PET3322 Exam 1 Study Guide CHAPTER 3 Cellular Level of Organization Three Parts of Cells Plasma Membrane plasma membrane flexible outer surface cytoplasm contains organelles surrounded by cytosol nucleus large organelle that contains cell s chromosomes 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 Epithelium Primary functions protection ex skin absorption ex intestines 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 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 cell to large clusters of cells two categories of glands endocrine secrete hormones and exocrine secrete materials into ducts or directly onto an apical surface endocrine glands secretory products hormones diffuse
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