Energy Energy – the ability to make something happen ENERGY exists in different forms, but can CHANGE from one form to another. Some types of energy are: Light (solar) Electrical Chemical Infrared (heat)
“Solar cells” convert LIGHT (solar) energy into ELECTRICAL energy (electricity). Light bulbs convert ELECTRICAL energy back into LIGHT (and heat!) energy. This is one way humans store ENERGY for later use.
EVERYTHING has some form of energy, or a COMBINATION of different forms of energy. A light bulb has LIGHT and HEAT energy to offer. Remember: All energy originally comes from the SUN. Energy CANNOT be created Energy cannot be DESTROYED But, energy CAN be transformed The energy to power your iPod came from the sun, originally. Have you thanked your Sun recently???
Have you ever used a solar-powered calculator? No matter where you go, as long as you have a light source, the calculator works. You never have to put batteries in it. Where does the energy to power the calculator come from? What form (light/heat/chemical/electrical) of energy is this? A solar cell transforms this energy into ___________ energy, which powers the electrical circuits of the calculator. Do all calculators run on solar energy?
Have you ever noticed that your body maintains a constant temperature, usually 98o F? This energy, measured by temperature, is HEAT energy. Which object has more heat energy, an ice cube or a hot cup of coffee? What happens when you put the ice cube into the hot coffee? It melted, but why? The energy moved from the coffee (area of higher energy) into the ice cube (area of lower energy), giving it enough energy to melt. Since energy moves from an area with lots of energy to an area with lower energy, what happens to the air next to your skin on a cold day? When you use a wood stove to put energy into your house, what happens to the temperature inside your house? Where did the energy come from to heat the stove? Where did the energy in the wood come from?
The energy in the wood from the last example came from the SUN, originally. The wood has lots of trapped CHEMICAL energy. Chemical energy is stored in the BONDS between molecules of the wood. These bonds are BROKEN when wood is burnt. When chemical bonds are broken, energy is RELEASED. How did the wood transform energy from the sun (light energy) into chemical energy? Photosynthesis– making chemical energy from light energy Photosynthesis Photo – “light” Synthesis – “making”
Energy in Organisms Just like our appliances, iPods, and light bulbs have energy flowing through them, energy flows through LIVING things! Energy to power LIFE originally comes from the SUN, just like all other energy. Energy from the sun enters living systems through “producers,” such as autotrophs. Autotrophs – make their own food by photosynthesis gathers LIGHT energy and stores it as CHEMICAL energy in GLUCOSE.
What are examples of autotrophs? Plants Oak tree Grass Wheat Moss Flowers Shrubs Every other plant you can think of. Algae Algae are not considered plants – they are unicellular. Certain kinds of bacteria
Comparing Autotrophs Photoautotrophs Vs. Chemoautotrophs
Photoautotrophs Convert light energy into chemical energy stored in organic compounds (usually glucose). This is PHOTOSYNTHESIS Source of energy is the SUN Examples: Plants, algae, and other “green things” with photosynthetic pigments (such as chlorophyll).
Chemoautotrophs Use small, inorganic molecules to make larger organic molecules that sustain life Eg) CO2, NH3, NO2-, H2, Fe2+ Usually don’t need sunlight Many archaebacteria are chemoautotrophs Found deep in ice-core samples in Greenland Found in extremely salty conditions Found on bottom of ocean in near-boiling water
Heterotrophs Organisms that must get energy from food instead of directly from sunlight or inorganic substances. Heterotrophs extract the energy from food through the process of cellular respiration. Cellular respiration produces ATP Includes: animals, fungi, some protists, some bacteria
PHOTOSYNTHESIS Process that converts LIGHT energy into CHEMICAL energy. MEMORIZE THE FORMULA!!! H2O + CO2 + LIGHT C6H12O6 + O2 Water Carbon DioxideGlucose Oxygen
How does the plant get CO2 and release O2? Leaf plant organ where photosynthesis occurs Stomata small pores underneath the plant leaf where carbon dioxide and oxygen to diffuse in and out Guard Cells cells that surround stomata that open and close according to water pressure
Equipment Used The Chloroplast is where photosynthesis occurs in the plant The chloroplast has an inner and outer membrane. The inner membrane forms disk-shaped structures called thylakoidswhich has chlorophyll embedded in it. Thylakoids arranged in stacks called grana The space around the thylakoids is the stroma
Pigments Pigments (such as CHLOROPHYLL) reflect the colors that they can NOT absorb. Ex: a red shirt can absorb orange, yellow, green, blue, indigo, and violet but can NOT absorb red so it reflects (and appears) red to your eyes. QUESTION: Which color light will be more effective for plant growth? Yellow Green Red
What color of light is absorbed the most by Chlorophyll b?
What color of light is absorbed the most by Chlorophyll a?
Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyllb Chlorophylla V B G Y O R
Pigments Chlorophyll isn’t the only pigment in plants. Accessory pigments - absorb different wavelengths (colors) of light than chlorophyll allowing the plant to absorb more light energy during photosynthesis. Carotenoids – appear orange and yellow Give the fall leaves their colors
PHOTOSYNTHESIS: STEP 1 Step 1 – Light-Dependent Reactions Chlorophyll in the thylakoid membrane absorbs photons (light energy), which excites electrons Electrons bounce down an “electron transport chain” (ETC) ETC – a group of integral membrane proteins that ferry electrons As electrons pass through, these proteins pump H+ across the membrane Wateris broken to resupply lost electrons Byproducts: Oxygen and H+ H+ gradient powers ATP formation Electrons hop off the chain and onto NADP+, forming NADPH.
Products of Light Reactions ATP and NADPH (high-energy compounds) Needed to power the next step Oxygen (released into atmosphere)
PHOTOSYNTHESIS: STEP 2 STEP 2 – Dark Reactions aka. Calvin cycle Occurs in the stroma Does NOT require light The ATP and NADPH produced in the light-dependent reactions is used to power the conversion of CO2 into glucose (C6H12O6) NADPH converted back into NADP+ ATP converted back into ADP Both NADP+ and ADP go back to the light reactions to get recharged
Chloroplast – Overview of Light-Dependent Reactions and Calvin Cycle