as a gatekeeper
– selectively permeable
Cytoplasm
• Gel-like substance filling much of cell
– approx. 70% water
– Contains organelles
– Some chemical reactions
Two Major Types of Cells
• Prokaryotes
– No nucleus
• DNA  single
chromosome
– no mitosis
– no membranebound organelles
• Eukaryotes (You – karyote!)
– Nucleus
• DNA  multiple
chromosomes
– mitosis
– Membrane-bound
organelles
Two Major Types of Cells
Eukaryotic Cell Organelles
• Plant & Animal Cells
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*Cell (plasma) membrane
*Cytoplasm
Nucleus
Nuclear membrane
(envelope)
Nucleolus
*Ribosome
Endoplasmic Reticulum
Golgi Bodies (Apparatus)
Mitochondrion
Cytoskeleton
Vacuole
Lysosome
• Plant Cells
– Chloroplast
– *Cell wall
• Animal Cells
– *Cilia & flagella
– Centrioles
Nucleus
• Control Center for Cell
– Surrounded by nuclear
membrane (envelope)
• selectively permeable
– Inside nucleus
• Chromatin
– DNA & Protein
» Genetic information
– Before cell divides
chromatin condenses
into chromosomes
• Nucleolus
Nucleolus
• In nucleus
– where RNA is
produced
– can have more
than one
Ribosomes & Endoplasmic Reticulum
• Ribosomes
– Synthesize proteins from amino acids
– Thousands in cell
• attached to endoplasmic reticulum
• free in cytoplasm
Ribosomes & Endoplasmic Reticulum
• Endoplasmic Reticulum (ER)
– Network of interconnected,
flattened, tube-like membranes
– transport proteins through cell
• Rough ER (RER)
– covered w/ ribosomes
• Smooth ER (SER)
– Lacks ribosomes
Golgi Bodies (Apparatus)
• Stacks of flattened, slightly-curved, sac-shaped
membranes
– Packages, modifies
& exports proteins
within & out of cell
– Lie close to ER
Mitochondria
• Rod-shaped
– Inner membrane is highly folded
• Why?
• Powerhouse of the cell
– Creates energy (ATP) for cell from
food (glucose)
• Cellular respiration
Cytoskeleton
• Made of microtubules
& microfilaments
– proteins
• Give cell shape &
support
• Helps organelles
move around cell
Vacuole
• Fluid-filled sac
– Plant cells-large vacuole
– Animal cells-small vacuoles
• Store food, water, waste
• Role in maintaining
osmotic balance
– Central vacuole
• Maintains turgor pressure in plants
– Contractile vacuole
• Pumps water out of many unicellular freshwater protists
– Why would these organisms need to pump out water?
Lysosomes
Lysosome animation
• Small, round vesicles formed from golgi bodies
– mostly in animals cells
• contain digestive enzymes
– break down larger food molecules
– break down old, worn out cell parts
Chloroplasts
• Green, oval-shaped plastids w/ double-membrane
– Contains chlorophyll (green pigment)
• Site of photosynthesis
– Makes food (glucose) & releases oxygen
• Plants & some protists
Chloroplast Cyclosis
Cell Wall
• outside cell (plasma) membrane
• protection & support
– made of cellulose or chitin
• plants, algae, fungi, bacteria
Cilia & Flagella
• made from microtubules
– cilia
• Shorter & more numerous
– flagella
• Longer, but few in number
• For motility (movement)
– whip-like motion
Centrioles
• Paired, rod-like structures near nucleus
– made of a cylindrical of microtubule pairs
• Animal cells
• play role in cell division
– separate chromosome pairs during mitosis
Extras
• ID eukaryotic animal cell organelles:
http://www.wisconline.com/Objects/ViewObject.aspx?ID=AP11
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• Cell Part ID interactive: http://www.wisconline.com/objects/ViewObject.aspx?ID=AP114
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• Cell Organelles Game:
http://www.quia.com/mc/65947.html