BIOL110s05-13 - BIOL 110 Principles of Biology Spring 2005...

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Unformatted text preview: BIOL 110: Principles of Biology Spring 2005 Lecture 13, W 2/23/05 http://www.smccd.net/accounts/staplesn/biol110/ Note: You MUST physically complete each laboratory exercise to get credit for lab attendance. ie: just coming in to take the quiz, etc. doesn't cut it!!! ie: doesn' Midterm #1: Average 75%, Median 82%; 3 at 100%+ See me ASAP (by next Fri.), if you scored < 70%. (Don't panic!!) (Don' Extra Credit if <70%: Rewrite wrong multiple choice questions, explaining why your choice was wrong, and the correct answer is right. (earn-back up to 50% of lost points on M/C) (earn- NO LABS this week!!! Return Lab Quiz #1 to me. me. Journal Article reports ... Topics due 3/7 or 3/9 in lab. The Caada Scholarship deadline is Wed., March 2nd. For Ca help with your personal statement, the Learning Center is having two workshops: Personal Statement Workshop for Your Scholarship Application Wednesday, February 23 from 12:15 to 1:00 Thursday, February 24 from 12:15 to 1:00 REVIEW: Ch. 4: How Cells Work Enzymes & regulation (catalysis, substrates, active sites, activation energy) Regulation: Induced fit, Allostery pH, Temp, Substrate concentration, salt conc'n, etc. conc' TODAY: Ch. 4: How Cells Work Membrane Transport Passive Simple Diffusion, Facilitated Diffusion Active: Thru protein transporter, or bulk Ch. 5: Photosynthesis Where it Starts Chloroplasts, Light & Pigments 1 III. Membrane Transport: Concentration Gradient Means the number of molecules or ions in one region is different than the number in another region a substance moves from a region where it is more concentrated to one where it is less concentrated: "down" gradient (High down" oxygen, carbon dioxide, and other small, nonpolar molecules; some water molecules Low concentration) glucose and other large, polar, water-soluable molecules; ions water(e.g., H+, Na+, K+, CA++, CI); water molecules CI Selectively Permeable Barrier PASSIVE TRANSPORT (1) A. Simple Diffusion The net movement of like molecules or ions down a concentration gradient molecules collide randomly, but net movement is away from the place with the most collisions (down gradient) 2 Factors Affecting Diffusion Rate 1. Steepness of concentration gradient Steeper gradient, faster diffusion 2. Molecular size Smaller molecules, faster diffusion 3. Temperature Higher temperature, faster diffusion 4. Charge (like ions strongly repel each other) 5. Electrical or pressure gradients B. Transport Proteins: Facilitated Diffusion transport protein with binding site for molecule or ion of a specific substance (the solute) (Passive Transport - 2) Proteins span pan the lipid bilayer Interior is able to open to both sides Change shape when they interact with solute Move water-soluble substances across a membrane solute lipid bilayer of cell membrane 3 C. Passive and Active Transport Passive Transport Doesn't require energy inputs Solutes diffuse through a channel inside the protein's interior (facilitated) Active Transport Requires ATP Protein is an ATPase pump Pumps solute against its concentration gradient Low High Net movement is down concentration gradient High Low Membrane Transport high Concentration gradient ATP low Diffusion of lipidlipidsoluble OR very small substances - SIMPLE Passive transport of water-soluble watersubstances - FACILITATED Active transport through ATPase -CONSUMES ATP: -Low High 4 D. Osmosis Water molecules tend to diffuse down water concentration gradient Total number of molecules or ions dictates concentration of water Tonicity: relative solute concentration of two fluids 1. Hypertonic - having more solutes 2. Isotonic - having same amount 3. Hypotonic - having fewer solutes Tonicity and Osmosis 2% sucrose hyper water 10% sucrose 2% sucrose Hypo- Hyper- Iso- hypo 5 Hydrostatic Pressure Pressure that a fluid exerts against structure enclosing it (wall, membrane) Eg: Turgor Pressure in plants Increases with increased solute concentration Influences the osmotic movement of water Increase in Fluid Volume compartment 1 compartment 2 HYPOTONIC SOLUTION membrane permeable to water but not to solutes HYPERTONIC SOLUTION fluid volume increases In compartment 2 6 F. Membrane Traffic (Bulk Transport) Endocytosis Membrane sinks inward around a substance, bringing it into the cell in a vesicle Phagocytosis; Phagocytosis; Pinocytosis cytoplasm Exocytosis Vesicle carrying substance fuses with membrane, releasing it into the intracellular fluid plasma membrane Cyclical processes!!! cytoplasm Animation Endocytosis and Exocytosis (Other types of Active Transport) Click to view animation. 7 Chapter 5 Where It Starts: Photosynthesis Carbon and Energy Sources Photoautotrophs ("self-feeders with light") Producers!! Carbon source is carbon dioxide Energy source is sunlight Heterotrophs ("feed on others") Consumers!! Get carbon and energy by eating autotrophs or one another 8 Photoautotrophs Capture sunlight energy and use it to carry out photosynthesis Plants Some bacteria Many protistans Linked Processes Photosynthesis Energy-storing pathway Releases oxygen Requires carbon dioxide Aerobic Respiration Energy-releasing pathway Requires oxygen Releases carbon dioxide 9 I. Chloroplasts Organelle of photosynthesis in plants and algae (protista) (protista) PS rxns occur in the thylakoid stacks (grana) (grana) Photosynthesis Equation LIGHT ENERGY 12H2O + 6CO2 water carbon dioxide 6O2 + C2H12O6 + 6H2O oxygen glucose water Two Stages of Photosynthesis sunlight H2O energy (water) CO2 (carbon dioxide) ATP lightdependent reactions ADP + Pi NADPH NADP+ lightindependent reactions glucose Suc, Starch, Cellulose Suc, O2 H2O (metabolic water) 10 Visible Light Wavelengths humans perceive as different colors (Minor part of electromagnetic/EM spectrum!) Violet (380 nm) to red (750 nm) Longer wavelengths, lower energy Highest energy photons (packets of light energy) = shortest wavelengths wavelengths Pigments Light-absorbing molecules Absorb some wavelengths and transmit others Color you see are the wavelengths NOT absorbed chlorophyll a chlorophyll b Wavelength (nanometers) 11 Pigment Structure 1. Light-catching part of molecule Light alternating single and double bonds 2. These bonds contain electrons capable of being moved to higher energy levels by absorbing light 3. Excitation of electrons occurs only when the quantity of energy in an incoming photon.... photon... matches the amount of energy necessary to boost the electrons of that specific pigment 4. Amount of energy needed varies among pigment molecules Variety of Pigments 1. 2. 3. 4. Chlorophylls a and b Carotenoids Anthocyanins Phycobilins Chlorophylls Main pigments in most photoautotrophs Wavelength absorption (%) chlorophyll a chlorophyll b Wavelength (nanometers) 12 ...
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