lecture_notes_2-7 - Lecture 2 Principles of Cellular...

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Lecture 2: Principles of Cellular Physiology Reading: chapter 2 chapter 3: membrane structure and composition, pgs 52-58 (pgs 56-62 if using 5 th edition) Levels of Organization (Figure 2-1) Plasma membrane Nucleus Cytoplasm Organelles endoplasmic reticulum Golgi complex lysosomes peroxisomes mitochondria vaults Cytosol Cytoskeleton microtubules microfilaments intermediate filaments microtrabecular lattice Plasma membrane: Thin membrane enclosing each cell (Figure 3-1) composed of phospholipid bilayer embedded with proteins and carbohydrates (Figures 3-2, 3-3) separates intracellular and extracellular spaces serves as a barrier to diffusion membrane proteins can selectively transport molecules and ions can act as receptors to signal responses by the cell can form adhesions and junctions with other cells Nucleus: Membrane bound organelle containing the genetic material Deoxyribonucleic acid (DNA): genetic material directs protein synthesis; serves as genetic blueprint during cell replication Ribonucleic acid (RNA): carries out protein synthesis messenger RNA DNA’s genetic code is transferred to mRNA via transcription and the message
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ribosomal RNA participates in reading the message and translating the message into the appropriate protein sequence ( translation) transfer RNA transfers the appropriate amino acid in the cytoplasm to their designated site in the protein being constructed Cytoplasm: portion of cell’s interior not occupied by the nucleus Organelles membrane-enclosed structures that carry out specific functions 6 main types similar in all cells Endoplasmic reticulum (ER) continuous fluid filled network of membranous tubules (Figure 2-2) rough ER ER membrane covered with ribosomes that synthesize and release proteins into the ER lumen. The protein products can be secreted or transported to sites within the cell. ribosome constructed in the nucleus and programmed to carry out the synthesis of a single type of protein smooth ER ER membrane lacking ribosomes that serves to package and transport molecules synthesized in the rough ER. Portions of sER bud off to form transport vesicles that move to the Golgi complex for further processing Golgi complex sets of flattened, membrane-enclosed sacs stacked in layers and specialized for processing raw materials into finished products, and directing the products to their destinations including secretion exocytosis membrane enclosed vesicles containing finished products fuse with the plasma membrane thereby secreting the contents. (Figure 2-3, 2-4, 2-5) Lysosomes membrane-enclosed sacs derived from the Golgi complex containing hydrolytic enzymes to digest and remove unwanted material. These organelles fuse with endocytotic vesicles to breakdown internalized material. endocytosis
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lecture_notes_2-7 - Lecture 2 Principles of Cellular...

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