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Figure 5.1 Fibers of extracellular matrix (ECM) Enzymatic activity Phospholipid Cholesterol CYTOPLASM Cell-cell recognition Glycoprotein Intercellular.

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Presentation on theme: "Figure 5.1 Fibers of extracellular matrix (ECM) Enzymatic activity Phospholipid Cholesterol CYTOPLASM Cell-cell recognition Glycoprotein Intercellular."— Presentation transcript:

1 Figure 5.1 Fibers of extracellular matrix (ECM) Enzymatic activity Phospholipid Cholesterol CYTOPLASM Cell-cell recognition Glycoprotein Intercellular junctions Microfilaments of cytoskeleton ATP Transport Signal transduction Receptor Signaling molecule Attachment to the cytoskeleton and extracellular matrix (ECM)

2 Passive transport  Passive transport = diffusion across cell membrane –No energy required!!  Moves with concentration gradient  Examples: –Urea, CO2, O2, Water, small hydrophobic © 2012 Pearson Education, Inc. Animation: Membrane Selectivity Animation: Diffusion

3 Figure 5.3A Molecules of dye Membrane Pores Net diffusion Equilibrium

4 Figure 5.3B Net diffusion Equilibrium

5 © 2012 Pearson Education, Inc. Osmosis Solute molecule with cluster of water molecules Water molecule Selectively permeable membrane Solute molecule H2OH2O Lower concentration of solute Higher concentration of solute Equal concentrations of solute Osmosis = diffusion of water across a membrane

6 Figure 5.5 Animal cell Plant cell Turgid (normal) Flaccid Shriveled (plasmolyzed) Plasma membrane Lysed NormalShriveled Hypotonic solution Isotonic solution Hypertonic solution H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O

7 Osmoregulation = Water Balance  Osmoreguatation = all organisms must regulate internal water concentrations to remove excess water or prevent water loss –Remove excess water: –Contractile vacuoles - protists –Freshwater organisms – kidneys, gills –Prevent water loss: –Guard cells in plants © 2012 Pearson Education, Inc. Video: Paramecium Vacuole Video: Chlamydomonas Video: Turgid Elodea Video: Plasmolysis

8 Facilitated Diffusion = Passive diffusion of solute using a transport protein Solute molecule Transport protein Only moves solutes with concentration gradient! Examples: ion channels, aquaporin

9 5.7 SCIENTIFIC DISCOVERY: Research on another membrane protein led to the discovery of aquaporins  Dr. Peter Agre received the 2003 Nobel Prize in chemistry for his discovery of aquaporins.  His research on the Rh protein used in blood typing led to this discovery. © 2012 Pearson Education, Inc.

10 Figure 5.7

11 Active Transport  In active transport, a cell –must expend energy to –move a solute against its concentration gradient.  The following figures show the four main stages of active transport.  Examples: Na-K-ATP Pump, H+ Pump, Na- Glucose Cotransporter © 2012 Pearson Education, Inc. Animation: Active Transport

12 Figure 5.8_s4 Transport protein Solute ADP ATP P P P Protein changes shape. Phosphate detaches. Solute binding Phosphate attaching TransportProtein reversion 4 32 1



15 5.9 Exocytosis and endocytosis transport large molecules across membranes  There are three kinds of endocytosis. 1.Phagocytosis is the engulfment of a particle by wrapping cell membrane around it, forming a vacuole. 2.Pinocytosis is the same thing except that fluids are taken into small vesicles. 3.Receptor-mediated endocytosis uses receptors in a receptor-coated pit to interact with a specific protein, initiating the formation of a vesicle. © 2012 Pearson Education, Inc. Animation: Phagocytosis Animation: Exocytosis Animation: Receptor-Mediated Endocytosis Animation: Pinocytosis Animation: Exocytosis and Endocytosis Introduction

16 Figure 5.9 Phagocytosis Pinocytosis Receptor-mediated endocytosis EXTRACELLULAR FLUID CYTOPLASM Pseudopodium “Food” or other particle Food vacuole Food being ingested Plasma membrane Vesicle Receptor Specific molecule Coated pit Coated vesicle Coat protein Coated pit Material bound to receptor proteins

17 ENERGY AND THE CELL © 2012 Pearson Education, Inc.

18 5.10 Cells transform energy as they perform work  Energy = capacity to cause change or to perform work.  Two kinds of energy: 1.Kinetic energy is the energy of motion. 2.Potential energy is energy that matter possesses as a result of its location or structure.  Heat = thermal energy  Chemical energy = potential energy available in bonds within molecules and released in a chemical reaction. –Most relevant energy to living organisms © 2012 Pearson Education, Inc. Animation: Energy Concepts

19 Figure 5.10 Fuel Energy conversion Waste products Gasoline Oxygen Glucose     Heat energy Combustion Kinetic energy of movement Energy conversion in a car Energy conversion in a cell Energy for cellular work Cellular respiration ATP Heat energy Carbon dioxide Water

20 Thermodynamics = study of energy transformations  First law of thermodynamics = energy in the universe is constant –Biological organisms cannot produce energy - only convert forms of energy  Second law of thermodynamics = energy conversions increase the disorder (entropy) of the universe. –No energy transformations are 100 % efficient –Usuable energy lost as heat –Energy transformations are one-way street –Biological organisms require constant supply of energy to maintain order!! © 2012 Pearson Education, Inc.

21 Metabolism = total of an organism’s chemical reactions  Chemical reactions are either –Exergonic reactions release energy. –These reactions release the energy in covalent bonds of the reactants. –Cellular respiration  An endergonic reaction –requires an input of energy; products contain more chemical/potential energy –Photosynthesis  Energy coupling = energy released from exergonic reactions drive endergonic reactions!! © 2012 Pearson Education, Inc.

22 Figure 5.11A Reactants Energy Products Amount of energy released Potential energy of molecules

23 Figure 5.11B Reactants Energy Products Amount of energy required Potential energy of molecules

24 Cells need energy to perform work!!  There are three main types of cellular work: 1.chemical 2.mechanical 3.transport  ATP drives all three of these types of work. © 2012 Pearson Education, Inc.

25 ATP = Adenosine triphosphate © 2012 Pearson Education, Inc. Adenine P P P Phosphate group ATP:Adenosine Triphosphate Ribose

26 Figure 5.12A_s2 ADP: Adenosine Diphosphate P P P Energy H2OH2O Hydrolysis Ribose Adenine P P P Phosphate group ATP:Adenosine Triphosphate

27 ATP drives cellular work  Hydrolysis of ATP releases energy by transferring phosphate from ATP to some other molecule –phosphorylation. © 2012 Pearson Education, Inc.

28 Figure 5.12B ATP ADP P P P P P P P P P Chemical work Mechanical workTransport work Reactants Motor protein Solute Membrane protein Product Molecule formed Protein filament moved Solute transported

29 How Does Cell Regenerate ATP? © 2012 Pearson Education, Inc. Energy from exergonic reactions Energy for endergonic reactions ATP ADP P  ATP = renewable source of energy for the cell.  ATP cycle = energy released in an exergonic reaction is used in an endergonic reaction to generate ATP.

30 HOW ENZYMES FUNCTION © 2012 Pearson Education, Inc.

31 Enzymes = Organic catalysts  Increase RATE of chemical reaction by decreasing activation energy (E A ). –E A = energy barrier must be overcome before any chemical reaction can begin. © 2012 Pearson Education, Inc. Activation energy barrier Reactant Products Without enzyme With enzyme Reactant Products Enzyme Activation energy barrier reduced by enzyme Energy Animation: How Enzymes Work

32 Reactants Products Energy Progress of the reaction a b c Enzymes Only Increase RATE of reaction, NOT the energy Level of reactants or products!!!

33 A specific enzyme catalyzes each cellular reaction  An enzyme –Is specific in substrate(s) it binds –And reaction it catalyzes  Substrate = reactant  A substrate binds at enzyme active site.  Enzymes are specific because their active site fits only specific substrate molecules –Active site is result of 3D folding of protein © 2012 Pearson Education, Inc.

34 4 32 1 Products are released Fructose Glucose Enzyme (sucrase) Active site Enzyme available with empty active site Substrate (sucrose) Substrate binds to enzyme with induced fit Substrate is converted to products H2OH2O Catalytic cycle of an enzyme

35 Factors that Effect Enzyme-Catalyzed Reactions  For every enzyme, there are optimal conditions under which it is most effective. –Temperature –pH –Substrate Concentration –Enzyme Concentration –Cofactors/coenzymes –Inhibitors © 2012 Pearson Education, Inc.

36 Factors that Affect Enzyme-Catalyzed Reactions  Many enzymes require nonprotein helpers called cofactors, which –bind to the active site and function in catalysis. –Inorganic molecules  Coenzymes –Organic molecule that acts as cofactor © 2012 Pearson Education, Inc.

37 Enzyme Concentration

38 Substrate Concentration

39 Temperature - affects molecular motion

40 pH

41 Enzyme inhibitors can regulate enzyme activity  Inhibitor = chemical that interferes with an enzyme’s activity. © 2012 Pearson Education, Inc. Substrate Enzyme Allosteric site Active site Normal binding of substrate Competitive inhibitor Noncompetitive inhibitor Enzyme inhibition  Competitive inhibitors –block substrates from entering the active site and –reduce an enzyme’s productivity.  Noncompetitive inhibitors –bind to the enzyme somewhere other than the active site, –change the shape of the active site, and –prevent the substrate from binding.

42 Feedback inhibition Starting molecule Product Enzyme 1 Enzyme 2 Enzyme 3 Reaction 1 Reaction 2 Reaction 3 A B C D  Enzyme inhibitors are important in regulating cell metabolism. –Feedback inhibition = product of metabolic pathway acts as an inhibitor of one of the enzymes in the pathway

43 1.Describe the fluid mosaic structure of cell membranes. 2.Describe the diverse functions of membrane proteins. 3.Relate the structure of phospholipid molecules to the structure and properties of cell membranes. 4.Define diffusion and describe the process of passive transport. You should now be able to © 2012 Pearson Education, Inc.

44 5.Explain how osmosis can be defined as the diffusion of water across a membrane. 6.Distinguish between hypertonic, hypotonic, and isotonic solutions. 7.Explain how transport proteins facilitate diffusion. 8.Distinguish between exocytosis, endocytosis, phagocytosis, pinocytosis, and receptor-mediated endocytosis. You should now be able to © 2012 Pearson Education, Inc.

45 9.Define and compare kinetic energy, potential energy, chemical energy, and heat. 10.Define the two laws of thermodynamics and explain how they relate to biological systems. 11.Define and compare endergonic and exergonic reactions. 12.Explain how cells use cellular respiration and energy coupling to survive. You should now be able to © 2012 Pearson Education, Inc.

46 You should now be able to 13.Explain how ATP functions as an energy shuttle. 14.Explain how enzymes speed up chemical reactions. 15.Explain how competitive and noncompetitive inhibitors alter an enzyme’s activity. 16.Explain how certain drugs, pesticides, and poisons can affect enzymes. © 2012 Pearson Education, Inc.

47 Table 5.UN05

48 Figure 5.UN06 pH Rate of reaction 10 9 87 6 54 3 21 0

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