DIVERSITY OF LIFE Diversity: how many and what types The origin and radiation of life: history of life on earth, Fig 26.3 Yard stick history of life: 1000 million = 1 billion 1 in = one hundred million years or 100,000,000 years 39 inches = 3900 million yrs or 3.9 billion yrs The age of the earth: first life (prokaryotes) 4.5 billion 4,500,000,000 35” or 3.5 billion or 3,500,000,000 eukaryotic cells 15” multicellular 7.0” 1st vertebrates 4.5” plants invade land dinos 2.5” angiosperms 1” dino’s extinct 0.65” 4” A 12” ruler is long enough for all multicelluar organisms- A 6” ruler is long enough for most of our fossil record of plants and animals Fig 26.1 How many kingdoms are there? Fig 26.16 Protista More diverse than plants, animals or fungi aquatic Autotrophic or heterotrophic (i.e., algae and protozoa) Multicellular or unicellular (brown kelp, seaweeds, plankton) Reproduce sexually using all known types of sexual life cycles Eukaryotes that are not animals, plants, or fungi What are animals? Most phyla are aquatic (33) but a few important ones are terrestrial multicellular eukaryotes; heterotrophic and take in energy/food thru ingestion store carbohydrate as gycogen lack cell walls nervous tissue and muscle tissue diploid stage of life cycle dominate What are plants? terrestrial (but, including secondarily aquatic plants: i.e., water lilies), multicellular, photosynthetic, eukaryotic haploid or diploid stage dominate What are fungi? terrestrial multicellular, heterotrophic by absorption eukaryotic haploid stage dominates You are responsible for knowing what Phylum and something about every creature we talk about in lecture or see in the lab. Animal structure and function examine adaptations to deal with problems faced by animals: acquiring energy exchange of gases with environment finding mates (and reproducing on land) preventing dehydration for terrestrial species All living things require energy plants use solar energy animal energy source? energy held in bonds of molecules in other organisms bodies what happens when bonds broken? energy captured in ATP what happens to atoms of molecules? biosynthesis of new molecules or excreted summary of bioenergetics in animals in Fig 40.10 Living things exchange materials (matter) with environment contrast aquatic vs terrestrial organisms surface area to volume ratio impacts exchange (Fig 40.7) terrestrials must reduce surface area to volume as surface area/volume decreases need internal circulatory system Fig 40.8 specialized exchange surfaces, for example see small intestine of mammal (fig 41.19,) large folds of epithelium surface of folds covered with smaller villi cells of villi covered with extentions surface area of human small intestine is 300 m2, the size of a tennis court Energy budgets show how animals use energy and materials (energy and matter) metabolic rate is energy used per unit time How do you measure it? What is energy; give some examples What is matter; give some examples Total energy expended per year depend on an animals size and metabolic rate (fig. 40.13) What is the advantage of being an ectotherm? What is the advantage of being an endotherm? Do larger or smaller organisms have lower energy costs per kilogram? Fig 40.13 Homeostasis maintains nearly constant internal environment Circulation of gases and nutrients gastrovascular cavity in cnidarians, planarians arthropods and mollusks have open circulatory system not blood, but hemolymph fig 42.2 some invertebrates (annelids) and vertebrates have closed circulatory systems like open system they have a heart, but add more vessels and capillaries see Fig 42.8. Arteries are narrow diameter, with thicker muscular layer than veins. Capillaries are small diameter with epithilium and basement membrane only. gas and nutrient exchange occurs in capillaries; thin and blood moves slowly although capillaries smaller diameter, they have greater cross sectional area, accounting for slower blood volume (see Fig 42.10) valves in veins insure one way flow through low pressure areas blood and lymph are related but distinct in closed systems capillaries are leaky; water and small molecules escape into interstitial areas (red blood cells and proteins remain inside) interstitial fluid is collected by lymph system, call it lymph; returned to circulatory system lymph nodes filter bacteria and viruses by maintaining high populations of white blood cells as metabolism of vertebrate increases, chambers in heart increase from 2 in fish to 4 in mammals and birds (Fig 42.3) what selective advantage did creatures with more chambers in their hearts have over their ancestors with fewer chambers (i.e., amphibian type animals with 3 chambers of fish like ancestors with only 2 chambers or birds and mammals with four chambered hearts have over their ancestors with only 3 chambered hearts?) Gas exchange Three factors impact gas exchange system 1. metabolic rate gas exchange and circulatory system together provide oxygen for cellular respiration(Fig 42.18) 2. surface area-volume ratio as surface area-volume ration decreases as animals get bigger, they require specialized respiratory surfaces that increase surface area for gas exchange 3. gas exchange in water versus air oxygen is more concentrated in air than water (air is 21% oxygen) diffusion of gases must occur across moist surface in air, gas exchange results in loss of water water contains dissolved oxygen, but much less concentrated than in air (5 mL per liter of water…that’s only 0.5% oxygen; air would have 200mL per liter) cold water holds more dissolved oxygen than warm water flowing water captures more oxygen than still water AQUATIC ANIMALS: gills are outfoldings of body surface adapted for gas exchange water (Fig 42.19) increase surface area arthropods and annelids often have thin flap of gill for each segment fish have gills associated with pharengeal slits gills of fish are very efficient at removing oxygen from water countercurrent exchange (Fig. 42.20 and 42.21) extract 80-90% of oxygen in water TERRESTRIAL ANIMALS: internal structures connected to outer air thru narrow openings are adaptations for gas exchange in air tracheae are air tubes that ramify thru body of insects (Fig 42.22) muscle contraction when moving pumps air in and out of tracheae lungs are found in most terrestrial vertebrates like gills, the lungs extract oxygen and distributed in circulatory system like tracheae lungs are internal and open to outside with narrow openings increasing metabolic rate demands different adaptations of lungs in amphibians, mammals, birds increase surface area for gas exchange amphibian have simple vascular sac-exothermic mammals and birds more active and require greater surface area mammals have alveoli-blind vascular sacs that increase surface area for exchange. For example: humans have 100m2 for gas exchange (300m2 in intestine) birds have parabronchi Fig 42.25 Ventilation of lung amphibian lung sac filled by positive pressure (air pushed into lung from mouth cavity) mammals contract diaphram and some muscles in rib cage to expand thoracic cavity, creating negative pressure, and drawing in air. Relax and thoracic cavity gets smaller and air pushed out. Negative pressure breathing birds use system of air sacs to force air in one-way flow over lungs. Countercurrent flow of air and blood supply. Why do birds need such efficient lungs? High metabolism and fly at high altitudes where air pressure low with concomitant decrease in partial pressure of oxygen. Controlling the internal environment temperature, osmolarity (total solute concentration) Exchange between the organism and outside environment is constantly occurring Some small aquatic organisms may experience osmosis across outer body wall—whether they swell up or shrivel up depends on the solute concentration of their environment and internal fluids. terrestrials have waterproofed coverings, but still exchange water: loss while breathing, sweating, urinating, gain by drinking, eating conformers vs regulators Fig 44.1 Osmoconformers do not actively adjust internal osmolarity (total solute concentration). This group cannot include terrestrials or freshwater animals, but some marine animals have same osmolarity as surrounding water, thus they don’t swell or shrink animals first evolve in sea—most invertebrates remain as marine osmoconformers; hagfish, primitive vertebrates, are osmoconformers Osmoregulators maintain different internal osmolarity than external environment, and to prevent swelling or shrinking, must expend energy to move water out or in. marine environments sharks maintain lower salt concentration, but are still hypertonic to sea water because they have urea in cells- take in water that must be excreted through urine formed in kidneys bony fish are hypotonic (evolved in fresh-water) and thus lose water, and must drink water and excrete excess salt (Fig 44.14a) fresh water take in water (hypertonic to environment) and must excrete excess water (Fig 44,14b) terrestrial minimize water loss to dry environment (fig 44.16) maintain constant internal environment by conserving water Transport epithelia regulate water movement sheet of cells in contact with external environment (adaptations to increase the surface area). These cells contain transport proteins in membrane that control movement of solutes across epithelia--water follows In insects, malphigian tubules contain transport epithelia bathed in hemolymph (Fig 44.20). Active transport across epithelia regulates waste excretion and water balance. What fuels active transport? In earthworms, with closed circulatory system, the transport epithelia are closely associated with blood supply. In vertebrates, kidneys are compact but packed with tubules containing transport epithelia kidney parts (fig 44.21) cortex medulla pelvis nephron: long tubule + glomerulus with Bowman’s capsule juxtamedullary nephron with long Loops of Henle Important in water retention, know based on finding that desert animals have very long loops of henle, Fish, amphibians and reptiles do not have loops of henle birds have only short loops mammals have long and short loops; kangaroo rats have only long, mountain beaver only short, human 14% long glomerulus is supplied with blood; pressure forces plasma and small solute out and into bowmans capsule and into tubule filtration is non-selective; followed by secretion and reabsorption of specific molecules—artificial kidneys can only filter non-selectively changing permeability throughout length of loop of henle sets up countercurrent flow with increasing concentration of solutes (salt and urea) toward medulla long loop of henle allows lots of water to diffuse out of the tubule ability to concentrate urine is key terrestrial adaptation, but the system responds to feedback. Antidiuretic hormone (ADH) is discharged in response to increases in blood osmolarity permeability of collecting duct to water increases and more water is pulled out of tubule ADH is reduced when blood osmolarity is lowered (i.e., after drinking a lot of water) permeability of collecting duct to water decreases and more water passes out in urine ADH is produced in hypothalmus and released by pituitary gland alcohol and caffine inhibit release of ADH kidney is the organ for osmoregulation and nitrogenous waste excretion nitrogen (ammonia) is removed from proteins and nucleic acids when they are broken down for energy or converted to carbohydrates or fats ammonia is toxic and soluble in water and most aquatic animals excrete ammonia in fish ammonia diffuses across gills into water, with little nitrogenous waste excretion carried on by kidney (osmoregulation only) urea is less toxic than ammonia and is used by terrestrial organisms because it can be accumulated and excreted using a minimum of water uric acid is insoluble is water and thought to be necessary in organisms that produce shelled eggs: birds and reptiles—soluble wastes would contaminate the egg Thermoregulation heat is exchanged btw organism and environments heat is radiated from animals; heat can be absorbed from environment just as with osmoregulation, animal must regulate heat ectotherms and endotherms have different ways of maintaining temperature ectotherms = invertebrates, fish, amphibians, reptiles not cold-blooded, temp necessary for metabolism, muscle movement ectotherms derive most heat from environment have few adaptations for retaining heat behavioral adaptations regulate heat benefits energy not used for temp regulation; i.e., eat less costs activity limited when temp low endotherms, mammals and birds, and some insects and fish temp maintained through metabolism of animal generating heat requires energy, i.e., food adaptations for retaining heat feathers and hair countercurrent heat exchangers adaptations for releasing heat evaporative cooling adjusting flow of blood to skin surface Negative feedback controls body temperature. decrease in body temp sensed by nerve cells and hypothalmus start shivering constrict blood flow to skin increase body temp start sweating open blood flow to skin Nervous Systems Communication within body occurs exclusively by chemical signals (hormones) in plants, but animals have both chemical signals and electrical signals and the two systems are intertwined nervous system at simplest level provides: sensory input, integration, motor output (fig 48.1) sensory input and motor output accomplished by neurons of peripheral nervous system (PNS) integration accomplished by neurons of central nervous system (CNS) neurons specialized cells for transmitting signals throughout body (fig.48.2) cell body with nucleus an other organelles dendrites convey signals from tips toward cell body axons convey signals from cell body to tips Schwann cells form myelin sheath covering axons in the PNS of many vertebrates; in CNS glial cells form myelin sheaths (fig 48.5) function to insulate the electrical impulses that move down the axon; connect to other neurons at synaptic terminals sensory, motor and integration neurons how do nerves transmit signals? early work done on large neurons from squids knew muscle cells could be stimulated to contract with electrical signals at first thought they conducted electrical signals just like electric wire by inserting microelectrodes into axon, discovered that inside of the cell was more negatively charged than outside (-70mV) (fig 48.6) if electrodes inserted along axon, and nerve stimulated, first one electrode would record a spike of positive charge inside the axon and a fraction of a second later, the second in line would record a spike of positive charge the degree of change in electrical potential in the cell did not respond to changes in stimulation of nerve, but did impact the frequency—the nerve impulse was an all-or-nothing response action potentials are electrical signals that flow down axon resting potential is term applied to non-stimulated neuron (most cells only occur in this state) normally cells more negative inside than outside—why? (fig 48.7) inside: neg ions--proteins, amino acids, phosphate are rarer outside the cell; pos ions--K outside: pos ions Na, some K membrane potential is -50 to -100 mV = resting potential ions can’t move thru phosolipid bilayer, thus need transport proteins or ion channels (proteins too) K and Na diffuse thru ion channels passively and eventually gradient would dissipate—Na-K active pump works in opposition to diffusion all cells have membrane potential, only neurons and muscle cells (excitable cells) adapted to change membrane potential neurons have gated ion channels that allow nerve to change permeability to different ions See Fig. 48.9 nerve stimulation opens ion channel for Na+, which rushes into cell because of: 1. concentration gradient; [Na+] low inside cell 2. electrical attraction; Na+ attracted into negatively charged cell interior nerve stimulation also opens, but more slowly, ion channels for K+, which rush out of cell because: 1. [K+ ] low inside cell 2. electrical replusion from the influx of positive charge (Na+) into the cell a stimulus will open Na channels; if only a few channels open, the interior of the cell becomes slightly more positive, but if it reaches about -50mV, then it sets of action potential; see fig 48.8 action potential in one part of axon stimulates the adjacent region to depolarize too (see fig 48.10) Transmission speed varies depends on diameter of axon (larger = faster); in invertebrates large axons important in speeding transmission rates (i.e., in thin axons 3m/s to 100m/s in giant axons) depends on myelin sheaths in vertebrates; saltatory conduction of impulse neurons are joined together by synapses (fig 48.12) most synapses use a chemical messenger to carry signal across a synaptic cleft chemical messenger = neurotransmitter which is released from vesicles of the presynaptic neuron neurotransmitter diffuses across cleft and stimulates the postsynaptic neuron to fire many neurons (i.e., sensory neurons) synapse with a single postsynaptic neuron. firing by postsynaptic neuron depends on summation of stimuli received by the neuron some neurons act in an inhibitory manner some neurons act in an excitatory manner several excitatory synapses releasing neurotransmitters at the same time or nearly so required to stimulate postsynaptic nerve to fire omit details variety of types of neurotransmitters table 48.1 indicates that many are familiar names serotonin thought linked to mood, and sleep cycles endorphins organization of nervous systems varies with different animal groups simple invertebrates with nerve net, without central control, brain, or division into CNS and PNS bilaterally symmetrical animals have CNS; i.e., planaria have small brain and nerve cord (bundles of neurons) evolutionary trends in vertebrates brain size increases relative to body size in mammals and birds fish, amphibians and reptiles show similar ratios of brain size to body size as size increases, so does compartmentalization forebrain with the cerebrum especially increases in some mammals, especially humans. cell bodies of the neurons in the cerebrum are gray matter and located in the cerebral cortex; these neurons integrated complex behaviors and learning, thus “smarter” mammals have more surface area in their cerebral cortex Sensory Systems what are perceptions? things like: colors, sight, sound, smells perceptions based on matter and energy that can stimulate nerve cells Sensory receptors transduce stimulus energy energy stimulates a change in membrane permeability Sensory receptors classified by type of energy they transduce mechanoreceptors stretching of membrane results in depolarization pain receptors thermoreceptors chemoreceptors electromagnetic receptors (light, electricity, magnetism) Reproduction Asexual produces offspring without meiosis fission-protista, invertebrates (anenome, planaria) budding-hydra fragmentation and regeneration-cnidarians, some annelids, planaria limited to simple body plans; common in plants Sexual reproduction involves meiosis and usually the fusion of gametes most species have males and females with fusion of gametes occuring EITHER externally-aquatic; lots of eggs produced internally some species are parthenogenetic-egg develops without fertilization aphids, water fleas, adults from unfertilized eggs are haploid—why would a species reproduce this way? in wasps, bees, mites males develop from unferilized eggs—whats the effect of this? female/male ratio is high in vertebrates unfertilized eggs double their chromosome number to produce diploid copies of mother tradeoff between asexual vs sexual reproduction hermaphrodites produce eggs and sperm i.e., earthworms sequential hermaphrodites sex can be determined by environmental cues