2 Cell Theory Cells are the fundamental (smallest) units of life. All organisms are composed of cells.All cells come from preexisting cells. (Proved by Pasteur who disproved spontaneous generation in 1859.)Spontaneous GenerationFormulated in 1838 by Schwann and Schleiden.
3 Surface area to volume ratio Cells have a large surface area to volume ratio.The cell’s volume determines the rate of chemical activities over time.The cell’s surface area determines the amount of substances a cell can take in an expel.Because cells need to transport substances frequently, small size is essential.How do you increase cell SA without increasing size?
4 SA Increase the folding to increase SA. The respiratory tract has the SA of a tennis court due to folding…The intestines has the SA of a football field….The excretory system has large SA for N removal:Ammonia in fishUrea in humans and animalsUric acid in birds and reptiles
6 Digestive Tract Small Intestine averages 23 feet.
7 Villi and Microvilli on the interior of the small intestine KeyNutrientabsorptionVein carrying bloodto hepatic portalvesselMicrovilli(brush border)BloodcapillariesEpithelialcellsMuscle layersEpithelial cellsLargecircularfoldsLactealVilliLymphvesselVilliIntestinal wall
14 Since cells are small we need ocular assistance… Most cells are < 200 μm in size.Minimum resolution of human eye is 200 μm.Resolution is the distance apart that two objects must be in order for the eye to view them as distinct not a blur.Microscopes improve resolution.
18 Types of MicroscopesLight microscopes- glass lens and visible light to form a magnified image of an object. Magnifies about 1000x.Electron microscopes-uses electromagnets to focus an electron beam. The beam is then directed to a fluorescent screen/photographic film to create a visible image. Magnifies about 1,000,000x. Can see subcellular.
20 Cell Similarities1. All cells have a cell membrane. (Phospholipid bilayer.)2. All cells contain DNA.
21 Cell Membrane Structure 1. Phospholipids- are amphipathic. They line up to form a barrier from the water that is inside/outside the cell.Remember Phosphate heads are (-)Phosphates prevent hydration shells around each phospholipid.2. Proteins- are amphipathic.A. Integral run through c.m. Function: structure and transportB. Peripheral- on one side of c.m. Function: attachment of cytoskeleton and ECM
26 C.M. Proteins Cont.The proteins of the cell membrane can have several functions.Molecule transport (Helps move food, water, or something across the membrane.)Act as enzymes (To control metabolic processes.)Cell to cell communication and recognition (So that cells can work together in tissues.)Signal Receptors (To catch hormones or other molecules circulating in the blood.)
27 Membrane Protein Functions SignalEnzymesReceptorATPTransportEnzymatic activitySignal transduction
28 Membrane Protein Functions Glyco-proteinCell-cell recognitionIntercellular joiningAttachment to thecytoskeleton and extra-cellular matrix (ECM)
29 C.M. Cont.3. Cholesterol- keeps c.m. flexibility. Also prevents plant cell membranes from freezing
31 Synthesis Question (U1,D12) Question: All living cells have to have a cell membrane to remain living and intact. All cells are mostly water inside the cell. Cells live mainly in a watery environment. Water is a polar molecule. In four sentences or less, how does the presence of water on the inside and outside of a cell contribute to the structure of cell membranes? (5 Points)1pt. Discussion of negative phosphorus atoms, of phospholipids being attracted to water and forming a barrier in the bi-layer.1pt. Discussion of the bi-layer needed to prevent water from forming hydration shellsaround the phospholipids.1pt. Discussion of the fatty acid tails being protected sandwiched in-between the Phosphorus barriers.1pt. Correct use of scientific terms.1pt. Answer has no more than three sentences. (Following Directions.)
32 Prokaryotic Cells “Kary” means kernel, in this case the nucleus. Prokaryotes compose the Domains: Archaea and Bacteria.Do not have membrane bound organelles.Thought to have been the “first cells”
33 Prokaryotes Can live in more diverse environments than eukaryotes. Can sustain life on more diverse energy sources than eukaryotes.Typically smaller than eukaryotes.Tend to aggregate in chains or clusters.
34 Prokaryote Composition 1. Plasma membrane regulating incoming/outgoing substances.2. Nucleiod- contains DNA, not a defined region3. Cytoplasm: (2 parts)Cytosol-consists mostly of water with ions and water soluble molecules such as proteinsInsoluble particles including ribosomes.Ribosomes are RNA and proteins.
35 Specialized Prokaryotic Features Some prokaryotes developed specialized features. Why?1. Cell Walls- located exterior to the cell membrane. Dissimilar to plant cell wallsCell walls typically contain peptidoglycan an amino sugarSometimes have an outer membrane.Sometimes a capsule:= Slime layer made of polysaccharides; prevents drying out and aids in attachment to other cells (sickness)
37 Cell Walls, Internal Membranes, & Flagella and Pili Plasma membrane will fold in to form specialized compartments for photosynthesis, cell division, or catabolic activities.Structures of MovementFlagella- made of protein flagellin, rotates like an axel for movement.Pili- aka cilia, hairlike projections for movement
40 Cytoskeleton- helical structures just inside the plasma membrane. Composed of proteins similar to actin. Actin makes up cytoskeleton in eukaryotes.Cytoskeleton commonly found in rod shaped bacteria.
42 Eukaryotic Cells Eukaryotic cells ~10x bigger than prokaryotes. Have membrane bound organelles.Organelle can be membrane bound or not.Organelles have a specific functions and shapes.The role/function of an organelle is defined by the chemical reactions that take place
43 Cell fractionation and microscopy Cell organelles first detected by light microscopes.Cell fractionation-break down plasma membrane, organelles separate based on size/density.Biochemical analysis can then be done to detect for certain macromoleculesMany organelles identical in plants and animals.
45 Nucleus Typically the largest organelle in animal cells. Site of DNA (chromatin vs. chromosome).Nucleolus- site of RNA and ribosome synthesis.
46 Nuclear StructureSurrounded by a double membrane called the nuclear envelope.~3500 nuclear pores exist in the envelopeThe pores consist of over 100 different proteinsThese proteins will aggregate in pore complexes of 8 proteins.Small molecules can get into the pores, larger molecules need a nuclear localization signal. (chain of amino acids)
47 Figure 4.8 The Nucleus is Enclosed by a Double Membrane (Part 2)
48 Figure 4.8 The Nucleus is Enclosed by a Double Membrane (Part 1)
49 Ribosomes- NOT ORGANELLES Function: protein synthesis per nucleic acid instructionsLocation:Attached to Endoplasmic reticulum-out of cell proteins,free-floating in cytoplasm-in cell proteinsinside mitochondria and chloroplasts.Composed of two different subunits:rRNA- ribosomal RNAProtein molecules (>50 different ones)
50 Endomembrane SystemMade up of Endoplasmic Reticulum and Golgi Bodies/ApparatusVesicles serve as transporters of substances between the endomembrane structure and within the cell.
51 Endoplasmic Reticulum Location: extends from the outer membrane of the nuclear envelope.Two Types: RER,SERBecause of its many folds it has a surface area greater than the cell membraneThe interior of the ER is called the lumenTubes are called cisternae
52 Rough Endoplasmic Reticulum It is called rough because ribosomes are temporarily attached .Site of protein synthesisProteins undergo folding within the RERProteins can then be shipped to incorporated endomembranes (GB), other organelles, or extracellular locations.
53 Smooth Endoplasmic Reticulum No ribosomes attachedFunction:Modification of some proteins from RERHydrolysis of glycogenSynthesis of lipids, phospholipids, and steroidsDetoxifies bloodStores calcium
54 What does this mean?Cells that synthesize a lot of proteins have a lot of ER.e.g. Gland cells that secrete enzymes and WBCCells that modify molecules that enter the body (food) have a lot of ERe.g. liver cells have lots of SER
57 Golgi Bodies/Apparatus Flattened membranous sacs called cisternae, think stacks of pancakesFunctions:further modifies proteins by attaching sugars to them so they can leave through the c.m. (glycoproteins)Concentrates, packages, and sorts proteins to be shipped extracellularMakes cellulose/starch for plant cell walls
59 Lysosome Originate from the Golgi bodies Contain digestive enzymes to hydrolyze all 4 macromolecule types (enzymes=lysozymes)When molecules enter through phagocytosis: called the phagosome (vesicle/vacuole with macromolecule)Phagosome attaches to primary lysosome forming a secondary lysosome where digestion takes place
60 Small particles diffuse through cytoplasm Figure 4.12 Lysosomes Isolate Digestive Enzymes from the Cytoplasm (Part 1)Small particles diffuse through cytoplasm
61 Figure 4.12 Lysosomes Isolate Digestive Enzymes from the Cytoplasm (Part 2)
63 Lysosomes and Autophagy Autophagy- organelles are ingested, hydrolyzed, and released into the cytoplasm for reuse.Plant cells do not have lysosomes, but their central vacuole contains digestive enzymes.
65 Mitochondria and Chloroplasts Prior to the mitochondria and chloroplasts, breakdown of fuel molecules begins in the cytosol.Both organelles transform energy from one form to anotherChloroplasts take light energy and convert it into chemical energy.Mitochondria take molecules such as glucose and convert it into a usable form of energy
66 Mitochondria and Cellular Respiration Mitochondria make ATP (adenosine triphosphate) through cellular respiration.Cells that require the most energy have the most mitochondria per volume. (Liver cells have ~1000/cell.)Mitochondria can reproduce by binary fissionContains its own DNA, ribosomes, and enzymesThought to have been purple bacteria.
67 Outer Membrane- little resistance to flow of materials. Figure 4.13 A Mitochondrion Converts Energy from Fuel Molecules into ATPOuter Membrane- little resistance to flow of materials.Inner Membrane- folded (cristae): greater surface area than O.M.Controls flow of substancesEmbedded with proteins to synthesize ATPMatrix- contains enzymes, DNA, and ribosomes
68 Chloroplast Type of Plastid (plastid-pigment container) Located in plants and algaeHave DNA, ribosomes, enzymesReproduce by binary fissionThought to have been blue green algae
72 Peroxisomes Membrane bound organelles that contain toxic peroxides. Peroxides are unavoidable by-products of chemical reactions, that can be safely broken down within the peroxisome.
73 VacuolesMembrane bound organelle filled with an aqueous solution and many solutes.Function:Central-StorageFood vacuoles- in simple eukaryotes, used in lieu of digestive system. Intake of food cause a vacuole which fuses with a lysosome, and chemical energy is released in to the cell.Contractile vacuoles- typically in protists; helps with movement as a result of filling with water because of osmotic pressure differences.
74 Figure 4.18 Vacuoles in Plant Cells Are Usually Large
76 Removes excess water in aquatic single celled organisms
77 Cytoskeleton Not a membrane-bound organelle. Function: Supports and maintains cell shapeProvides for some cellular movementPositions organelles with in the cellsSome fibers can act as tracks that motor proteins can move organelles intracellularlyInteracts with extracellular structures to anchor the cell in place.Types: microfilaments, intermediate filaments, and microtubules
78 Microfilaments-smallest cytoskeleton Can exist alone, in bundles, or networksMade up of actin (protein). These PULL.Microfilaments responsible for:Cytoplasmic streaming- movement of cytoplasmPinching/Mitotic Movement- formation of daughter cellsPseudopodia- “False feet” for movement
79 Intermediate filaments-medium cytoskeleton Fibrous proteins of the keratin family.Function: stabilize cell structure.
80 Microtubules-largest cytoskeleton Function: move organelles or cell.Composed of the protein microtubulin.Examples:Cilia and flagellaCentrosomes/CentriolesSpindle Fibers
82 Anticipatory Set 9-8-11 Organic Compound Monomer Example Function Amino acidFat, oil, waxcarbohydrate
83 Synthesis Questions U1,D16 Question: The one part of evolution tries to show unity and diversity exists among all organisms on earth. All living organisms on Earth are either composed of Prokaryotic cells or Eukaryotic cells. In no more than four sentences, justify unity by stating one cellular structure all organisms have in common and for diversity state two structures that all eukaryotic cells possess that Prokaryotic cells do not possess. For each structure state the structures function within the cell. (5 Points)
84 1pt. (Half point for one of the following: DNA, ribosomes, cell membrane, cytoplasm) (Half point for structures purpose: information, making proteins, Holding celltogether, space to work)1pt. Structure 1 with correct function from following listRER – make proteinsSER – lipids and carb metabolism, detoxificationMitochondria – Making energyChloroplast – Sugar productionGolgi Apparatus – protein modificationVesicles – StorageLysosomes – DigestionCytoskeleton – supportCell Wall or ECM - protection1pt. Structure 2 with correct function1pt. Correct use of scientific terms.1pt. Answer has no more than three sentences. (Following Directions.)
86 Extracellular Matrix Area outside of animal cells Composed of fibrous proteins like collagen and proteoglycans/glycoproteins (proteins + sugar).The extracellular matrix is specific to the tissue type, and is made of proteins and fluids the cells secrete.
87 Function of Extracellular Matrix Holds cells together in tissuesContributes to physical properties of cartilage, skin, and other tissues.Helps filter materials passing between tissues.Helps orient cell movements during embryonic development and tissue repair.Role in chemical signaling.
89 Figure 3.20 Phospholipids (A) Repeat Fig 3.20A here
90 Cell MembraneAll biological membranes consist of lipids, carbohydrates, and proteins.The cell membrane is sometimes referred to as the fluid mosaic model.This is because it prevents a lot of hydrophillic substances from rapidly entering, and embeds a lot of floating proteins.
91 Figure 5.2 A Phospholipid Bilayer Separates Two Aqueous Regions
92 Cell Membrane ContentPhospholipids can vary with respect to fatty acid chain length, degree of unsaturation (presence of double bonds), and phosphate groups present.25% of lipid content can be cholesterol.Most cholesterol in membranes is not detrimental to your health; maintains membrane integrity.
93 Cell Membrane Fluidity Fluidity is affected by:Lipid compositionTemperatureWhen temp. decreases, membrane fluidity decreases. Therefore cellular function decreases.Plants and animals that hibernate may change their lipid content (sat. to unsat. F.A. tails to achieve shorter tails) to survive.Fluidity=Function No Fluidity=No Function
94 Membrane Proteins All membranes have proteins. Two Types of Membrane Proteins:Integral- hydrophobic and hydrophillic regions, located within the membrane. Include transmembrane proteins.Peripheral- only have hydrophillic regions, interact with other hydrophillic regions of other proteins or heads of phospholipids.
95 Transmembrane Proteins Transmembrane proteins are a type of integral protein. Extend out on both sides of the membrane.R groups from amino acids determine hydrophobic/hydrophillic location.Integral proteins are only on one surface of the cell membrane. (Inside or outside)
96 Carbohydrates in Cell Membranes Located on the outer surface of cell membranes.Serve as a recognition site for other cells and molecules.Sometimes carbohydrates fuse with lipids and proteins:Glycoproteins= carbohydratecovalent bond proteinGlycolipid= carbohydrate covalent bond lipid
97 Cell RecognitionCell recognition- one cell specifically binds to another cell of a certain type.An example would be sperm and egg fusing.Homotypic binding- same glycoprotein sticks out of both cells, and the exposed similar carbohydrates bind cells together. eg. tissuesHeterotypic binding- different glycoproteins stick out from cells, but they have an affinity for one another so they bind together. eg. fertilization
98 Cell AdhesionCell Adhesion- the connection between two cells is strengthened.Cell Junction- result of cell adhesion; 3 types.
99 1. Tight JunctionsLink epithelial cells which line organs and inside of mouth.Function of T.J. prevent substances from moving between cells, and dictate the function of each region of the cell.Like a quilted pattern(Controls membrane proteins)
100 2. DesmosomesConnect adjacent cell membranes like a spot weld. Allow substances to move everywhere but the connection.Desmosome attached to intermediate filaments inside each cell
101 3. Gap JunctionsFunction in communication between cells. (Desmosomes and tight junction have mechanical functions.)Connexons are the channel proteins that span between cells and allow for molecules and ions to pass through
103 Theory of Endosymbiosis Prokaryotes first absorbed food through environment.Then Photosynthesis evolved.Larger cells engulfed smaller cells, but smaller cells were not digested.The smaller cell divided along with the bigger cell.The big cell provides protection, the little cell provides energy.1980s, Margulis suggests endosymbiosis of chloroplast and mitochondria because they have their own circular DNA, ribosomes, and same size as prokaryotes.
104 Endosymbiosis Theory is strengthened by: Prokaryotes and eukaryotes share:Nucleic acids as genetic materialSame 20 amino acids in protein structureD sugars and L amino acids
105 2011 Released Essay Prokaryote vs. Eukaryote Scoring Guide