Biology Final I. Circulation 1) Anatomy/ Circuits 2) Human circulatory system 3) Control of heart beat 4) Lymph system II. Blood Plasma Cellular components III. Immunity Circulatory Systems Fig 42-8 Circuits -open system-blood is also in body cavity of vessels, heart pumps blood into vessels that have open ends -closed system- blood within vessels( more efficient/ blood flows through a continuous circuit of blood vessels Vertebrate Blood Vessels -artery: carries blood away from a heart chamber, towards other tissues -when an artery enters an organ, it divides into many arterioles -veins: channel blood back toward the heart Fish Circuit: fish heart has one atrium and one ventricle. Atrium pumps blood into ventricle blood is oxygenated as it passes through capillaries in gills. After blood circulates through gills, its pressure is low(Blood passes very slowly to other organs/ blood returns to heart w/ low oxygen content --when its deoxygenated, goes to gills to get oxygen(gets blood to gills pretty quickly to oxygen(when you get oxygenated blood( it is in low pressure from gills to body -in amphibians- wall between ventricles in heart doesn?t exist 2) Human Circulatory System -closed system -Arteries-lead blood away from heart, large arteries near heart -arterioles are smaller arteries farther away from heart -Veins-get blood to heart -lymph system- moves fluid through body -lymph system connect to circulatory system through blood Arteries(arterioles( capillary beds( veins( veinals( heart Blood vessels: - 3 tissue layers (tunica) Tunica intima(closest to blood Tunica media( smooth muscle- controls diameter of tube Tunica adventida( outer layer, connective tissue (toughest tissue) which helps suspend to other connective tissue -one way veins- only move towards the heart -by having smooth muscle and arterioles they have control of which muscle the blood should go -arteries maintain their shape, while veins don?t Capilaries: just tunica intima, thin membrane Human heart: 3) Control of Vertebrate Heart Beat- influence heart beat by brain -autorhymtic- there is no nervous system input?built in leak system, automatically starts cardiac muscle contraction( pacemaker for heart -at their ends cardiac muscle cells are joined by dense bands called intercalated discs- sites where a synapse is/ each disc is a gap junction -intrinsic conduction system( needs to be coordinated (conducts depolarization, distributes it throughout/ offers very little resistance to the passage of an action potential, ions move easily through gap junctions, allows muscle mass to contract -each beat is initiated by the pacemaker, or the Sinoatrial node- cardiac muscle located near the superior vena cava( ends of SA node fuse w/ surrounding atrial muscle so action potential spreads through atria( produces contraction Rest of System: -atrioventricular node-the transmission is delayed briefly, lets the atria finish contracting before ventricles begin to contract -AV Bundles- from the AV node the action potential spreads into Purkinje fibers, which make up the AV bundles, called the bundle of his SA node(atrial muscle fibers (atria contract) ( AV node( AV bundle (purkinje fibers)( right and left branches (Purkinje fibers)( ventricular muscle fibers (ventricles contract) -contraction starts from bottom and then goes up -artial depolarization- P wave -QRS complex-ventricular depolarization -T wave- ventricular repolarization 4) lymph system- collects interstitial fluid to the blood; launches immune responses to defend body against diseases; and absorb lipids from digestive tract -lymphs join the circulatory system at base of subclavian veins by : thoractic duct- left side and right lymphatic duct- right side a) Anatomy -lymph-clear watery fluid formed form interstitial fluid -capillaries and veins -lymph nodes- lymph tissue is organized into small masses of tissue called lymph nodes Lymph system organs -thymus -spleen -tonsils-masses of lymph tissue under the lining of the oral cavity and throat -Peyer?s patches- hangouts for immune system B. Blood Pressure BP= Blood Flow x Peripheral resistance Blood flow Blood volume (salt_ -cardiac output (stress) -see figure 42-12 pg 820 -salt goes in( becomes hypertonic solution( water goes in Starling?s Law of the Heart pg 820 -volume of blood one ventricle pumps during one beat is the stroke volume Starling?s law of the heart- if the veins deliver more blood to the heart, the heart pumps more blood( when extra amts of blood fill heart, the cardiac muscle fibers stretch more and contract w/ greater force, pumping a larger volume of blood into arteries Blood pressure- force exerted by the blood against the inner walls of the blood vessels/ blood pushing against the walls of the vascular system. Determined by cardiac output, blood volume, and resistance to blood flow Blood flow -blood volume (salt) -cardiac output (stress) Peripheral resistance- resistance to blood flow caused by blood viscosity and by friction between blood and the blood vessel wall -blood viscosity- doesn?t vary very much/ constant Ex. leukemia changes viscosity -the friction betweens blood and blood vessel wall is more important/ change in diameter can result in a big change in blood pressure **vasoconstriction- smooth muscle constricts and makes diameter smaller Vasodilation- smooth muscle dialates and diameter is larger, when a tissue is metabolizing rapidly and needs more nutrients and oxygen -friction is giving you peripheral resistance -if you constrict it, has more turbulent flow -in arterioles, lose a lot of blood pressure, arterioles have more surface area, more peripheral muscle 1) Peripheral resistance: greatest in arterioles, can control arteriole diameter (vasoconstriction) Pg. 821 42-14b Systolic-120- heart when contracting Diastolic-80- heart when at rest -decline in blood pressure in arterioles -capilaries- 30-40 in pressure / when it gets high blood pressure( capillaries break In kidney, capillary bed?fluid goes from blood to urine( in high blood pressure, it breaks and blood is released into the urine -blood pressure is 0 by the time we?re at the veins Atherosclerosis- disease where arteries are damaged, inflamed, and narrow as a result of lipid deposits in their walls/ hardening process -building of cholesterol on lining of arteries/ as diameter decreases, more turbulence Artersclerosis- calcium deposited -stiffens entire vessel-lose elasticity -plaque stays because of hardening/ more turbulent flow?will easily tear -more cholesterol-more rip and tear/ the more rip and tear( the more cholesterol Obesity- increase in peripheral resistance -adipose tissue-have more blood vessels- more peripheral resistance- heart pumps harder- increases blood vessel 2) How does blood get back to heart? Starling?s Law of the hear: use fig 42-20 pg 827 --osmotic pressure --when blood enters a capillary network, it is under high pressure(plasma is forced out of the capillaries and into the tissues -once it leaves the cells, the fluid is called interstitial fluid --the main force pushing plasma out of the blood is hydrostatic pressure, which is the blood pressure against the capillary wall. The osmotic pressure of interstitial fluid adds to filtration pressure. However, the principal opposing force is osmotic pressure of the blood which restrains fluid loss. --at venous ends, the blood pressure is much lower, the osmotic pressure of the blood draws fluid back into the capillary, but not as much fluid is absorbed back into the circulation as is filtered out -98% of water put out is put back in -how do we get 2% of water that is not put back in the capillaries??put in the lymph system ii) Breathing?negative pressure in thoracic cavity iii) Skeletal muscle action?as you move around, get blood from veins to heart -contraction of skeletal muscles helps move blood through the veins II. Blood Hematocrit- take and put it in tube( heavy things go to bottom 45% cells 55% liquid 1)Plasma -92% water -7% protein -1% salts and minerals -plasma is in dynamic equilibrium with the interstitial fluid bathing the cells and with the intracellular fluid -plasma contains several kinds of proteins: albumins, fibrinogen, and globulin Globulin-lipoprotein Fibrinogen- involved in the clotting process Albumins-stay in the blood plasma --how we can modify blood volume by adding albumin( making blood hypertonic -increase blood volume- pump albumin -helps regulate distribution of fluid between plasma and interstitial fluid 2) cellular components a) Red blood cells, or erythrocytes, are highly specialized for transporting oxygen/ contain hemoglobin, move oxygen around by binding to hemoglobin hemoglobin- O2 binds to hemoglobin -has a high ratio of surface area to volume- allows efficient diffusion of oxygen and carbon dioxide into and out of the cell -erthrocytes are produced within the red bone marrow of certain bones --multipotent cells of bone marrow are constantly being made because they don?t have nucleus -if O2 levels are low: -amount of erythocytes are controlled by the kidneys -red blood cell production is regulated by the hormone erythropoietin?which the kidneys release in response to a decrease in oxygen( becomes a negative feedback/ too much erythropoietin declines the red blood cell differentiation -life span of a human red blood cell is about 120 days(as blood circulates through the liver and spleen, phagocytic cells remove worn out RBC?s from the circulation and some of their components are recycled b) Leucocytes (WBC): specialized to defend the body against harmful bacteria and other microorganisms-also from multipotent cells --granular leukocytes-large, lobed nuclei and distinctive granules in their cytoplasm 3 varieties of granular leukocytes are the neutrophils, eosinophils, and basophils Neutrophils-principal phagocytic cells in blood Eosinophils-large granules, contain enzymes such as oxidases and peroxidases? detoxify foreign proteins Basophils-play a role in allergic reactions?contains histamine Agranular leuikocytes?lack large granules and nuclei are rounded Lymphocytes?produce antibodies Monocytes-becomes macrophage-giant scavenger cell c)Thromocytes- in mammals thrombocytes are tiny spherical or disc-shaped bits of cytoplasm that lack nuclei-called platelets -platelets are pinched off from very large cells in the bone marrow (megakaryocytes) -when a blood vessel is cut, it constricts(reduces blood loss -platelets stick to the rough, cut edges of the vessel, physically patching the break/ as platelets begin to gather, they release substances that attract other platelets( form a platelet plug or a temporary clot --as the temporary clot forms, a stronger permanent clot begins to develop Immunity Pathogens-disease causing organisms(includes certain viruses, bacteria, fungi Nonspecific immune response (innate immunity)- provide general protection against pathogens/ prevent most pathogens of entering the body Specific (Adaptive)- highly specific, can?t do multiple infections, go specifically against one pathogen Antigen-any molecule that cells of the immune system specifically recognize as foreign -antibodies are highly specific proteins that recognize and bind to specific antigens A. Danger Model- How do you know what stuff stays and what stuff goes out? -has to do with shapes of proteins on cell membranes -self vs. non self- an animal?s immune system recognizes its own cells and can identify those of other organisms as foreign---when a pathogen invades an animal, its distinctive macromolecules stimulate the animal?s defensive responses -dange model hypothesizes that the immune system responds to danger signals from injured tissues, such as proteins released when cell membranes are damaged PAMPs (pathogen-associated molecular patterns)- some common molecular features of classes of pathogens (what viruses make and the body doesn?t make) Major histocompatibility complex (MHC)- genes which makes the vertebrate immune system distinguish between self from nonself -in humans the MHC is called the HLA (human leukocyte antigen) complex MHC genes encode MHC antigens, or self-antigens that differ in chemical structure Class I MHC proteins: -found in essentially all cells, encode glycoproteins expressed on the surface of most nucleated cells -these antigens bind with foregihn antigens from viruses or other pathogens within the cell(forms a foreighn antigen-class I MHC glycoprotein complex/ cell displays this complex on its surface and presents it to Tc cells --if you get infected-bad guys get into you, protein gets piece of bad guy and sticks it on the protein -body gets rid of protein because it looks different I. Immunology A. Danger Model B. Defense Systems i. Non-specific ii. Specific a) antibody mediated b) cell mediated II. Orgasmic Respriation The problems Systems for Gas Exchange 1)Body Surface 2) Respiration Systems a) Characteristics b) Mammalian system Major Histocompatibility Complex -glycoproteins in cell membrane -when we get infectious(stick classI out there( becomes a marker Class II MHC proteins -encode glycoproteins expressed primarily on ?professional? APCs?dendritic cells, marcrophages, and B cells -the MHC antigens combine with foreign antigens from bacteria and the cell presents complex to Helper T cells -will react to inappropriate cell markers -if it doesn?t belong( it becomes phagotocytes ( sticks it on Class II proteins -conquer something and show it off, now becomes active and excited -display Class II histomology proteins B. Defense systems -use Fig 43-4, pg 837 Fig 43-1 pg. 833 1) Non-specific Defenses (Innate Immunity)- non specific defenses Physical barriers- eyes, eyelashes, earwax, mucus Soluble molecules (cytokines, complement) Cytokines- large group of proteins that serve as signals and perform regulatory functions during both nonspecific and specific immune responses/ cause agents to make immune system active Interfereons- a type of cytokines which are produced when infected by parasites or other intracellular parasites/ inhibit viral replication and activate natural killer cells that have antiviral actions -cytokines produced by phagocytes can activate the complement system Complement- activated when an antigen has antibody bound to it or the presence of certain pathogens/ lyse viruses, coat pathogens to make them less slippery, release white blood cells c) Phagocytosis -neutrophils -monocytes-cells will become activated and phagocytize the substances Marcrophages (APC) Dendritic cells (APC) -Neutrophils- non specific, most common white blood cells, major phagocytes- phagocytize about 20 bacteria before it becomes inactivated Ex. puss is neutrophils(accumulation of dead neutrophils -monocytes-white blood cell-produced and liberated from bone marrow Dendritic cells- lots of extensions, goes into linings of the body, linings of digestive, respiratory, urinary and vaginal passageways/ when pathogens infect a tissue, dendritic cells are activated by PAMPs and capture the pathogens, also are specialized to process, transport, and present antigens to T cells(look for things going into skin(phagocyte to Class II proteins -macrophages-large phagocytes develop from white blood cells, phagocytize about 100 bacteria d. Inflammatory Response(protective response)- begins immediately after pathogen invasion or physical injury -tissue injury activates a clotting factor in the blood plasma -reactions generate molecules, like the peptide bradykinin- mediate the inflammatory process, dilate blood vessels and increase capillary permeability -large numbers of neutrophils migrate to inflamed tissue and secrete cytokines -mast cells stationed in the tissue respond by releasing histamine in nasal cavity -mast cells and macropages release signaliing m olecules that attract and activate additional neutrophils -interleukins reset the body?s thermostat in the hypothalamus, results in fever e. Natural Killer cells- large, granular lymphocytes that originate in the bone marrow -attack membranes -look for things that doesn?t have Class I proteins -immune system ignores the cells without Class I protein -NK cells release cytokines, as well as perforins and granzymes Perforins- cause pores to form in the plasma membrane of target cells(allows granzymes to enter the cells Granzymes- activate a cascade of reatctions that cause the cell to self destruct by apoptosis --active against tumor cells and cancer(infeced cells lacking MHC I proteins 2) Specific Defenses (adaptive or acquired immunity) --acquire defense mechanim once we get infected-method of saving energy T lymphocytes-body?s cellular soldiers, travel to site of infection and attack body cells infected by invading pathogens/ mature in thymus gland, move out to lymph system B lymphocytes- mature in bone marrow and move to lymph nodes, mature into plamsa cells, which produce antibodies Helper T Cells -respond to antigens presented by APCs (antigen presenting cells) -in order to have specific reaction develop, have to have helper T- cells -the Class II proteins are looking for helper T cells -also known as CD4 cells- class II protein has to match receptor on helper T cells -matches shape of antigen -problem with HIV-destroys Helper T cells Fig 43-5 pg. 839 Helper T cell activation-helper T cell goes through clonal proliferation-makes a lot of copies -store some extra versions of helper T cells as memory T cells( protects us for a long time 1. Antibody mediated B lymphocytes will eventually grow to antibodies B lymphocytes also have toll like receptors and phagocytze cells -helper T cells looking for B lymphocytes to match -Helper T cells find the B lymphocyes with the antigen presented in Class II -Helper T cell dependen-most of our body does that -the B cell does clonal proliferation -after clonal proliferation, plasma cells make antibody/ plasma cells pump out antibodies(which match the shape of the antigen -Pathogen invades body(APC phagocytizes pathogen(preign antigen-MHC complex displayed on APC surface( Helper T cell binds with foreign antigen-MHC complex, when activated Helper T cells undergoes clonal proliferation, a lot of Helper T cells( activated Helper T cell interacts with a B cell that displays the same antigen(B cell is activated( clone of B cells(B cells differentiate, becoming plasma cells( plasma cells secrete antibodies(antibodies form complexes with pathogen( destroy pathogen Constant portion-all the antibodies are the same shape/ animo acid sequence is constant within a particular immunoglobulin class Variable portion- the part that has varying shapes of antibodies, unique amino acid sequence -antibodies-are markers and activators of our immune system -typical antibody is a Y shaped molecule in which the two arms of the Y bind with the antigen. This shape enables the antibody to combine with two antigen molecules and allows the formation of antigen-antibody complex Antibody effects: -precipitation- when antibodies bind( soluble things are precipitated out -agglutimation- it is in clumps, cut down the spread of antigen(more easier for the phagocytes to phagotize the antigen(slowing it down/ stimulates phagocytic cells to ingest the pathogen -activates complement protein-complement what the antibodies do(have more antibodies and good guys/ when antibodies combine with a specific antigen on a pathogen, complement proteins destroy the pathogen -complement cells increase phagocytosis like antibodies Memory cells- why we are safe later on -2nd time you get disease- quick response and produces a lot of antibodies rapidly -defense that is specific for agens that have gotten into the cell 2) Cell mediated -T lymphocytes -cytoxic T cells (Tc Cells) -also known as CD8 cells-receptors have to match the shape of antigen -has cytotoxic T cell that matches shape of Class I protein Tc Cells- activated by: antigen-MHC I complex and cytokines -results in: clonal proliferation -attack the new agents if they have a different antigen- Class I protein -when a virus infects a cell, some of viral protein is broken down and displayed w/ class I MHC molecules( T cells have same antigen specificity and once activated they respond by making clones. Tc cells make way to infected area and destroy target cells. Tc cells secrete perforins and granyzmes and kill it by apoptosis. Fig 43-5 pg. 835 Increase in antibodies in a week -primary response- first exposure to an antigen -secondary response- second exposure to antigen, more rapid than primary immune response Natural Acquired Active Immunity -natural-went through primary response and secondary response -acquire illness naturally Artificially Acquired Active Immunity -get it through a needle or pill -allows it to go through primary response so in nature, it will undergo a secondary response Passive immunity-physicians inject people with antibodies actively produced by another organism Naturally Passive immunity didn?t go to clonal proliferation, no helper T cells( you naturally get antibodies from breast feeding Artificially Acquired Passive Immunity -you get a injection of gamma globulin -after a period of time( antibodies break down -immunity only lasts as long as the antibody is in you Orgasmic Respiration- oxygen from the environment is taken up by the animal and delivered to its individual cells The problem Systems for Gas Exchange Body Surgace A. The Problem -gas exchange -obtain 02 -dispose of CO2 -carbon dioxide comes out of Kreb?s cycle -have to get rid of CO2 -CO2 brings down the blood pH -C02 increases, blood pH decreases a)Mechanism of exchange -always diffusion -from high partial pressure to lower partial pressure -no ATP used -higher partial pressure- more gas Earth?s atmosphere: 21% Oxygen 21% x 760 mm Hg= 160mm Hg/ p O2 -160 mm Hg is partial pressure of atmospheric O2 pCO2=.3mm Hg -partial pressure higher in blood( will diffuse out into air -the concentration of oxygen in the cells is lower than in the capillaries entering the tissues, and concentration of carbon dioxide is higher in the cells than in the capillaries--? Oxygen moves by simple diffusion from blood to the cells Dalton?s Law of Partial Pressure- in a mixture of gases, the total pressure of the mixture is the sum of the pressures of the individual gases Air into alveoli O2=160 mm Hg CO2= .23 mm Hg Blood into alveoli 02=40 mm Hg CO2= 45 mm Hg Blood into capillary 02=100 mm Hg CO2= 40 mm Hg Tissue around capillary 02= less than 40 mm Hg CO2= Greater than 45 mm Hg -oxygen molecules efficiently pass by simple diffusion from the alveoli, where they are more concentrated, into the blood in pulmonary capillaries, where they are less concentrated -at the same time, carbon dioxide moves from the blood to the alveoli, where it is less concentrated -inhales air contains about 20.9% oxygen, but exhaled air contains only 14% oxygen. -each gas exerts a partial pressure- the same pressure it would exert if it were present alone At equilibrium: Partial pressure in air= partial pressure in water -organisms in water( 02 is a limiting water -the warmer thewater, the less gas in there Fick?s Law of Diffusion -the amount of oxygen or carbon dioxide that diffuses across the membrane of an alveolus depends on the differences in partial pressure on the two sides of the membrane and the surface area of the membrane -gas diffuses faster if the difference in pressure or the surface area increases B. Systems for Gas Exchange 1) Organism Surface i. If thinner than 1 mm: ex. platyhelminthes -don?t need respiratory system(relies on diffusion of gas exchange -gases diffuse easily through pseudocoelom -body can get larger without respiratory or circulatory system ii. If thicker than 1 mm: -circulatory system -respiratory system-by skin diffusion/ -earthworm doesn?t have one 2) Respiratory systems A. Characteristics 1) Thin walled- distance gas has to diffuse is very thin 2) Moist- moist coding 3) Richly vascularized -maximum partial pressure A breath of air enters the body through the nostrils and flows through the nasal cavities Beneath nostril( nasal cavity -conhae-increase surface coded with mucus(humidifies air -ciliated epithelium -Bernoulli effect-changes diameter( small opening to a larger opening, slows down air -as air slows down(blood slows down, blood gets stuck in mucus The back of nasal cavities is continuous w/ throat region or pharynx An opening in pharynx leads to larynx. From the larynx, air passes into the trachea. Trachea divides into two brances, the bronchi(connects to lungs Bronchioles/ asthma is problem in bronchioles( smooth muscle contricts-difficult to get air to conducting zone Alveoli located at the end of bronchioles( gases actually exchange( a lot of surface area/ emphysema- destruction of individual alveolus Figure 44-7, pg. 864 -alveoli are very delicate -surface tension would cause them to collapse -pulmonary surfactant breaks surface tension of water -one end is polar, other end is non polar -the work of breathing is reduced by pulmonary surfactant, a detergent-like phospholipids mixture secreted by specialized epithelial cells in the lining of the alveoli -pulmonary surfactant reduces the surface tension of the water, prevents the alveoli from collapsing -when pulmonary surfactant levels are low( respiratory distress syndrome 3) Ventilation a) Positive pressure- frogs -we use negative pressure, diaphragm goes down b) Negative pressure -Inspiration-contract downs, diaphragm moves downward -Expiration-contract up, diaphragm relaxes -intercostal muscles- when large volume of air is inhaled, these muscles contract and moves the ribs upward, and increases volume of thoracic cavity Excretion I. Excretion A. Homeostatic Functions B. Nitrogenous Wastes C. Human System Homeostatic Functions -?same position? -the automatic tendency of an organism to maintain a steady state 1)Osmoregulation -regulating water and salts -need to maintain osmotic balance 2) Excretion of metabolic wastes Fig 46-6 pg. 901 -urine carries waste products -lungs and skin( how we get rid of metabolic waste products Nitrogenous wastes -our metabolism of proteins- amino acids -protein breakdown -metabolism of amino acids( gets rid of amino group (NH3)( deamination -converted to ammonia NH3 -can do 3 things -leave it as ammonia- a lot of water, No ATP -convert to urea, moderate ATP and water -convert to uric acid- a lot of ATP, no water 1) If aquatic animal: excrete ammonia 2) Insects, Birds, some reptiles: Ammonia(uric acids (more energy, less water) -don?t want water because its heavy( they need to fly 3) mammalian, most amphibians Ammonia( urea -urea?by the liver( goes to kidney(goes to the blood C. Human Urinary System Kidney(uterer( bladder (storage)( urethra -as urine is produced, it flows into uterer, ducts that connect the kidney with urinary bladder. Bladder holds urine. During urination, urine is released from the bladder and flows through the urethra -heavy blood flow( kidneys 1)Kidney?pg 902 Fig 46-8a -outer layer- cortex -inner layer-medulla -renal elvis-all nephrons connected -work of kidney done by specialized tubules called nephrons -corticol nephron- in cortex- relatively small glomeruli/ located within the cortex -as fluid moves through(produces urine i. Glomerulus/ Bowman?s Capsule pg. 903 46-9b -glomurulus-tuft of capillaries 2 parts of renal -fluid goes out to Bowman?s capsule through nephron- 3 processes 1)Filtration- plasma of blood goes out to Bowmen?s capsule(filtrates 2) Reabsorption- keeps materials in capillaries 3) Secretion-gets rid of dye, extra things you have to get rid of I. EVOLUTION (lectures 21-25) -accumulation of inherited changes in populations over time II. Ecology (lectures 26-28) -natural selection -25,000(vertebrates -250,000 flowers -over million arthropods -30 billion species over course of time 99.99% are extinct Theory of Extraterrestrial- brought from outer space Creationism-supernatural being produced every organism, belief, everything is immutable( does not change 1619( man came from apes Darwinian evolution- organisms change over time -every living organism is related, some are closely related Darwin- greatest contribution- discovered the mechanism of evolution -other scientists couldn?t explain it before Malthus-economist- realized resources were finite Lyell-geologist, believed Earth was billions of years old, Earth was changing, evidence was erosion and volcanoes -Lamarck-believed in evolution-believed traits were acquired(WRONG/ -used example of why giraffes have long necks -giraffes kepts stretching neck for leaves higher up on tree(neck became progressively longer( long necked descendant after many generations What really happens: Giraffes with short necks eventually unable to get vegetation and die/ Longer neck giraffes survive and pass on their characteristic -survival of the fittest -individuals born with traits that make them best adapted for their environment are also the ones most likely to survive and produce offspring -those who survive will produce offspring -idea of natural selections Darwin?s Arguments for Natural Selection Overproduction- all organisms produce more offspring than they?re going to survive Resources are finite(one population reaches a certain point?population decreases Variation- individuals within species vary (some are more ?fit? than others Variation is the raw material for evolution/ natural selection enchances variation Differential reproductive success- those who survive will reproduce offspring Overproduction -with unlimited resources(population will have exponential growth Resources are finite -at environmental resistance, the population increase is slower(start to stabilize Variation -individuals within species vary -raw material of evolution -Natural selection acts on variation Differential reproductive success -many few organisms make it to adulthood -mating is not random(survival of the fittest -most fit individuals produce the most offspring Evidence 1) Artificial selection- choosing certain traits and breeding only individuals that exhibited the desire traits -man doing the selection process, especially in plants -analagous to natural selection -increased egg production -natural selection- wolf is the origin of all dogs 2) Fossil Record -evidence of evolution -don?t have good fossils in the tropics Ex. Horse evolution can be traced with fossils?horses are bigger -fossil record shows a progression from the earliest unicellular organisms to the many unicellular and multicellular organisms living today -fossils of different geological ages, the evolutionary relationships that gave rise to modern day organisms can sometimes be inferred 3) Comparitive anatomy- of related speces demonstrates similarities in their structures -divergent evolution- branching off, homologus structures -Homoplastic features-structurally similar features that are not homologous but have similar features Homolgous structures -bird- wing/ lizard-leg/ human-arm( all came from common ancestor -homologous structures are evidence for divergent evolution -Homoplastic structures- similar in form and function but not in evolutionary origin/ ex. fly wings vs. bird wings ( convergent evolution Convergent evolution- independent evolution of similar structures in distantly related organisms Parent species Parent species Exadaptations (vestigial structures)- whale pelvic bones, has no function but still there -blind cava fish- why are they blind-no purpose Exadaptations in human -abdomen -muscle in ears -appendics -goosebumps has function in birds because hair goes up/ but in humans we just get colder 4) Biogeography- species from main land over time came to island and settled there -Darwin studied the plants and animals of islands off western Africa and the Galapagos Islands -Darwin concluded that species from the neighboring continent migrated or were carried to the islands where they subsequently adapted to the new environment and evolved to new species 5) Developmental Biology -all embryos have pharyngeal gill slits( make prediction that all came from common ancestor 6) molecular- most powerful data -molecular evidence for evolution includes the universal genetic code and DNA -correlate how related they are( through DNA -spider monkey( 11% DNA difference to humans -chimpanzee( less than 2% DNA difference to humans/ - we are more related to chimpanzee 7) Imperfect adaptations- designed to walk in all fours -because we don?t(We get knee, back and heel problems -natural selection works with what?s available Evolution Today -nothing contradicts each other Microevolution- changing of allele frequencies -variation -rabbit population exploded, but after a virus appeared rabbit significantly killed rabbits and then population stabilized Scales of Evolution Macroevolution- long term, large- scale changes above the species level, accumulation of many alleles Misconceptions -?evolution is theory about origin of life?( FALSE, it is about what came after -Organisms are always getting better( FALSE -Organisms ?trying to adapt?- the genes aren?t trying(happening by natural selection -can test microevolution/ make prediction on macroevolution based upon microevolution The fundamental problem with Lamack?s idea of species formation via acquired traits is that he focused on individuals -Lyell proposed that Earth?s physical features were changing over time Population( all the individuals of the same species living in a particular area at the same time. Share a common gene pool Gene pool( sum of all alleles of all genes in a population Dominant or recessive allele/ allele is a type of gene, one of two or more alternative forms of a gene Population genetics- the study of genetic variability within a population and the forces that act on it -Allele frequency- proportion of a specific allele in a particular population -Frequency stable-same frequency between time periods( no evolution is occurring -if there is a change in allele frequency(there is genetic equilibrium Hardy Weinberg equation- -shows that if the population is large, the process of inheritance does not by itself cause changes in allele frequencies -says gene frequencies don?t change by themselves -describes an idealized population that is not evolving -under certain conditions, allele frequencies are in genetic equilibrium P2 + 2pq + q2 P is dominant A q is recessive a P2 ( homozygous 2pq( heterozygous q2 ( homozygous -can figure out frequency of homozygous dominant, heterozygous, and homozygous recessive Genetic equilibrium occurs if certain conditions are met DNA cannot mutate NO migration(no exhange of alleles with other population of different allele frequencies Large population size Random mating( has an equal chance of mating with any individual from the opposite sex No natural selection(if natural selection occurs, certain phenotypes are favored over others -if mating is non-random, there are different amounts of alleles 1) Mutation -ultimate source of all new variation -very rate -must occure in a gamete to be inherited SARS virus-example of mutation -mutation allowed SARS virus to have a second host, the humans -most mutations are harmful -natural selection- want to remove harmful mutations 2)Gene flow- migration of breeding individuals between populations causes a t of variation corresponding movement of alleles -increases the amount of genetic variability 3) Genetic drift -founder population will have different allele frequency than wild population(founder effect-allele frequencies in the newly founded population are quite different from those of the parent population --ex. there are a lot of types of sterlings in Europe, only some of the species were taken to U.S./ only those species will evolve in U.S Genetic bottleneck- genetic drift can occur in the small population of survivors(as population again increases in size, many allele frequencies may be quite different from those in the population preceding the decline 4) Non-Random Mating -cost of meiosis- only pass ½ of your genes down -cost of males -cost of courtship and mating -recombination occurs during miosis -sex is almos always non-random Inbreeding -increases chances of getting homozygous recessive Natal Dispersal -they leave after mating Natural selection- members of a population that are more successfully adapted to the environment are more likely to survive and reproduce Stabilizing Directional Disruptive Stabilizing -bell shaped curve -selects against phenotypic extremes -individuals with average phenotype are favored -ex. birds stabilize at 4 eggs -selecting for the average Directional selection -favors phenotype at one of the extremes of the normal distribution -unfit is being selected against -SHIFTS the population curve -ex. if greater size is advantageous in new environment, larger individuals will become increasingly common in the population -ex. cacti will start to make more spines to survive( curve shifts Disruptive selection -trend in several directions rather than just one - rare, selects against the average -isolates 2 separate populations -2 different populations Ex. only food available was wood boring insects and seeds/ finches w/ longer beaks survived b/c they can open cactus fruits/ and those with wider beaks survived because the could strip off tree bark to expose insects. Sexual Selection -male wants to mate and pass his genes down -more advantageous to pass genes down -tug of war between sexes -it is a struggle Differential Investment in Reproduction -females makes egg only at a certain time in life -eggs are precious(females put a lot of energy into her egg, eggs are limited -males don?t invest much -the more mating male does, the more it increases its fitness(the more offspring you make, the more of his gines will be passed on -males are discrimant, males want to mate as many times -females are selective, -males want to mate as many times as possible, but females are choosy -females choose most fit Mating Strategies 1)Intersexual Selection(one sex chooses a mate (female choice) 2) Intrasexual Selection(among members of one sex (male-male competition_ -females want to choose most fit male, want the males to have good genes 1) Intersexual selection Female requires: -gender variation in male trait -How do females recognize if male is fit? Ex. in a bird species, females recognize males that have a bright beak -Ex. in a bird species, the ones with larger vocal chords have better chance to mate with females Benefits of Female Choice: Direct benefits: male provides resources that enhance survival or fecundity Indirect benefits: Male more fit, so offspring more fit (Good Genes Hypothesis-males ?give? female good genes) Direct: if male brings prey size of more than 20 mm. female recognizes that and will mate/ if nuptial gift too small: female leaves before sperm transfer Indirect: Good Genes Hypothesis- females choice in absence of male investment Consequences of Female Choice -Sexual Dimorphism- consequence of males(the higher the chance that they might be more recognizable by predators -when males and females are similar, there will be a benefit to females because they will get parental care 2) Intrasexual selection- males often compete for breeding locations, access to females -two males going to fight for the female Elephant seals -establish harems(groups of females -intense battle among males, fights often fatal -less than 30% of males mate Giraffes- less fighting, about ½ males and ½ females, so there?s less at stake, fights rarely fatal Chimpanzees- males know females are promiscuous, no violence Male Strategies Infanticide Copulatory plugs Coercion Mate guarding Prolonged copulation SpermCompetition Infanticide- males kill young after taking over a pride to bring females into sexual receptivity/ females become receptive when male lion kills cubs Copulatory plugs- female genitalia obstructed after mating Coercion Homosexual rape- males insert copulatory plug to render competitors ?sterile? Heterosexual Rape- unfit males rape the females Mate guarding- male protects female from other males Prolonged copulation- (form of mate gurading or copulatory plug)- penis swells up in vagina( no other males can mate/ -common in dogs and insects Sperm competition- male takes his genitals and scrapes the other guy?s sperm in the famale?s vagina out Mating Systems Monogamy- one female and one male mate for life Polyandry- one female mates with many males Polygyny- one male mates with many females(most common Monogamy- females are scarce or social cooperation for parental care -parental care is advantageous(offspring is more fit when raised by both parent than raised by a widow Polyandry- ex. bee mates with a lot of males/ another ex. males survives in plant with toxin while females don?t, the more times the female mates w/ males the more immune she will be of the toxin Polygyny- the alpha male mates with females -female defense polygyny- females forage cooperatively, resources plentiful, malesfight to control female group/ benefit to females: less harassment and highly fit males -Resource defense polygyny- females tend to be solitary, males establish territory containing resource essential to females/ -males fight over territories and access to females/ benefit to female: access to resources -Lek Polygyny- assembly area without resources/ males display, females choose Default strategy because: source widely distributed (not defensible), females widely distributed, so females can?t be monopolized Bowerbirds and Led Polygyny -males make a temple -many males with their own little temple -males find anything that?s blue -females come and inspects pad -young female more impressed with the ?bling bling?- then the male performs a dance if he?s fit -mature female looks at the elaborated dance more/ unfit male would impress young female by adding even more ?bling bling? Gorilla -testes=small/ penis=small -Fidelity=high -female has high fidelity, won?t mate with other males -male gorilla is not in competition with other males Chimpanzee -testes=large-houses a lot of sperm -penis=intermediate -female has low fidelity -intense competition Humans -penis thicker -brings pleasure, increases pair bonding -also pleasures the female/ orgasm-like a vacuum(increases fertilization -large testes is driven by sperm competition and low female fidelity -if female mates with several males, natural selection favors males producing more sperm -Humans have a monogonous relationship because men and women are similar in morphology -sexual dimorphism-male and females are different, don?t have a monogamous relationship Microevolution- changes in allele frequencies Macroevolution-changes in many allele frequencies Morphological species concept- classifying plants and other organisms based on their structural differences -limitations- polymorphism- 2 moths are same species but they look completely different Biological Species Concept (Ernest Mayr)- species consists of one or more populations whose members interbreed in nature to produce fertile offspring and do not interbreed with, or reproductively isolated from- members of different species -species are populations that are reproductively isolated -no gene flow because they are 2 different species -one limitation with the biological species concept is that it applies only to sexually reporoducing organisms -in articial conditions, 2 different speices are mated to get a fertile, sterile offspring -species are populations that are reproductively isolated in nature and produce viable, fertile offspring How does a species stay a species -Reproductive isolating mechanisms prevent interbreeding between two different species whose ranges (areas where each lives) overlap Prezygotic Barriers-reproductive isolating mechanisms that prevent fertilization from taking place Behavioral isolation-female can recognize the male by the fitness and dance of male, stops when one member does not recognize or respond to the signals of the other/ if auditory signals are correct(
Want to see the other 29 page(s) in Biology 102 Notes for Final Exam?JOIN TODAY FOR FREE!