Monday September 29 12/12/08 6:55 PM Population Biology Exponential growth model ? geometric increase of a population as it grows in an ideal, unlimited environment. G=rN G = growth rate N = number of individuals r= per capita rate of increase if r is small: high death rate, low birth rate individuals not reproducing, sex ratio skewed toward males and short generation time N and r determine the rate at which population increases Population-limiting factors - Controls population size Density-dependent controls Depends on population density With a high population density, causes changes in fecundity (# offspring/time) and survivorship because with high population, limited resources etc Also, diseases that are passed from one individual to another are passed more readily with higher population size ? higher population density Density-independent controls Size/density is not important Factors such as weather, soil pH When population limits set in? Population sizes can crash To extinction or near-extinction Populations can stabilize Logistic Growth Model ? idealized population growth that is slowed by limiting factors Growth rate will be small when population size is either large or small Growth rate with be highest with population is at n intermediate level relative to K At low population levels, if resources are abundant, the population is able to grow exponentially Density-dependant controls important for K strategists K-selected population size is near carrying capacity due to density dependant factors Density-independent controls important for r-strategists r-selected environmental instability reduces population size before it approaches carrying capacity Zoo Final 12/12/08 6:55 PM Communities! Predation defenses Cryptic coloration = camouflage Coloration that is hard to see Faker Batesian mimicry = pretend to be an animal that is poisonous Faker Aposematic coloration Bright colors, means poisonous Truth teller Mullerian mimicry Truth teller Lots of species that are all the same colors, all bad to eat Strength in numbers Symbiosis ? interaction between two different species that involves direct Physical contact Mutualism ? both benefit Commensalism ? one benefits, other neutral ?hitch hiker? Parasitism ? one benefits, host is harmed Competition ? lose/lose Competitive exclusion principle ? two species that share the same limiting resources cannot coexist indefinitely Fundamental niche = all resources it can possibly use ? BIG Realized niche = all resources it actually uses ? SMALL Resource partitioning to avoid competition Character displacement ? greater differences in a trait with two species co-occur than when either is present by itself ? to avoid competition Keystone species ? species that has a disproportionate effect on its environment relative to its abundance Often identified by removal experiments Ex. Sea Star = keystone, keeps mussel (dominant species) under control Keystones make sure dominants don?t exhaust resources Ecosystem ?engineers? / foundation species Species that cause physical change in environment Monday September 15 12/12/08 6:55 PM Ecosystem ? living community and non-living environment with which it interacts The energetic hypothesis ? energy transfer along chain is inefficient, limiting chain length Gross primary production ? amount of light energy converted to chemical energy Energy now available for plants to use to carry out their life activities, and heterotrophs use to carry out their life activates Friday September 19 12/12/08 6:55 PM =Net primary production Monomers = small subunit molecules Many monomers = polymer Enzymes needed to disassemble polymers Carbohydrates (sugars) Monomer = monosaccharide (simple sugar) Sugars are broken down for quick energy Many monosaccharides = polysaccharides Complex carbs Polysaccharides are made of all glucose monomers Functions of Polysaccharides 1. Energy storage Starch Glucose 2. Structure Cellulose Chitin 3. Signaling and recognition Glycoprotein Proteins Monomer = amino acid Amino + amino = dipeptide Lots = polypeptide Primary (1°) Structure Linear sequence of amino acids Zigzag folding Secondary (2°) Structure Localized folding ? helix = coil ?-pleated = localized zigzag folding Tertiary (3°) Structure Globular conformation Chaperones Proteins that assist in folding of other proteins Quaternary (4°) Structure Some proteins are composed of two or more distinct polypeptides Subunits How an Enzyme works Biological catalysts that speed up rates of reactions without being consumed Specific to each reaction Substrate (sugar) comes in and binds to active site pockets of the enzyme, making a enzyme-substrate complex Enzyme breaks bonds on substrate, giving products Lipids (fats) Hydrophobic Vital to life Growth, utilization of some vitamins, insulation, cushion organs, excellent energy source, major component of cell membranes Waxes form barriers to water loss Waterproof fur, feathers, leaves, fruits, stems Sterols have many functions ? steroids Stabilize membranes Hormones (estrogen, testosterone) Good and bad cholesterol LDL = LOUSY HDL = HAPPY Fats and oils are triglycerides that store energy Glycerol?s have fatty acids binded to it Very hydrophobic Saturated v unsaturated Unsaturated have C=C Polyunsaturated have multiple C=Cs Saturated = bad, unsaturated = good Cis is good and trans is bad Phospholipids ? components of cell membranes with water trapped inside Basis of biological membrane Hydrophilic membranes with hydrophobic phospholipids bi-layer Monday September 22 12/12/08 6:55 PM Biological Membranes Have phospholipid bilayer, proteins and sterols Glycoprotein ? have polysaccharides attached, always outside the cell Transmembrane proteins Peripheral proteins ? inside of cell on plasma membrane Sterols ? make up membrane Phospholipids ? move freely within their half of the bilayer (laterally) Functions of membrane proteins Transport Enzymatic activity Signal transduction (cancer, hormones) Intercellular joining (intestine) Cell-cell recognition (immune system) Membrane Transport Simple diffusion Facilitated diffusion Osmosis Active transport Bulk transport Simple diffusion ? passive transport Requires no energy in the form of ATP DOWN the concentration gradient From high to low concentrations Small hydrophobic molecules Gases ? O2 and CO2 Sterols Facilitated diffusion ? passive transport No energy required DOWN the concentration gradient Protein needed! Channel proteins Many are gated! Something binds to the protein, signaling to open the gated channel Open/close in response to specific signal Carrier proteins Conformational change Carrier binds selectively Channel opens, non selective movement Osmosis ? passive transport of water Water moves down the concentration gradient It moves until equal concentration on both sides of the membrane Combination of simple and facilitated diffusion Aquaporins are the water channels Active transport ? energy required AGAINST the concentration gradient! That?s why energy is a must! ATP comes in to activate pumps Transport stuff ? movement of large = bulk transport process Exocytosis = OUT of the cell Endocytosis = INTO the cell Phagocytosis = cell eating Enter cell, eventually fusing with lysosomes Destroyed Pinocytosis = cell drinking Drinks dissolved molecules Receptor-mediated-endocytosis = internalization of specific substances Wednesday September 24 12/12/08 6:55 PM Receptor is required! Cells = fundamental unit of life Perform all life activities Extract and use energy Reproduce Homeostasis Maintain constant internal environment Respond to environment Prokaryotic cells Nucleoid ? central bundle of goods Ribosomes ? dots, where proteins are synthesized Plasma membrane Cell wall ? surrounds everything! Even plasma membrane Pili ? little squiggly things all over the cell Flagella ? tails Bacterial chromosome DNA ? part of Nucleoid. Squiggly stuff Extremophiles ? the other prokaryote Methanogens O2-free environments Extreme thermophiles Extremely hot (230F) Extreme halophiles Extremely salty conditions Eukaryotes ? have organelles Organelle = membrane bound compartment Each has distinct function Characteristic set of enzymes Specialized molecules Nucleus = information control center Nuclear envelope = encases nucleus Chromatin = inside stuff, DNA + Protein Nucleolus = innermost part, where ribosomes are made Nuclear pores = where things can enter the nucleus Nuclear Localization Signal = proteins that get imported into the nucleus have an NLS Is a specific sequence of amino acids ?Cellular Zip code? Nuclear lamina = part of nuclear envelope Structural integrity of nucleus
Want to see the other 12 page(s) in Zoo Final pt 1?JOIN TODAY FOR FREE!