Anatomy and Physiology Exam 1- FigueroaThe Plasma Membrane•The fluid mosaic model•Membrane lipids •Lipid bilayer forms the fabric of themembrane•Composed of phospholipid molecules•Head = polar and hydrophilic ( philicmeans it likes water/ if water soluble)•Tail = hydrophobic (phobice means it is afraid of water/ insoluble in water). Uncharged, nonpolar. It is made up of two fatty acid chains •Membrane Proteins •Integral proteins: firmly inserted into the lipid bilayer•some only protrude from only one membrane surface•most are transmembrane: span the entire width of the membrane and stick out both sides•most are involved in transport•some clump together to form channels, or pores, through which water-soluble molecules or ions can move through•others are carriers that bind to a substance and then move it through the membrane•receptors•Peripheral proteins: are not embedded in the lipid•they attach loosely to integral proteins•Functions•transport from one side to the other•enzymatic activity•substrate to produce products•Receptors for signal transduction•Neurotransmitters•Hormones•Membrane Transport •Passive process= no energy used •Diffusion: the tendency of molecules or ions to move from high concentration to low concentration along their concentration gradient•passive transport •occurs if:•lipid soluble•small•assisted by carrier molecule•Simple Diffusion: unassisted diffusion •lipid soluble substances and nonpolar•oxygen and carbon dioxide•dependent on the concentration gradient•Facilitated Diffusion: assisted•Limited by the number of protein channels available•Amino acids, ions, and Glucose•travel via:•Carriers: binding to protein carriers in the membrane and ferried across•for bigger molecules•amino acids and glucose•Channels: moves through water-filled protein channels•ions/ electrolytes use channnels•Osmosis: the diffusion of a solvent, such as water, through a selectively permeable membrane•Solutes attract water•Occurs when the concentration of a solvent is different on opposite sides of a membrane•Osmolarity: total concentration of a solute in a solution•Tonicity•Isotonic: solutions with the same solute concentration as the cytosol•nothing happens•Hypertonic: solution has a higher solute concentration than the cytosol•loses water-> shrivels up•Hypotonic: solution has a lower solute concentration•gains water -> cell expands. if RBC ruptures= hemolysis•Active Process •Active Transport•Carrier-mediated facilitated diffusion•Requires carrier protein that combine specifically and reversibly with the transported substance•Solute pumps move solutes, most ions, against their concentration gradient•ATP is needed•Primary Active transport•requires carrier proteins •Antiports: transport mechanism that moves two substances in opposite directions•ATP is energy.•ATPase breaks ATP into ADP as well as transports it•Ex. Sodium- Potassium Pump•Carrier is called: sodium-potassium ATPase•K+ inside the cell is 10x higher in concentration than outside of the cell•Na+ is higher in concentration outside•never have more Na+ inside•3 Na+ leaves (goes out of the cell) and 2 K+ move into the cell•the result the Na+/K+ pump ( the Na+) provides energy for the Secondary Active transport•Secondary Active transport•transport driven indirectly by energy stored in ionic gradients created by the primary active transport pumps•Symports: transport mechanism that moves the substance in the same direction•Glucose and Amino Acids need Na+ to enter•Glucose has a different transporter that AAs but move in the same direction•If Na+ goes from high->low ALONE: it is using facilitated diffusion•If Na+ goes from low -> high in a TRANSPORTER w/ ATP: it is using Primary Active transport•if Na+ goes from high -> low w/ AA or Glucose: it is using Secondary Activetransport←•Vesicular Transport•transport of large particle and macromolecules across the plasma membrane•Ex. Receptor- mediated Endocytosis•Phospholipid bilayer is main component of plasma membrane •Exocytosis: movences from the cell’s interior to the extracellular space•Endocytosis: move substances from the outside of the cell to the inside•Phagocytosis: cell’s “eat” large particles•think of the particle as a large burger...you need to take bites to eat it•Pinocytosis: the cell “drinks” the small particles•think of the particle as a pill... you don’t need to break it down, you just swallow it•Vesicles fuse to the lysosome←•Cytoplasm: consists of everything between the nucleus and the cell membrane•Cytosol: the intracellular fluid•mostly water but also contains dissolved chemicals•between the plasma membrane and the nuclear membrane (both have a lipid bilayer)• Organelles: structures that each perform specific functions for the cell•Ribosomes: the site of Protein Synthesis•two major subunits made up of RNA and proteins•mRNA is in the space between the two subunits•Free ribosomes make proteins used in the cytosol•Attached ribosomes make proteins used in membranes and for export•Endoplasmic Reticulum•an extensive membrane network within the cytosol•Rough ER: contains bound ribosomes•Smooth ER: has enzymes involved in metabolism of lipids and drugs...NO ribosomes attached•no contact between the Rough ER and the Golgi, just as there is no contact between the Golgi and the cell membrane←•Golgi Complex•modifies and sorts out proteins produced by the rough ER•generates vesicles for moving molecules•Protein goes from rough ER -> Golgi -> plasma membrane•Protein travels in a vesicle•Vesicle fuses with the plasma membrane and allows protein to exit the cell (exocytosis)•rough ER forms the membrane of the vesicle•to complete protein synthesis, it MUST go through the golgi•Transcription: the process where a DNA sequence is copied into RNA sequence•occurs in the nucleus•transfers genetic info from DNA into one of 3 major classes of RNA•messenger RNA (mRNA)•ribosomal RNA (rRNA)•transfer RNA (tRNA)•the enzyme RNA polymerase creates the RNA molecules•enzyme breaks down bonds and begins reading amino acids•RNA uses U (uracil) rather than T (thymine)•if the RNA sequence is meant to encode proteins it is called messenger RNA (mRNA)•the mRNA sequence is used to make new proteins
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