Eat like a birdYou hear it about people who don’t eat much. People say they “eat like a bird.” Yet birds eat a larger proportion of their weight every day than even the heartiest human eaters.
Birds eat a high-energy diet of seeds, fruit, worms, insects, fish or meat---maximum energy, minimum bulk. Digestion is fast and thorough.
Food energy is spent in flight, in keeping warm-----in simply being a bird.
What is the relationship between an animal’s metabolism and the amount of food it eats? Use a comparison between birds and humans in your answer. (look in your glossary for the word metabolism)
Macromolecule Review
• 4 major groups
• Monomers & Polymers
• Functions
Concept: Enzymes
• Lesson Essential Question: How would a change in enzyme activity affect a living system?
• To understand enzymes, we have to understand basic chemistry including chemical reactions and how living things use macromolecules to chemically obtain energy for life’s functions.
Chemical Reactions & Energy
• Energy is stored or released by chemical reactions
• Bonds are broken and new bonds formed between atoms
• Different substances can be produced• Reactants are the starting materials for
chemical reactions• The newly formed substances are called
products.
Chemical Reactions
• Chemical reactions are summarized by chemical equations
• Example: 6CO2 +6H2O+sunlight energyC6H12O6 + 6O2
Reactants Products
• Arrow is read as “yields” or “forms”
Chemical Reactions
• Chemical reactions can release energy or absorb energy (also see fig. 6-15 & 6-16 in text)
Example: fossil fuel burning, respiration
Example: photosynthesis
Chemical Reactions & Life
• Metabolism is all of the chemical reactions that occur within an organism.
• Your cells get energy needed for metabolism from the food you eat.
• Chemical energy is converted into a useable form.
Chemical Reactions
• Energy is needed to start chemical reactions; we call this activation energy
• STOP: SUMMARIZE CHEMICAL REACTIONS in “Note Making” by yourself, then SHARE WITH LAB PARTNER
Enzymes
• All reactions need energy to start…called activation energy
• Catalysts are substances that speed up the rate of chemical reactions
• Enzymes are proteins that act as biological catalysts, greatly speeding up reactions in cells.
• Allows reactions to occur at much lower temperatures than normal…important for living things!
Enzymes
Enzymes, cont.
• Enzymes work because they provide a site where reactants can interact.
• The reactants in this case are called substrates• Figure 6.18 in text show how substrates bind to
the active site on the enzyme, react and then the products are released.
• Released products are things cells need to function… molecules big and small, regulating metabolism, releasing energy, etc.
Enzyme Action
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