How small are cells? How much is a micrometer? 1 micrometer (m)
= 1/1,000,000 m Typical cell size = 5 to 50 m in diameter In a dice
that is 1 cm 3 We could fit 1,000,000 cells
Cytoplasm: Contains the various organelles Area between the
cell membrane and nucleus Jelly-like material
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Nucleus: Stores hereditary information (DNA) Prokaryotic cells
lack a nucleus, but they do contain DNA Control center of the
cell
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Chromatin and Chromosomes: Inside the nucleus are fine strands
of chromatin (a complex of DNA bound to protein) that coil up and
become densely packed, forming chromosomes Chromosomes are visible
under a microscope when a cell divides
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Nucleolus and Nuclear Envelope: Nucleolus small dense region
within the nucleus where ribosomes are synthesized Nuclear Envelope
double membrane (lipid bilayer) that surrounds the nucleus
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Vacuole: Fluid-filled organelles that store water, salts,
proteins, and carbohydrates In many plant cells, there is a single
large central vacuole filled with fluid - can occupy up to 90% of
the cells volume Animal Plant
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Parameciums Contractile Vacuole Contracts rhythmically to pump
excess water out of the cell controls the water content of the
organism
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Lysosomes: Filled with enzymes Breaks down carbohydrates,
lipids, and protein that can be used by the rest of the cell Breaks
down organelles that have outlived their usefulness Removes junk
that would clutter the cell Known as the Clean Up Crew or Suicide
Sac of the cell Found in animal cells and specialized plant cells
Some humans have diseases that result from lysosomes that fail to
function properly.
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Cytoskeleton: Gives cells structure; helps to maintain shape
& size; involved in cell movement Helps to transport materials
between different parts of the cell Network of protein strands
(scaffold) Made up of microfilaments and microtubules
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Microfilaments: Thin threads made of actin (structural protein)
Supports the cell Contribute to cell movement
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Microtubules: Larger strands; hollow tubes made of tubulin
(proteins) Maintain cell shape Important in cell division forms the
mitotic spindle which helps to separate chromosomes Form centrioles
in animal cells Help build cilia and flagella
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Centrioles: Found near the nucleus Used to organize cell
division (mitosis) Made of microtubules arranged in 9 groups of 3
Found only in animal cells 1 2 3 4 5 6 7 8 9
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Cilia: Short hairs present in large numbers Propel unicellular
organisms Line cells of respiratory tract
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Flagella: Longer hairs that are less numerous Found on sperm
cells Whip back and forth
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Ribosomes: Produce PROTEINS by following coded instructions
that come from DNA Most numerous organelle found throughout the
cytoplasm in all cells Not surrounded by a membrane Made of RNA and
protein in the nucleolus & transported to the cytoplasm
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Endoplasmic Reticulum (ER): Moves molecules from one part of
the cell to another Intracellular Highway System of membranous
tubules & sacs
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Rough ER: Dotted with ribosomes Involved in the synthesis of
proteins Abundant in cells that make large amounts of protein
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Smooth ER: Does not have ribosomes attached Contains
collections of enzymes that perform specialized tasks (i.e.
detoxifying - liver)
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Golgi Apparatus: Modifies, sorts and packages proteins and
other materials for storage or release Processing, packaging, and
secreting organelle Works with the ER Modifies proteins for
export
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Mitochondria: Convert chemical energy stored in food into
compounds that the cell can use - powerhouse Transfer energy to ATP
(main energy currency) Surrounded by two membranes and contain DNA
Most numerous in cells with high energy requirements (liver &
muscle)
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Chloroplast: Capture solar energy & convert it to chemical
energy Surrounded by two membranes and contain DNA Contains the
green pigment chlorophyll Found only in plant cells
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Cell Wall: Supports and protects the cell Rigid structure
outside the cell membrane Made of cellulose Found only in plant
cells
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Cell Membrane: Controls what materials pass into and out of the
cell Selectively permeable Made primarily of lipids and
proteins
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Fluid Mosaic Model:
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Components of Cell Membrane: 1. Phospholipids polar head &
nonpolar tails 2. Integral Proteins imbedded in lipid bilayer;
usually have carbohydrates attached to them 3. Peripheral Proteins
surface only
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Animal Cell:
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Plant Cell:
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Animal Cell - Label
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Plant Cell - Label
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Great websites to check out! Interactive Cell Models Cells
Alive http://www.cellsalive.com/index.htm Inside a Cell
Learn.Genetics (University of Utah)
http://learn.genetics.utah.edu/content/begin/cells/insideacell/
Video BBC Secret Universe: The Hidden Life of the Cell
http://www.youtube.com/watch?v=4GZXRMG5i_w Video Inside the Cell
http://www.youtube.com/watch?v=Ao9cVhwPg84