Chapter 3- Cellular Level of Organization Plasma Membrane F(x): 1. Physical Isolation conditions inside & outside the cell constant to preserve homeostasis 2. Regulation of Exchange with the Environment controls the entry of ions & nutrients, the elimination of wastes, & the release of secretions 3. Sensitivity to the Environment contains variety of receptors that allow the cell to recognize & respond to specific molecules in its environment 4. Structural Support specialized connections b/w plasma membrane or b/w membrane & extracellular materials Phospholipid Bilayer Regulate movement of molecules in/out, semi-permeable Hydrophilic phosphate heads & Hydrophobic lipid tails Cholesterol: large steroid/lipid -helps maintain structure Membrane Proteins: Anchoring- attach plasma membrane to other structures & stabilize its position Recognition- allows immune system cells to recognize self vs nonself Enzymes- catalyze reactions in cytosol or extracellular fluid Receptors- sensitive to extracellular molecules > ligands Carrier- binds solutes & transport them across membrane (some require ATP) Channels- movement of H2O & small solutes Membrane Carbs: Proteoglycans Glycoproteins Glycolipids Make up layer called Glycocalyx F(x): lubrication & protection Anchoring & locomotion Specificity in binding-alters property of cells surface Recognition- self vs nonself Organelles Outline sheet Section 3-2 : Read pages 68-77 Organelles Cytoplasm- contains cytosol & organelles Nucleus- control of metabolism, storage & processing of genetic information, control of protein synthesis Rough ER- modifies & packages newly synthesized proteins Ribosomes- protein synthesis Smooth ER- synthesizes lipids & carbohydrates Golgi body with vesicles- modifies & packages secretions for release through exocytosis, renews or modifies the plasma membrane, packages special enzymes within vesicles for use in the cytoplasm Lysosome- intracellular removal of damaged organelles or pathogens Peroxisome- catabolism of fats & other organic compounds, neutralization of toxic compounds generated in the process Proteasomes- breakdown & recycling of damaged or abnormal intracellular proteins Mitochondria- produces 95% of ATP required by the cell Centrioles- found during cell division, form spindle apparatus Cilia- move fluids/secretions across the cell surface Cytoskeleton- metabolic organization, internal protein framework, gives cytoplasm strength & flexibility Microfilaments- anchor cytoskeleton to integral proteins of plasma membrane, determines consistency of cytoplasm, movement of cell Intermediate filaments- strengthen cell & help maintain its shape, stabilize the positions of organelles, stabilize position of cell to surrounding cells Microtubules- cell strength & rigidity, position of organelles, assist in movement, spindle apparatus, structural components Thick filaments- composed of myosin, interact with actin filaments to produce powerful contractions Nucleus Controls metabolism, storage, & processing of genetic info, control of protein synthesis Contains DNA & enzymes to control cellular activities Genetic code: DNA set of instructions 3 letter word = codon > specific amino acid chains DNA > RNA > proteins The Inner Life of the Cell Diffusion- passive transport Movement of molecules from areas of high concentration to low Down concentration gradient Through phospholipids/ channel proteins Osmosis- diffusion of water Isotonic- equal Hypotonic- salt outside is less = cell bursts (lysis) Hypertonic- more salt outside = water leaves = crenation (shrinking) Carrier Mediated Transport (passive/active) Transportation of ions & organic substrates Characteristics: Specificity: only bind to certain things Saturation: limits to rate Regulation: hormones 1. Facilitated Transport- passive Large polar molecules & ions move across membrane 2. Active- requires E Ion pumps- exchange pumps ex: Na/K Passive vs. Active Transport Vesicular Transport- ATP required 1. Endocytosis- take in using vesicles Receptor mediated target molecules Pinocytosis-liquid Phagocytosis- solids 2. Exocytosis- secretion, hormones/vesicles Facilitated Diffusion vs Active Transport Similarities: Carrier proteins Transport large molecules/ions Differences: FD- w concentration gradient AT- against conc. Gradient AT- requires E, FD doesnt Transmembrane Potential Charges are separated creating a potential difference Unequal charge across plasma membrane is transmembrane potential Resting potential= -10mV to -100mV, depending on cell Minus sign signifies inside of plasma membrane contains an excess of charges compared with outside Creates potential E Cell Cycle Interphase- cell increases in mass, doubles its cytoplasm & duplicates its DNA G1- cytoplasm doubles S- DNA is copied G2- proteins/enzymes required for cell division are made Mitosis Prophase- chromosomes condense Metaphase- chromosomes line up in middle Anaphase- separation Telophase- condense Cytokinesis- division into 2 daughter cells Late anaphase > telophase Marks end of cell division Cell Cycle and Mitosis Regulation of Cell cycle Proteins & enzymes are responsible 1. Cyclins- family of proteins that increase and decrease in number during cell cycle, bind to kinases to activate them M cyclins- during mitosis S cyclins- during interphase 2. Kinases- Cdk (cyclin dependent kinases)-family of enzymes that drive the cell cycle, active only when bound to cyclin When damage is found, the checkpoint uses a signal mechanism either to stall the cell cycle until repairs are made or, if repairs cannot be made, to target the cell for destruction via apoptosis Cancer Uncontrolled cell division- tumor growth Proto-oncogenes- naturally occurring, normally promote cell division when on Oncogene- mutated form, permanently spin cell cycle Tumor Suppressor Genes- naturally occurring, stop cell cycle Formation of Cancer Starts with a mutation Genetic, virus, environment (smoking, radiation, UV) Cell becomes non-functional, not density dependent, and does not stick together = primary tumor Angiogenesis- formation of blood supply Benign-doesnt spread Malignant- will spread Uses blood or lymphatic system to spread = Metastasis =secondary tumor Cancer Video Cell Differentiation Development of specific cellular features All cells throughout the body contain the same set of chromosomes & genes, but a different set of genes has been turned off All have 46 chromosomes Liver cells dont have genes for production of insulin turned on Stem cells- undifferentiated and can become many cell types