Energy Transformations in living things

Chemical reaction - the change of a substance into a new one that has a different chemical identity. This is represented by an “equation”.

The substances used up (required) in a reaction are the Reactants. These are on the LEFT side of the arrow in a chemical equation. The new substances made are called the Products. These are on the RIGHT side of the arrow in a chemical equation.

Photosynthesis – major chemical reaction whereby plants convert light energy into chemical energy. Chemical energy = organic compound aka: glucose/sugar

Reactants of Photosynthesis Carbon Dioxide (CO 2 ) - gas Water (H 2 O) Light energy (LE)

Products of Photosynthesis Oxygen (O 2 ) - gas major “atmospheric” byproduct Glucose (C 6 H 12 O 6 ) Sugar Carbohydrate Organic compound

All living things (organic compounds) contain carbon atoms that can be traced back to the carbon dioxide in the atmosphere.

Law of Conservation of Mass Energy is neither created nor destroyed. mass of reactants = mass of products

Photosynthesis is to light as… automobile is to gasoline.

Chloroplast Site (location) of Photosynthesis –Has double membrane –Has own DNA –Contains chlorophyll Chlorophyll = Main pigment that is responsible for absorbing the light. –“Solar panels”

Found ONLY in plants ~ therefore only plants can do photosynthesis

Two stages of photosynthesis Light Reactions – (needs the light) –occurs in thylakoid of chloroplast –Splits water keeps the electrons for energy and releases oxygen Calvin Cycle/Dark Reactions (does not need light) –occurs in stroma of chloroplast –Carbon fixation, takes the carbon dioxide from atmosphere and converts into making the carbohydrate - sugar

Environmental factors that affect the rate of photosynthesis As light intensity increases, the rate of photosynthesis increases but eventually levels off. No light = no energy to fuel process Pigments can only absorb so much light.

The Effect of Light Intensity on Photosynthetic Rate

Environmental factors that affect the rate of photosynthesis As temperature increases, the rate of photosynthesis increases to a maximum and then decreases with further rise in temperature. –Too hot, denatures the enzymes and the reaction slows down –Too hot, plant loses too much water –Too cold, KE slows and plant dies or goes dormant

The Effect of Temperature on Photosynthetic Rate

Environmental factors that affect the rate of photosynthesis As amount of CO 2 increases, the rate of photosynthesis increases but eventually levels off. –No carbon dioxide = no sugar can be made –small openings in leaves (stomata) can only take in so much CO 2

Factory Analogy

Enzymes – proteins that speed up reactions. (Catalyze = fancy word for speed up) Enzymes are very specific on which reactions they can speed up. (Lock/Key) Enzymes can be reused many times.

Substrate – the “reactants” that will undergo change. Place where enzyme attaches to substrate is called Active Site. Once the enzyme and substrate come together the reaction occurs and the Products are made

How do enzymes speed up reactions? Enzymes LOWER the activation energy in a chemical reaction. Activation energy - the amount of energy needed to start the reaction.

Enzymes names will end in “-ase” Examples: Catalase, Lactase, Oxidase

What factors affect enzyme productivity? TEMPERATURE In extreme hot temps most enzymes Denature. Denature = shape is changed If enzyme shape changes, the enzyme can't function (can’t speed up the reaction) and reaction rate slows or may not proceed at all. If the temperature becomes too cold, the rate will slow due to KE. Enzymes (proteins) are in all living things and they perform best in nice moderate warm environment.

What factors affect enzyme productivity? pH – extreme acid or base will also denature enzyme & reaction will slow down. Living things prefer neutral environment (water is pH of 7).

What factors affect enzyme productivity? Enzyme concentration - more enzymes can speed up reactions

What factors affect enzyme productivity?Substrate concentration - more reactants means more products can be produced- to a certain point

What would happen to a cell (organism) if it didn’t have enzymes? Chemical reactions would proceed too slowly to maintain life processes.

Chemical Reaction = Any process in which a chemical change occurs. Chemical Reaction = Any process in which a chemical change occurs. Exergonic reactions - RELEASE of energy ex) respiration Endergonic reactions - absorption of energy ex) photosynthesis Metabolism- ALL the chemical reactions that occur in an organism

Cellular Respiration The chemical reaction in which cells break down organic compounds (sugar/carbohydrates) to make ATP. ATP is the main energy currency of cells. (Adenosine triphosphate) Breaking down food molecules to release stored energy.

Mitochondria Site of Cellular Respiration –Double membrane –Has own DNA Found in plants AND animals ~ therefore plants and animals can do cellular respiration

What cells can perform cellular respiration? Most eukaryotic cells –Plants –Animals –Fungi –Protist Important! Remember this!!!!! –Plants can perform BOTH respiration and photosynthesis because they have mitochondria and chloroplast. –Animals can only perform cellular respiration because they only have mitochondria.

Respiration equation C 6 H 12 O 6 +6O 2 → 6CO 2 + 6H 2 O + ATP Sugar + oxygen  carbon dioxide + water + energy –Reverse/opposite of photosynthesis Reactants of respiration – glucose and oxygen Products of respiration – carbon dioxide, water, energy (ATP)

Environmental factors that affect Cellular Respiration The more sugar (glucose) available, the higher the rate of respiration. More glucose then more can be broken down to produce ATP more reactants will make more products

Environmental factors that affect Cellular Respiration As temperature increases, the rate of respiration increases to a max, then will decrease. KE is faster in warm temp until it gets too hot & enzymes get denatured (change shape). As temperature decreases (gets cold), the rate of respiration decreases until it may stop completely around freezing temp. –Due to Kinetic Energy slowing down

Light has NO affect on respiration. Respiration can occur day or night, it’s NOT light dependent.

What about oxygen? Cellular respiration makes the most amount of energy (ATP) if oxygen is available but organisms can still break down sugar if oxygen is not available, just produces a lot less energy. Oxygen present = Aerobic respiration - produces way more energy! –Krebs cycle Oxygen absent = Anaerobic respiration –Lactic acid fermentation – dairy products, muscles –Alcohol fermentation – yeast, beer/wine, bread

Photosynthesis and Respiration Create a cycle The reactants of one process are the products of the other process. (with the exception of “energy”) Example: The reactants of photosynthesis (CO2 and H2O) are the products of respiration.

Based on the cycle of photosynthesis and cellular respiration, one can say that the ultimate original source of energy for all living things on Earth is THE SUN.

 Autotroph (producer)= organism that make their own food through energy (photosynthesis).  PLANTS!!!  A few uni-cellular organisms (euglena, phytoplankton)  Algae

 Heterotroph (consumer) - organism that obtains it food by eating other heterotrophs or autotrophs.  Anything that is NOT a plant.

Specific Types of Consumer Herbivore – eat producers Carnivore – eat consumers Omnivore – eat producers and consumers Decomposer – break down dead decaying matter

Food Chain A single pathway of feeding relationships from one organism to another Transfer of energy Arrow represents the direction/flow of energy The greatest energy is closest to the sun.

Trophic Levels – the position an organism occupies in a food chain

Fewer organisms, less energy, less biomass, and lower diversity at higher trophic levels than at lower trophic levels (pyramidal shape). Each trophic level loses energy as you move up. (10% rule)

Food Web – interacting (overlapping) food chains