The Cell

The stuff that has been boring you for years!

(Brought to you by the people who make learning mandatory so that we can keep our jobs and have summer off!)

The Basics: Prokaryote vs. Eukaryote  Pro: bacteria, archaebacteria, no true nucleus, lacks nuclear envelope, Genetic Material in nucleoid region, no membrane bound organelles, 0.1-10 µm  Euk: Protista, Fungi, Plantae, Animalia, true nucleus, bounded by nuclear envelope, genetic material within nucleus, contains cytosol and membrane bound organelles, 10-100.0µm

Membrane Structure

 Plasma membrane is boundary between living and nonliving, 8nm thick, controls chemical traffic, selectively permeable  Made of amphipathic phospholipids, means hydrophilic and hyrdrophobic region present

Fluid Mosaic Membrane

 Membrane held together by weak hydrophobic interactions  lipids and proteins drift w/in membrane  must be fluid to work properly, moderated by cholesterol

 membrane less fluid at warmer T by restraining movement of phospholipids  at low T, prevent packing of phospholipids  Membrane is a mosaic of diff proteins embedded an dispersed in a phospholipid bilayer

 Integral proteins: transmembrane,  peripheral proteins: attached to membrane surface  Protein functions: channels, transport, recognition, adhesion, receptor, electron transport  Distinct directional orientation  Carbohydrates on exterior, proteins also have directional orientation

 Cholesterol: provide rigidity in animal cells, sterols in plants  Glycolayx: carbohydrate coat covering outer plasma membrane, markers for cell to cell recognition

Organelles & Cell Structures

 Know the following structures and organelles….

 Nucleus, nuclear envelope, ribosome, Endoplasmic reticulum, golgi apparatus, lysosome, peroxisome, mitochondria, chloroplast, cell walls, vacuoles, vessicles,

Cytoskeleton

 Structural support for motility and regulation  Allows cell to change shape  mechanically transmits signals from surface to interior  constructed from three types of fibers  microtubules (thick)  microfilaments(thin)

 Intermediate fibers

Microtubules

 Found in Eukaryotic Cells, hollow, straight, constructed of globular protein called tubulin, reinforce cell shape  Tracks for organelle movement by motor molecules

 Separate chromosomes during cell division  Centrosomes, centrioles, cilia, flagella

Centrosomes and Centrioles

 Centriole: pair of cylindrical structures located in centrososme, composes of nine sets of triplet microtubules arranged in a ring, replicate during division

Cilia and Flagella

 May propel, or draw fluid across membrane  extension of plasma membrane with core of microtubules, 9 + 2 pattern, identical to centrioles, anchored by basal body  Use ATP to power dynein movement

Microfilaments

 Solid rods of globular protein (actin) wound into helix  Provide cellular support, bear tension, aide in muscle contraction (myosin), cytoplasmic streaming, and localized contraction for the cleavage furrow during cell division

Intermediate filaments

 Composed of Keratin, more permanent the microtubules and microfilaments  Bear tension, framework for cytoskeleton, fix organelle position (nucleus)

Cell Junctions

  Desmosomes: protein attachments between animal cells, like a spot weld  Anchor cells to one another, provide passageway for exchange of nutrients and wastes Tight Junctions: stitched seams in animal cells, no movement between, digestive system

Cell Junctions Continued

 Gap Junctions: narrow tunnels, animal cells, consist of proteins called connexons, prevent cytoplasm from mixing, but allow ions to pass  Plasmodesmata: plant cells, desmotubule (from ER) surrounded by cytoplasm passes through

Movement of Materials….Bio Again……  You need to know……   Selectively permeable membrane, osmosis, diffusion, facilitated diffusion, active transport, Endo and Exocytosis (including pinocytosis and phagocytosis), protein pumps New stuff I will teach you……  Dialysis: diffusion of solutes across a selectively permeable membrane, passive transport

Movement of Materials continued  Plasmolysis: the movement of water out of the a cell that results in the collapse of the cell, passive  Countercurrent exchange: diffusion between two regions, like gills and fish blood stream, heat in ducks in legs and body, passive  Receptor-mediated endocytosis: active, specific molecules bind to specialized receptors, form ligands in the pit. Proteins that transport cholesterol and hormones

Veggin’ Out: Photosynthesis

 Photosynthesis: transforms solar light energy trapped by chloroplasts into chemical bond energy stored in sugar and other organic molecules, exergonic redox reaction  Autotrophic nutrition: making organic molecules from inorganic raw materials, called producers,   Photoautotrophs: Use light as E source Chemoautotrophs: use the oxidation of inorganics (S or Ammonia) as source, bacteria

Choloroplast

 Where light dependent and independent take place  Chlorophyll: green pigment, color and absorption, in mesophyll, in thylakoid membranes  Stroma: fluid outside thylakoid

Noncylic Photophosphorylation

  Photophosphorylation: process of making ATP using E from light (the light dependant reaction) Check the diagram and try to remember….

Calvin- Benson Cycle

 Uses ATP and NADPH to reduce CO 2 sugar to  Light Independent

The Production of ATP

 Chemiosmotic Theory: mechanism by which ADP is phosphorylated to ATP  Specifically: coupling of exergonic electron flow down electron transport chain to endergonic AP production by the creation of a proton gradient across a membrane. Proton gradient drives ATP synthesis as protons diffuse back across membrane.

Chemiosmotic Theory

  H+ protons accumulate inside thylakoids ETC in a membrane translocate protons across the membrane as electrons pass through a series of carriers that are progressively more electronegative  ATP Synthases generate ATP

C

4

Photosynthesis

 Higher rate than C 3 , less water loss, for plants in hot, dry climates. Sugarcane and crab grass  Instead of PGA, form OAA (oxaloacetate), a 4 carbon atom, converted to malate, then to pyruvate

CAM Photosynthesis

 Crassulacean acid metabolism (CAM), similar to C4  Happens during day when stomata closed, low water loss, succulents like cacti  OAA to malic acid, back to OAA, then finishes Calvin cycle

The ultimate movement of materials: Cellular Respiration  Extracting stored E from glucose to form ATP, called aerobic respiration  Glycolysis, Krebs cycle, and oxidative phosphorylation   Production of 36 ATP from one glucose Anaerobic respiration: without oxygen, Alcoholic fermentation, lactic acid fermentation

Cell-Cell Recognition

 Basis for:  sorting of embryo’s cells into tissues and organs  rejection of foreign cells by immune system  Recognize by carbs  branched oligosaccharides bonded covalently to lipids and proteins

Cell Communication

 Communicating cells may be close or far apart, communicate by local regulators or hormones  Three stages of cell signaling :  Reception  Transduction  Response

Signal Reception

 Chemical signals bind to specific receptors (receptor protein)  Signal molecules complement to specific region or receptor protein  signal behaves as ligand (small molecule to large molecule)  Signal receptors are plasma mem. proteins

Signal Transduction Pathways

 Pathways relay signals from receptors to cellular responses  Chain of reactions  Information is passed along, passes along info not molecule  second messengers; Cyclic AMP, Ca ions

Cellular Responses to Signals

 In response to signal, cell may regulate activity in cyto or transcription in nucleus  Pathways amplify and specify responses  cAMP: few to many  target cells with receptor bind to specific signaling molecule

Regulation of Cell Cycle

 Controlled by a clock  Internal and external cues regulate  Chemical-nutrients, growth factors  Physical-density-dependent inhibition

 Cancer cells have escaped from cycle controls

Cancer

 Do not stop due to density inhibition  Make growth factors themselves, is abnormal signal  Divide indefinitely as long as nutrients are available, normal 20-50 times  Stop dividing at random points  Immune system normally recognizes

 If avoid regulation, from tumor, unregulated mass of normal tissue  Benign tumor: remain at this original site and can be completely removed  Malignant tumor: invasive, impair normal function of organs, cancer

Properties of Malignant tumors

 Anomalous cell cycle,  Unusual chromosome #  Lost attachment to neighboring cells, may cause separation from original tumor  Migrating cells invade other parts of body, form more tumors  Spread is call metastasis