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Transcript
AP Biology • During development an organisms cells differentiate from Stem cells • Stem cell – any unspecialized cell that can produce, during a single division one identical daughter cell and one more specialized daughter cell • This occurs via structural and functional divergence of cells Cell Specialization 1. 2. 3. 4. 5. 6. Molecular level (chemicals) Cell Tissue Organ Organ system Organism Cellular organization Feedback Disruption Physiological Homeostasis • Defense • Development Response Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Negative – Reduces frequency, regulates physiological processes back to a target set point (long term) • Positive – Increase frequency or amplify processes (short term) Positive and Negative feedback Target set point Negative feedback Stabilization Temperature regulation Plant responses to water Positive feedback Amplification Fruit ripening Child birth Lactation in mammals Regulator Vs Conformer Temp. regulation To become attractive plants produce fruit, this makes them desirable so animals will take and carry off their seeds. Plants communicate via ethylene – a gas • Lactation in mammals – When baby drinks milk, hormones prolactin and oxytocin are released, this causes milk to be released and produced. • Child birth – pressure on cervix causes contractions. Contractions cause more pressure • Blood clotting – vascular spasms Decrease blood flow, plug formation, coagulation Other Positives • Some changes to homeostasis are regulated and many are controlled by hormones. • Examples: • Women’s menstrual cycle • Circadian rhythm (changes that occur every 24 hours) • Acclimation- gradual process in which animal adjusts to external environment Alteration of feedback Normal alterations • Thermoregulation – process by which animals maintain an internal temperature • Endothermic – warmed by heat they generate via metabolism • Ectothermic – gain heat via external sources Maintaining homeostasis physiological • Balancing Heat Loss and gain • • • • Integumentary system Insulation Circulatory adaptations Cooling via evaporative heat loss Maintaining homeostasis • Increases blood flow to help keep warm • Decreases blood flow to help keep cool Maintaining homeostasis • Countercurrent exchange- exchange of heat via fluids or between fluids that are moving in the opposite direction Maintaining homeostasis • • • • • Maximize sunlight absorption Postures Huddling together Torpor Hibernation Maintaining homeostasis behavioral Feedback Disruption Physiological Homeostasis • Defense • Development Response Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Homeostatic disruptions are anything that affects the individual or the environment in which the individual lives in • Can be: • Molecular level • Ecosystem level Disruptions In Homeostasis • Problem in feedback loops • Can be • Type I (juvenile or child onset) • Type II • Both cases cells are not communicating in the feedback loop dealing with blood sugar Diabetes Diabetes Insulin Blood glucose glucagon Alteration of feedback Dehydration: Molecular disruption 1-2% loss increase in body temperature, thirst, discomfort, loss of appetite, dry skin, constipation 5% loss All above and: headaches, increased heart rate, nausea, tingling limbs 6% loss All of the above and: muscle spasms, cramping 10% loss All above and: susceptibility to heat stroke, circulatory collapse, vision dims, urination stops 50% loss death Molecular disruption • Invasive species: A species, often introduced by humans, that takes hold outside its native range Ecosystem disruptions Feedback Disruption Physiological Homeostasis • Defense • Development Response Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Response: Anything an organism does as a result of its surroundings • Can be: • Behavioral • Physiological Form and Function • Occurs as a population or a group of organisms • Examples: 1. Hibernation 2. Migration Can be learned or inherited Behavioral Responses • Changes within the organism • Examples: 1. Shivering 2. Sweating- evaporative cooling Physiological responses Feedback Disruption Physiological Homeostasis • Defense • Development Responses General Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Plants and animals defend themselves from pathogens • Pathogens- invaders • 2 major forms of defense: 1. Nonspecific 2. Specific Physiological-Defense • Kills anything that invades (skin, saliva, normal bacteria, swelling, inflammation etc.) • Plants sense pathogens using Hypersensitive Responses Nonspecific • R gene in chromosomes – senses invading proteins • R gene will initiate a hypersensitive response • Oxidative burst – apoptosis • Proteins sent to adjacent cells will change cell wall • Memory does not occur Nonspecific - hypersensitive • Specific responses identify pathogens and attack them • Occurs in 2 forms: 1. Humoral – occurs in humor/liquid/blood/lymphatic 2. Cell mediated – target infected cells Specific • • • • Humoral responses are governed by B cells B cells produce memory Antibodies Antibodies target invaders Invaders are called antigens - Humoral • Antibodies have antigenbinding sites • Antigen- is an antibody generating organism • fungus, bacteria, virus etc. Humoral 1. Antigen present – invader 2. Antigen is engulfed (eaten) by a WBC or macrophage 3. WBC will take some of the antigen and put it on the surface of its cell (Antigen Presenting Cell) 4. Helper T cells- recognize the shape of the antigen 5. Helper T cells- activate B cells to make antibodies a. plasma B – makes antibodies b. memory B 6. B cells invade antigens Humoral • This response targets infected cells • Called cytotoxic T cells – kills own cells that are infected Cell-mediated Feedback Disruption Physiological Homeostasis • Defense • Development Responses General Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic How does this happen? Physiological- Development • Seed Germination – • When planting seeds it needs 2 things to survive (water and temperature) must be in correct combination • Germinating cells will appear different Physiological • First step in development is cellular differentiation • DNA will express specific proteins that determine each tissue – called tissue specific proteins • Cells will eventually specialize Physiological • Zygote makes a copies of itself • Forms a sphere (blastula) • Blastula folds in on itself (gastrula) forms ectoderm, mesoderm and endoderm • Transcription factors give off proteins that help to determine what should happen Physiological - differentiation • Step 2 is embryonic induction: • Cells induce other cells to become like them, give off proteins • Cells induce adjacent cells next to it Physiological - induction • • • • Just as important as cell growth Hid, Grim, Reaper Genes These genes are needed between fingers and toes etc. microRNA genes – control hid, grim, reaper genes Physiological – cell death • How do cells “know” the body plan of organisms? • Homeotic genes – are a series of genes that “tell” drosophila where to put the organs/appendages etc. • Famous ones are HOX genes We learned from the mutants Ultrabithroax will duplicate the thorax Antp- one leg will grow of the head Series of genes that codes for body plan Physiological- Homeotic genes Feedback Disruption Physiological Homeostasis • Defense • Development Responses General Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic When traveling – especially across time zones jet-lag occurs Timing and control 1. Phototrophism – how plants grow toward or away from light Toward light + Away from light – Hormone: Auxin Timing and control - plants 2. Photoperiodism – how plants respond to changing amounts of light during the season Phytochrome – light receptor- when absorb light, will change shape to let plant know what time of day and season it is (regulates cellular activities) Timing and control - plants • Circadian rhythms – • Animals sense light• Sent to pineal gland • Releases melatonin which sets internal clock Timing and control - animals • Bacteria use Quorum Sensing • How bacteria talk or communicate with each other • Can be among species or between species • Bacteria give off autoinducers Timing and control – bacteria Where does evolution fit? Feedback How does change support homeostasis??? Disruption Physiological Homeostasis • Defense • Development Responses General Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Homeostasis reflects BOTH common ancestry and divergence!!! • Continuity • Change Homeostatic evolution • Excretory system – All serve same purpose (get rid of waste) • Flatworms • Earthworms • Vertebrates Continuity - Example • Excretory system called Protonephridia • Protonephridia forms networks of tubes connected to external openings • Flame bulbs (cells) is how waste moves out of the platyhelminthes • Rotifers, some annelids, mollusc larvae, and lancelets flatworms • Earthworms contain segments have Metanephridia • Metanephridia are excretory organs that collect fluid directly from the coelom • Each segment has one • Cilia funnel surrounds the opening which excretes waste out of earthworm Annelids • Kidneys are present, function in osmoregulation and excretion • Kidney tubules – nephron Vertebrates Continuity – Each phylum of organisms has a way to get rid of waste. Each are similar but with modification “descent with modification” Common ancestry • Homeostatic mechanisms also support change in response to changing environments • Vertebrates must have oxygen in their environment, must have water in their environments Change • Example – Respiratory systems • Aquatic • Terrestrial change Where does evolution fit? Feedback How does change support homeostasis??? Disruption Physiological Homeostasis • Defense • Development Responses General Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Organisms exhibit complex properties between organs and systems • Example: Respiratory and Circulatory systems Homeostasis contd. Homeostasis Homeostasis Homeostasis Nervous System works with all systems How does nervous system function?? Relay system 1. 2. 3. 4. 5. 6. 7. Homeostasis Stimulus Receptor Afferent pathway Integration center Efferent pathway Effector organ Response N.S Peripheral Somatic Central Autonomic Parasympathetic Sympathetic Divisions of nervous System Nerve impulses Nerve impulses Steps: 1. Resting (polarized) Na+ Na+ Na+ Na+ K+ K+ Na+ Na+ K+ Na+ Na+ Nerve impulses Na+ • Step 2 Depolarization (polarity is reversed) Nerve impulses • Step 3 Repolarization • initiation of sodium potassium pumps • Restores initial electrical configuration Nerve impulses Feedback Disruption Physiological Homeostasis • Defense • Development Responses General Environment Behavioral • Timing and coordination of events Biotic Form and Function Abiotic • Fixed action pattern Ex: sticklebacks Behaviors • Migration – using environmental cues to guide regular, longdistance change in location Behaviors • Courtship – fixed behaviors 1. Visual communication 2. Chemical communication 3. Tactile communication Behaviors • Cortship Behaviors • Honey bee Dances Behaviors Behaviors Behaviors • Innate behavior – developmentally fixed within an organism • Learning- the modification of behavior based on specific experiences Behaviors • Imprinting – formation at a specific stage in life a long-lasting behavioral response to a particular individual or object Behaviors • Associative learning – associate environmental features with another Behaviors Classical Conditioning – Pavlov’s dog Operant conditioning – trial and error • Social Learning: Behaviors • Foraging – food-obtaining behaviors Behaviors Behaviors • Mating Systems and Mate Choice • Promiscuous mating – no strong pair bond • Monogamous – mates remain together for a longer period • Polygamous – one male and several females or visa versa Behaviors • Altruism – selflessness, reduces an animal’s individual fitness, but increases the fitness of the others in the population Behaviors