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24 Cards in this Set

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Cell Structure
- what are cells?
- name the major classes
* Cells are the structural/functional units of all living organisms
* 3 major classes of biological units:
- viruses/prokaryotes/eukaryotes
Cell
- general
* surrounded by a membrane
* divided into compartments which are enclosed with membranes
* compartments are called ORGANELLES

2 REGIONS OF CELL:
- NUCLEUS contains chromosomes
- CYTOPLASM contains organelles and cytosol
Membranes
- general
* SURROUND cell (separate cell from environment
* ENCLOSE organelles (confine chemical reactions within organelle)
* REGULATE PASSAGE of materials IN/OUT of cell
* ANCHOR cells to adjacent cells
* contain RECEPTORS for detection of chemical signals
* attachment site for protein filaments (in smooth muscle cells)
* all membranes are a DOUBLE LAYER OF PHOSPHOLIPID in which protein is embedded
Phospholipid
* restricts movement of most molecules
* amphipathic

hydrophilic portion
hydrophobic portion
Hydrophilic portion of phospholipid membrane
* polar/ionized part of molecule
* oriented toward membrane surfaces
* attracted to polar water molecules in extracellular fluid and cytosol
Hydrophobic portion of phospholipid membrane
* nonpolar/unionized part of molecule
* oriented with fatty acid chains in middle of double layer
Membranes:

Protein
* serves as pores or channels in membrane
* 2 kinds of membrane proteins:
- integral proteins
- peripheral proteins
* small amount of carbohydrate covalently linked to lipid or protein (monosaccharides/extracellular surface)
* fluid-mosaic model
Membranes:

Protein -
Integral proteins
* amphipathic (polar amino acid/nonpolar side chains)
* oriented like phospholipids (polar-surface/nonpolar-inner)
* transmembrane
* some form channels for water/ions
* some transmit chemical signals across
Membranes:

Protein -
Peripheral proteins
* not amphipathic
* on surface bound to polar region of integral protein
* most on cytosol surface
* associated with cell shape and motility
Plasma membranes of cells intract to form ...
tissues
Name the types of
CELL JUNCTIONS
3 types:
Desmosomes
Tight junctions
Gap junctions
Cell Junctions:

Desmosomes
* thick glycoprotein at each surface
* fibers extend into cell/across
* firm hold from cell to cell
* occur where stretch occurs
* disc shaped
ie: skin, lining of body cavities
Cell Junctions:

Tight junctions
* no extracellular space... membranes join
* form band around cell
* restrict molecules
ie: epithelial lining of stomach, intestine and nephrons
Cell Junctions:

Gap junctions
* between most cells
* protein channels join cells across gap
* small diameter
* small molecules/ions pass
* proteins held back
* transmit electrical signals and chemical messengers
ie: cardiac/smooth muscle
Organelles:

Nucleus
* surrounded by nuclear envelope (membrane) / pores
* contains chromosomes (DNA/genetic information)
* contains nucleolus (DNA, RNA, protein)
* site where ribosomes assembled ... go to cytoplasm
Organelles:

Endoplasmic Reticulum (ER)
* membrane system
* network connects nuclear/plasma membrane
granular ER - ribosomes ... protein synthesis
agranular ER - no ribosomes ... lipid synthesis
(and in the case of muscle cells - Ca++ storage)
Organelles:

Ribosomes
* composed of protein/RNA
* synthesize protein
on ER ... Golgi ... protein for export
free/chains or clusters ... protein for cell (aka polysomes)
Organelles:

Golgi Apparatus
* membranous sacs
* near nucleus
* packages protein synthesized into vesicles
Organelles:

Mitochondria
* rod-like structure
* energy for cell
* site of ATP formation
* number varies (few/1,000)
Organelles:

Lysosomes
* spherical organelle
* several hundred/cell
* sacs of hydrolytic enzymes break down bacteria, debris from dead cells that have been engulfed by cell
(phagocytes)
Organelles:

Peroxisomes
* oval sacs
* contain OXIDATIVE ENZYMES which use o2 to remove H in order to detoxify molecules and form H2O2
* also contains CATALASE which catalyzes the conversion of H2O2 to H2O and O2
Organelles:

Microfilaments
* contractile proteins
* cytoskeleton/ mechanical stress
Organelles:

Microtubules
* hollow tubes
* cytoskeleton, centrosomes, centrioles
Organelles:

Cilia
* hairlike on epithelial cells
* produce movement