Cellular Form Cytoplasm material betwee the plasma membrane and the nucleus incl fibers organelles etc Cytosol intracellular fluid clear gel Plasma membrane defines the boundaries of the cell governs its interactions with other cells controls the passage of materials into and out of cell Lipids 98 Phospholipids 75 amphiphilic Keep membrane fluid Cholesterol 20 stiffen membrane in spots Glycolipids 5 phospholipids with short carbohydrate chains on the extracellular surface Form a carbohydrate coating on the cell surface Proteins 2 much larger Types Functions Integral transmembrane proteins Can be drifting or anchored on the cytoskeleton Peripheral adhere to one face of the membrane Typically anchored Receptors chemical signals bind to it Usually specific Second messenger messenger on surface produce second messenger in cytoplasm Enzymes final stages of starch protein digestion Break down hormones etc Channel proteins open or gated Ligand voltage or mechanically gated Carriers bind and transfer glucose etc Example pumps Cell identity markers enables the body to tell which cells belong to it vs foreign Cell adhesion molecules mechanical link Microvilli extensions of the plasma membrane increase surface area sensory role Some have stiff filaments actin anchored to terminal web Cilia hairlike processes Nearly every cell has one non motile sensory Motile less widespread propel mucus egg cells etc Has microtubules 9 2 structure Flagellum whiplike tail of the sperm Cytoskeleton Microfilaments protein actin Form terminal web support phospholipids and microvilli Intermediate filaments various proteins keratin etc Thicker and stiffer Shape cell resist Play a role in cell movement stress participate in junctions Microtubule tubulin globular protein Radiate from centrosome Hold organelles in place maintain cell shape and rigidity Proteins walkways Form cilia and flagella Organelles internal structures of the cell Carry out specialized metabolic tasks Nucleus genetic control center of the cell Two membranes form nuclear envelope perforated with nuclear pores proteins that regulate molecular traffic Outer membrane is continuous with rough ER Nucleoplasm Chromatin DNA and protein Density varies depending on what the cell is doing at the time Nucleolus produce ribosomes NOT a separate structure Endoplasmic Reticulum network of cisternae interconnected channels Rough ER parallel flattened cisternae covered with ribosomes Produces phospholipids and proteins for secretion most abundant in antibody producing and digestive cells Smooth ER tubular branched cisternae Detoxify abundant in liver and kidney cells Metabolize lipids glycogen Stores Ca Ribosomes small granules of protein and RNA Found in the nucleoli mitochondria cytosol surface of rough ER nuclear envelope Assemble proteins and amino acids specified by RNA code Golgi Complex small system of cisternae about 6 Synthesize carbohydrates Finish protein and glycoprotein synthesis received from rough ER some become lysosomes or fuse with plasma membrane Lysosomes package of hydrolitic enzymes in a single unit membrane Produced by Golgi complex Digest foreing substances phagosome recycle surplus of nonvital organesses autophagy Also apoptosis programmed cell death autolysis Peroxisomes different enzymes Produced by ER Oxidize organic molecules Neutralize free radicals detoxify alcohol etc decompose fatty acids into energy source for ATP synthesis Proteasomes Mitochondria double unit membrane Inner membrane folded into cristae Specialized for synthesizing ATP Centrioles short cylindrical assembly of microtubules Play a role in cell division mitotic spindle Membrane Transport Passive require no ATP Filtration diffusion osmosis Active consume ATP Active transport vesicular transport Passive Filtration physical pressure forces fluid through a selectively permeable membrane blood pressure Simple diffusion net movement of particles from high concentration to lower Down the gradient Diffusion rates can be affected by temperature molecular weight steepness of the concentration gradient membrane surface area and permeability Diffusion through the phospholipid bilayer non polar permeable to non polar non permeable to polar Slightly permeable to water and urea Osmosis net flow of water through selectively permeable membrane From the side of high concentration of water molecules less dissolved matter to lower water concentration Aquaporins channel proteins specialized for the passage of water Hydrostatic pressure water weight Osmotic pressure Tonicity hypotonic solution cells swell and burst Hypertonic cell crenation Isotonic Passive but requires a carrier Facilitated diffusion carrier mediated transport of a solute through a membrane down its concentration gradient membrane ion channels open K and Cl most common or voltage or ligand gated all are ion specific Specificity saturation properties Types of carriers Uniport carry only one type of solute Symport 2 in the same direction cotransport sodium glucose Antiport 2 in opposite direction countertransport Na K or Na Ca Active Primary active transport moves a substance through a cell membrane up its concentration gradient using ATP Na K Secondary active transport depend on ATP indirectly sodium glucose transporter depends on Na K pump to maintain low Na concentration Vesicular transport Endocytosis bring matter into the cell Phagocytosis cell eating engulfing particles such as bacteria dust and cellular debris Pinocytosis cell drinking Taking in droplets of ECF All human cells Receptor mediated endocytosis taking in ECF particles too big for channels Bind to receptor on membrane pit coated with clathrin is created clathrin coated vesicle Exocytosis discharging material from a cell Endocytosis in reverse Replace plasma membrane DNA Function carry instructions genes for synthesis of proteins Polymer of nucleotides 3 nucleotides of DNA base triplet codon of mRNA Nucleotide sugar phosphate group nitrogenous base 1 ring pyrimidine C T 2 rings purine A G Law of complementary base pairing A T 2 hydrogen bonds C G 3 hydrogen bonds base pairs Chromatin filamentous material chromosomes 46 filaments DNA winds around histones 8 protein discs forms nucleosomes then zigzags then forms irregular loops and coils When preparing to divide makes a copy sister chromatids joined by centromere pinched spot in the middle Kinetochores protein plaques on each side of centromere RNA smaller single chain ribose uracil instead of thymine