Chapter Two Energy, Life and the Biosphere

Organizer Write five questions on each of the following three statements: Living things need energy. The need for energy and nutrients links organisms in many complex ways. Energy conversions are described by the principles called the laws of thermodynamics.

Characteristics of Organisms What are some characteristics of living things?

Characteristics of Organisms Convert Material/ Energy Chemical Organization Structural Organization Coded Instructions Sense/ React to Environment Grow and Develop Reproduce Communicate Move Under Own Power.

Energy and Nutrients Organisms store energy in organic molecules – chemical energy. Autotrophs synthesize organic compounds (photosynthesis, chemosynthesis) Heterotrophs obtain energy from other organisms. Energy is released through cell respiration.

Energy and Ecosystems ProducerConsumerDecomposerFood Web Energy FlowNutrient CycleAbioticBiotic

Energy and Ecosystems An ecosystem is the biotic and abiotic components of a place. Examples? Habitats are where in an ecosystem organisms live. All of Earth’s ecosystems is the biosphere.

Energy Conversions How does energy flow? Energy cannot be created or destroyed – it can change form: the first law of thermodynamics. The law of conservation of energy states: total energy of the universe is constant.

Energy and Entropy Systems tend to change toward entropy or disorder. Energy moves from an ordered to disordered form. Examples? Second law of thermodynamics.

Energy and Entropy Explain the following: Organisms stay organized and can function and grow only as the entropy of their surroundings increase.

Enzymes and Energy Chemical energy is released from breaking chemical bonds. High temperatures/ high activation energy are needed. Enzymes are protein catalysts that lower the activation energy of reactions.

Enzymes and Energy Enzymes are specific – catalyze one or two reactions. The active site of the enzyme must fit the starting molecule or substrate. Substrates can be broken down or combined by the same enzyme. Example?

Enzymes and Energy Several thousand enzyme reactions take place in each cell every minute. Enzymes are most active at a certain temperature and pH. Temperature example? pH example?

Chemical Reactions in Organisms Metabolism consists of all the chemical reactions in a cell or organism. Synthesis is building up, absorbing energy. Examples? Decomposition is breaking down, releasing energy. Examples?

Energy Transfer and ATP How do we obtain energy? Oxidation is the removal of electrons from a molecule to release energy. In reduction, those electrons are donated. Free energy ultimately winds up as the molecule ATP – energy currency.

Energy Transfer and ATP ATP  ADP What happened? The bond between the 2 nd and 3 rd phosphate breaks releasing free energy.

Digestion Heterotrophs must break down large food molecules into their monomers: monosaccharides, amino acids and triglycerides. Why do we need smaller molecules? The processes that break down food are known as digestion.

Digestion Physical digestion involves such parts as gizzard in birds and teeth in humans. How does increasing surface area aid digestion? Chemical digestion breaks down complex molecules to simple molecules. How do enzymes work?

Digestion Most animal rely on extracellular digestion – food digested outside the cell. What is the role of the digestive tract? Plants rely on intracellular digestion – self made starches. Fungi and mold digestion …

Human Digestion Ingestion is the taking in of food – chemical and physical digestion occur between the teeth and the saliva. Food is swallowed past the epiglottis to the esophagus. How does food move? Muscle contractions called peristalsis moves food through the digestive tract.

Human Digestion What is the role of your stomach? The stomach mixes food with enzymes, mucus and acid – 4 hours. Partially digested food is released to the small intestines where digestion continues and absorption takes place.

Human Digestion Undigested food is moved to the large intestine where water and vitamins are absorbed. Feces are eliminated through the anus.

Absorption Slivary amylase begins the digestion of starch in the mouth  maltose. What pH would it work best at? Starch digestion ends in the small intestine  ? What is the end product?

Absorption Protein digestion occurs in the stomach and small intestine. At what pH does protein digestion occur best? Food in the stomach elicits the release of the hormone gastrin which causes the release of HCl.

Absorption Pepsinogen is released in the stomach and is changed to pepsin by HCl. Proteins are broken down to smaller polypeptides. What are the monomers of proteins?

Absorption Pancreatic juices enter the small intestine switching the pH from acidic to basic. Intestinal enzyme trypsin further breaks peptide bonds producing amino acids.

Absorption Fats are also digested in the small intestine. Do fats mix with water? Bile from the liver/ gallbladder emulsifies fats. Lipase breaks lipids into fatty acids and glycerol.

Absorption End products of digestion: Amino acids Simple sugars Glycerol Fatty Acids Small molecules pass through small intestines into capillaries. Villi increase the surface area of the intestines – why is that important?