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Cell Wall, Plasma Membrane, Nucleus - Human Biology |, Study notes of Human Biology

Cell Material Type: Notes; Class: Human Biology; Subject: Biology / Biological Sciences; University: Shippensburg University of Pennsylvania; Term: Forever 1989;

Typology: Study notes

2010/2011

Uploaded on 03/08/2011

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Cell Wall- present in plant, fungi, prokaryotes, and some protists; outer layer that
maintains cell's shape and protects cell from mechanical damage; made of cellulose, other
polysaccharides, and protein; one per cell
Plasma Membrane- present in all cells; membrane enclosing the cell; one per cell
Organelles bounded by a double lipid bilayer:
Nucleus- present only in eukaryotic cells; surrounded by nuclear envelope perforated by
nuclear pores, the nuclear envelope is continuous with the endoplasmic reticulum; houses
chromosomes made of chromatin, contains nucleoli; pores regulate entry and exit of
material, about 5 um in diameter; directs protein synthesis by synthesizing mRNA
according to instructions provided by the DNA; one per cell
Mitochondrion- present in eukaryotes; bounded by double membrane, inner membrane
has foldings (cristae); responsible for cellular respiration; many per cell
Chloroplast- present in plants and algae; typically two membranes around fluid stroma,
which contains membranous thylakoids stacked into grana; responsible for photosynthesis;
many per cell
Organelles bounded by a single lipid bilayer:
The Endoplasmic Reticulum (ER): present in eukaryotic cells; network of membrane-
bound tubules and sacs, separates lumen from cytosol, continuous with the nuclear
envelope
Rough ER- has ribosomes on the outer surface of the membrane and thus appears
rough; functions as making secretory proteins, membrane factory for cell
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  • Cell Wall-^ present in plant, fungi, prokaryotes, and some protists; outer layer that maintains cell's shape and protects cell from mechanical damage; made of cellulose, other polysaccharides, and protein; one per cell
  • Plasma Membrane-^ present in all cells; membrane enclosing the cell; one per cell
  • Organelles bounded by a double lipid bilayer:
    • Nucleus-^ present only in eukaryotic cells; surrounded by nuclear envelope perforated by nuclear pores, the nuclear envelope is continuous with the endoplasmic reticulum; houses chromosomes made of chromatin, contains nucleoli; pores regulate entry and exit of material, about 5 um in diameter; directs protein synthesis by synthesizing mRNA according to instructions provided by the DNA; one per cell
    • Mitochondrion-^ present in eukaryotes; bounded by double membrane, inner membrane has foldings (cristae); responsible for cellular respiration; many per cell
    • Chloroplast-^ present in plants and algae; typically two membranes around fluid stroma, which contains membranous thylakoids stacked into grana; responsible for photosynthesis; many per cell
  • Organelles bounded by a single lipid bilayer:
    • The Endoplasmic Reticulum (ER):^ present in eukaryotic cells; network of membrane- bound tubules and sacs, separates lumen from cytosol, continuous with the nuclear envelope - Rough ER-^ has ribosomes on the outer surface of the membrane and thus appears rough; functions as making secretory proteins, membrane factory for cell
  • Smooth ER-^ outer surface lacks ribosomes; functions in diverse metabolic processes which vary with cell type; processes include synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and proteins
  • Golgi Apparatus-^ center for manufacturing, warehousing, sorting, and shipping, extensive in cells specialized for secretion; modifies and stores products such as proteins and then sent to other destinations; consists of flattened membranous sacs (cisternae), hundreds of stacks per cell; one per cell
  • Lysosomes-^ present in animal cells; membranous sac of hydrolytic enzymes that cells use to digest macromolecules; carries out intracellular digestion, phagocytosis, recycle cell's own organic material (autophagy)
  • Vacuoles-^ membrane-bound vesicles whose function varies in different types of cells; carry out hydrolysis in plant and fungi cells; plant cells enlarge as vacuoles absorb water; can hold reserves of important organic compounds; main repository of inorganic ions; disposal site for metabolic by-products; contain compounds that are poisonous to animals; several per cell
  • Food Vacuole-^ formed by phagocytosis
  • Contractile Vacuole-^ present in freshwater protists; pump excess water out of cell, maintain a suitable concentration of ions and molecules inside the cell; vacuole membrane is selective in transporting solutes
  • Central Vacuole-^ present in mature plant cells; develops by the coalescence of smaller vacuoles, integral part of a plant's endomembrane system
  • Organelles with no membrane component: