Big Idea #2

1. Big Idea #2 Biological systems utilize energy and molecular building blocks to grow, to reproduce, and to maintain homeostasis.

2. Free Energy • Growth, reproduction and maintenance of the organization of living systems require free energy and matter. • Energy moves through all biological organisms and systems • Cells use energy in the form of organic molecules • Energy is stored in and released from chemical bonds • Cells utilize cellular energy in the form of ATP (easy to form and easy to break to access the stored energy.

3. Catabolic vs. Anabolic • Catabolic reactions break down molecules and release energy • Anabolic reactions build larger molecules and require energy input

4. Importance of Water • Properties of Water • Polarity • Hydrogen Bonding • Adhesion • Cohesion • High specific heat • Universal solvent • Solute • Solvent • Solution • High heat of vaporization

5. Cell Size limitation • Cells require a high surface area to volume ration. This limits their size • Examples of cellular structures designed to maximize exchange of materials by increasing surface area to volume ratio: • Root hairs • Alveoli • Villi and microvilli

6. Metabolic Strategies • Ectothermic vs. Endothermic • Ectothermic = cold blooded. Cell environment fluctuates with the environment • Endothermic = warm blooded. Maintain consistent cell environment that is different than environment. High metabolic rate. • Osmoconformers= aquatic animals that maintain internal conditions to fluctuate with the environment • Osmoregulators= aquatic animals that maintain internal conditions that are different from the outside environment. Metabolic activity is necessary to maintain these conditions.

7. Capturing and Storing Free energy • Autotrophs = capture free energy from environment “make their own food” Phototroph (Photosynthetic) = use sunlight as energy source Chemotroph (Chemosynthetic) = use inorganic molecules as energy source • Heterotroph = captures free energy by consuming other organisms. “make their own food” Phototroph (Photosynthetic) = use sunlight as energy source Chemotroph (Chemosynthetic) = use inorganic molecules as energy source

8. Anaerobic Respiration • Without oxygen: Yields 2 ATP • Two stages: Glycolysis and fermentation (alcoholic or lactic acid) • Glycolysis: Happens in cytosol. Glucose converted to two molecules of pyruvate. Yields 2 ATP and 2 NADH • Alcoholic Fermentation: two pyruvates are converted to ehtanol: NADH is converted back to NAD+ to keep glycolysis going. • Lactic Acid Fermentation: two pyruvates are converted to lactic acid. NADH is converted back to NAD+ to keep glycolysis going.

9. Aerobic (Cellular) Respiration • Occurs in Cells • Four stages • Glycolysis: Occurs in cytosol. Glucose is converted to two molecules of pyruvate, 2 ATP, and 2 NADH • Pyruvate oxidation: two pyruvates enter the mitochondrial matrix. They are converted to 2 Acetyl CoA which go on to the Krebs Cycles; and 2 NADH which go on to oxidative phosphorylation. • Krebs Cycle: Occurs in mitochondrial matrix. Two turns of the cycle convert the 2 Acetyl CoA molecules into: 6NADH, 2FADH2, and 2 ATP • Oxidative Phosphorylation (electron transport and chemiosmosis): happens in the cristae. The NADH and FADH2 molecules donate electrons to the electron transport chain. As they move through the chain their energy is used to pump H+ ions into the innermembrane space. The H+ ions then move down their concentration gradient through ATP synthase to make 34 ATP molecules (chemiosmosis)

10. Summary of ATP generated from Cellular Respiration

11. Photosynthesis • Energy from sun is converted into chemical energy of sugar • Occurs in autotrophs (mostly in chloroplasts) • Stages: • Light Reactions: Occurs in the thylakoid membranes • Light energy is absorbed by chlorophyll molecules in Photosystems I and II which are embedded in the thylakoid membranes. • Electrons become excited and move down an electron transport chain from photosystem I to photosystem II. Their energy is used to pump H+ ions into the stroma. • Electrons lost from Photsystem II are replaced from the electrons lost by the splitting of water molecules. Electrons lost from Photosystem I are replaced by electrons lost from Photosystem II. • H+ ions build up in the stroma and move down their concentration gradient through ATP synthase to generate ATP (chemiosomsis)which will go on to the Calvin Cycle. • NADPH is also generated through the use of the enzyme NADP reductase. It will also go onto the Calvin Cycle.

13. Calvin Cycle • Most common pathway for Carbon fixation (taking CO2 and converting it into organic molecules) • Does not require light • Happens in the stroma of the chloroplasts • The enzyme Rubisco and the energy from ATP and NADPH is used to bind CO2 to organic molecules. It is a multi-step process in which G3P is produced. This molecule can be converted into various types of molecule including glucose.

15. Cell Membranes • Cell membranes play a critically important role in maintaining dynamic homeostasis. • Selectively permeable • Constant movement of molecules in and out • Membrane itself is a fluid mosiac • Membrane Structure • Phospholipid bilayer: Hydrophilic, polar heads (phosphate group); hydrophobic, nonpolar tails (fatty acids). • Peripheral proteins: Lie on inside or outside • G-proteins that relay signals (inside) • Receptor or signal proteins (outside) • Integral embedded proteins: bridge both layers • Amphipathic • Types: channel, receptor, recognition, membrane pumps • Cholesterol molecules: maintain fluidity and prevent freezing • Oligosaccharides: short carbohydrate chains attached to proteins: act as signals

16. Identify the parts of the cell membrane

17. Membranes allow for Cellular diffusion and osmosis to occur • The membrane’s structure facilitates easy diffusion of small, nonpolar, or uncharged molecules into and out of the cell. (Simple diffusion) • Polar molecules or charge molecules (ions) will only pass through protein channels. (Facilitated diffusion) • In both processes, molecules move from high to low concentration. • Osmosis is the movement of water from high to low concentration or high to low water potential. Most water moves through proteins known as aquaporins. • Hypotonic solutions= water moves in • Isotonic solutions= water is in equilibrium • Hypertonic solutions= water moves out

18. Identify the type of tonicity

19. Active Transport, Endocytosis and exocytosis • Active Transport moves molecules through membranes from low to high concentration and requires the input of ATP • Example: Sodium/Potassium Pump • Endocytosis: type of Active Transport involving the uptake of very large molecules or particles • Types: Phagocytosis, Pinocytosis, Receptor-mediated endocytosis • Exocytosis: type of Active Transport involving the release of very large molecules or particles

20. Sodium potassium pump

21. Cell Walls Have a Structural and functional purpose • Cell walls are found in plant cells, bacterial cells and fungal cells • Plants = cellulose • Bacteria = Peptidoglycan • Fungi = Chitin

22. Eukaryotic Cells have internal membranes around organelles • Endomembrane system: • Nucleus • Rough ER • Smooth ER • Golgy • Lysosome • Vesicles • Vacuole

23. Several organelles are not part of the endomembrane system • Mitochondria • Chloroplasts • Ribosomes • Flagella • Cilia • Centriole

24. Feedback mechanisms help to maintain dynamic homeostasis • Positive Feedback= cellular processes increase the rate of chemical reaction or cellular processes. This often leads to a greater degree of instability. • Examples: Labor Contractions(Oxytocin production) Fruit ripening (Ethylene production) • Negative Feedback = when a condition or chemical inhibits some cellular process and often maintains stability • Examples: Insulin regulation

25. Responding to environmental changes • Plants: • Photoperiodism= effect of the length of day and night on plant growth. • Phototropism= direction of plant growth is towards the light • Annual reproduction = complete life cycle in one growing season • Biennial= entire life cycle in two years • Perennial= grow and bloom every year • Animals • Kinesis= random movement in response to a stimulus • Taxis= directional movement towards or away from a stimulus • Chemotaxis • Phototaxis • Gravitaxis • Circadian Rhythms= daily behavioral responses (internal clock) • Chemotaxis • Phototaxis • Gravitaxis

26. How the environment affects dynamic homeostasis in living systems • All living systems are affected by biotic and abiotic factors. • Biotic = living • Abiotic = nonliving • Energy flows through trophic levels (feeding patterns in a community that are involved in energy transfer) • Food Chains= simple feeding relationships • Food Webs= complex feeding relation ships

27. Energy Pyramids • Only 10% of available energy passes from one trophic level to the next.

28. Ecological Succession • Ecological succession refers to the gradual changes that occur to the structure and energy demands of an ecosystem • Types: • Primary succession= when life begins to form in an area that is devoid of life or soil. (Ex: following volcanic eruption or in an abandon parking lot) • Secondary succession= occurs when change happens to an existing community or a new community grows where there is intact soil with seeds in the seed bank. Often follows fire, flood, tornadoes, earthquakes, etc.

29. Community Interactions • Interspecific competition= two species compete for limited resource • Competitive Exclusion principle= theory that one population will always be a better competitor and will outcompete the other to the point of extinction in that area. • Resource partitioning= can allow different populations of animals to share a limited resource by utilizing that resource in a different way. • Symbiotic Relationships • Commensalism • Mutualism • Parasitism • Predation

30. Mechanisms to exchange nutrients and wastes with environment • Plants: exchange gas through stomata • Animals: • Aquatic: exchange gas through gills using a countercurrent exchange system. Gills are a good example of increased surface area • Terrestrial: exchange gas through skin or lungs (another good example of increased surface area) • Excretion in aquatic animals : secrete ammonia • Excretion in terrestrial animals: urine (hyperosmotic urine prevents dehydration. • Birds and reptile secrete uric acid to allow for more water retention.

31. Variations in Circulatory systems • Fish: two chambered heart and a single loop pathway for circulating blood. • Amphibians: three chambered heart and a double loop circulation pathway. • Mammals: four chambered heart and a double loop circulation pathway. Most efficient

32. Immune response contains nonspecific and specific mechanisms to maintain homeostasis • Nonspecific immunity: physical barriers, cilia, mucus, pH of skin and body fluids, leukocytes, inflammation, natural killer cells, fever. • Specific immunity: humoral (B cells, plasma cells, antibody production); cell mediated (T cells: cytotoxic and helper)

33. Regulation and timing of cellular events control development • Cell differentiation is regulated by gene expression and cell signaling • Transcription regulated by transcription factors • Homeotic genes control the pattern of body formation of an embryo • Embryonic induction is controlled by tissue development • Apoptosis (cell suicide) is controlled by extracellular or intracellular signals • Seed germination is controlled by hormones (gibberillin, abscisic acid and ethylene

34. Regulation and timing also control population interactions • Hibernation (winter) and estivation (summer) are periods of reduced metabolic activity • Pheromones are chemical signals that trigger specific social responses. • Visual displays important for reproduction in many species • Quorum sensing important for bacteria