PET3322 Exam 1 Study GuideCHAPTER 3 – Cellular Level of Organization~Three Parts of Cells*plasma membrane (flexible outer surface), *cytoplasm (contains organelles surrounded by cytosol), *nucleus (large organelle that contains cell’s chromosomes)~Plasma Membrane*strong but flexible barrier betw/ cell interior and the outside world*membrane structure described fluid mosaic model- Phospholipid bilayer provides structural foundation-a variety of membrane proteins interact with the lipids-all lipids and many proteins are able to move about freely*membrane used as means for cells to communicate with other cells and with environment~Lipid Bilayer *Phospholipid bilayer is effective barrier for polar and charged molecules, ions~Sub-classes of membrane proteins exist:*integral proteins, peripheral proteins, glycoproteins~Membrane Permeability*small/non-polar molecules pass easily*permeability to ions/polar molecules depends on number of specific transport proteins*how quickly ions and molecules cross membrane depends on: conc gradient of ion/molecule, electrical gradients that speed/slow movement ~Active vs Passive Processes*Passive processes are spontaneous:-chemicals move based on kinetic energy-movement is from high to low conc. (downhill)-ex: simple diffusion, facilitated diffusion, osmosis*Active processes use stored energy:-energy input required for chemicals to move-movement is from lower to higher conc. (uphill)-ex: primary/secondary active trans., endocytosis~Diffusion – Passive Movement of Solutes*movement of solutes directly through bilayer is simple diffusion*movement of solutes with the help of membrane proteins is facilitated diffusion*rate of diffusion depends on:-concentration gradient-temperature-mass of diffusion ion/molecule-membrane surface area-diffusion distance*non-polar molecules: simple diffusion*ions: use ion channels, facilitated diffusion*polar molecules: carrier-mediated facilitated diffusion~Passive Membrane Transport*does not require ATP*net diffusion stops when conc on both sides equal or when there is a uniform dist of particles-equilibrium is reached-molecules continue to move, but no net change in conc (net diffusion)*simple diffusion: along/down conc gradient, non-polar and lipid-soluble substances (O2, CO2)-diffuse directly through lipid bilayer*osmosis – water always moves toward higher solute level-cell in hypotonic solution: gains water, ruptures (hemolysis of RBCs)-cell in hypertonic sol’n: loses water, shrinks/shrivels-cell in isotonic sol’n: equal conc inside and outside~Active Transport*chemicals move “uphill” (against conc gradient)*energy required*Three types of active processes:-primary active trans: ATP is source of energy-secondary active trans: ions gradients are source of energy-transport in vesicles: some large molecules can enter (endocytosis) and leave (exocytosis) cells without being broken down*Primary Active Transport-pumps ions “uphill” (against conc gradients)-powered by ATP hydrolysis-solutes transported across plasma membrane from low conc to high conc-inside of cells becomes more (-), loses 3 Na+ and gains only 2 K+-ex: Na+/K+ pump, antiports (movement in opposite directions)*Secondary Active Transport-moves glucose and amino acids (also against conc gradient)-energy comes from Na+ gradient-symports (movement in same direction) *Transport in Vesicles-vesicles are small spherical membrane sacs-used to move large molecules in and out of cells, and betw/ organelles-ex: receptor-mediated endocytosis-endocytosis: molecules taken in by the cell; phagocytosis (cell “eats” large particles); pinocytosis (cell “drinks” in smaller particles than in phago.)- exocytosis: vesicular transport of big solutes out of cell; material for secretion ex: hormones, neurotransmitters, enzymes~Cytoplasm consists of everything betw/ the nucleus and the membrane*cytosol is the intracellular fluid, mostly water but with many dissolved chemicals*organelles are structures that each perform specific functions~Ribosomes: Site of Protein Sythesis*have two major subunits; small subunit and large subunit combine to create functional ribosome*made of both RNA and proteins*free ribosomes make proteins used in cytosol*attached ribosomes make proteins used in membranes for export~Endoplasmic Reticulum*extensive membrane network within the cytosol*rough ER contains bound ribosomes*smooth ER has enzymes involved in metabolism of lipids and drugs~Proteins are an expression of genetic info*transcription is the process where DNA sequence is copied (transcribed) into RNA sequence- transcription transfers genetic info form DNA into one of 3 types of RNA: messengerRNA, ribosomalRNA, or transferRNA- if the RNA contains sequence meant to encode proteins, it is mRNA- enzyme RNA polymerase creates RNA molecules-regulation of transcription is a way for cells to control which proteins are made*mRNA sequence is used to make new proteins in process of translation*translation: using mRNA and ribosomes to create proteins- ribosome subunits combine when mRNA is available-ribosomes are made of proteins and rRNA, and have multiple binding sites for mRNA and tRNA- tRNA helps line up correct animo acids to make new protein- a leader sequence on mRNA attaches to small subunit of ribosome, ribosomes begin to read mRNA sequence- to convert mRNA into protein, tRNA is used to read the mRNA sequence, 3 nucleotides at a time (codons)CHAPTER 4 – Tissue Level of Organization~Tissues are classified in 4 types*epithelial – cover external/internal surfaces of body, also form secretory glands*connective – protect and support other tissues, various organs*muscle – create forces that allow movement; generate body heat*nervous – collect and analyze info about body; signal muscles and glands to take action~Epithelium*Primary functions:-protection; ex: skin- absorption; ex:intestines-filtration; kidneys- excretion/secretion; saliva, sweat*all epithelia are directional; they have an apical (outer) surface and basal and lateral surfaces-basal surface rests upon a basement membrane made of extracellular material*surface epithelia are describes by two structural characteristics: arrangement of cells in layers; cell shape*endothelium: epithelium of blood vessels; endocardium: epith. of heart*glandular epithelia- a gland is one or more cells that makes and secretes and aqueous fluid-glands secrete a variety of chemicals, usually not directly on surface- vary from single
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