Energy, Life, and Photosynthesis

Energy the ability to do work

Energy comes in many forms. Can we list some? –Light –Heat –Electrical –Chemical Energy

Living things use chemical energy to get work done Which type of energy do living things use?

muscle contraction nerve impulses membrane pumps (active transport) making proteins and nucleic acids cell growth and repair make and maintain order in the cell Uses of Chemical Energy in the Body

Where in chemical compounds (FOOD) is the energy located? Energy in a molecule is in the chemical bonds formed between the atoms of that molecule. When a high-energy bond is broken and lower energy bonds are made, energy is released.

But how do living things release store and release chemical energy? Energy from food Energy for cell work

Adenosine Diphosphate a molecule by which one phosphate attaches to create ATP –like an uncharged batteryADP

ATP Adenosine Triphosphate an important chemical in life's never ending need for energy acts as a carrier of energy

extremely useful as the basic energy source of all cells the third phosphate on an ATP molecule can readily be broken (releasing energy) and reformed (requires energy) cells possess only small amounts of ATP –it is used for cell work very quickly –cells need to constantly make itATP

Animation Using the Energy in ATP and Converting ADP into ATP

Photosynthesis Textbook pages 97 – 103

Photosynthesis process used by plants using light energy to create sugar (glucose, C 6 H 12 O 6 ) from carbon dioxide (CO 2 ) and water (H 2 O) oxygen gas (O 2 ) is produced as a waste product and the light energy used is stored as chemical energy

Investigating Photosynthesis Jan Van Helmont (1643) –Carefully massed soil, and tree seedling and watered over 5 years. –Determined most of the mass of the tree came from water.

Investigating Photosynthesis Joseph Priestley (1771) –Lit a candle and placed a bell jar over it, watching the flame go out. –Reasoned that there was something in the air necessary to keep the flame going. –When a plant was placed under the bell jar, discovered that the candle could be relit after several days. –Reasoned that the plant released something into the air necessary for the flame.

Investigating Photosynthesis Jan Ingenhousz (1779) –Showed the effect observed by Priestley only occurred when plants were exposed to light.

Investigating Photosynthesis Julius Robert Mayer (1845) –Proposed that plants convert light energy into chemical energy

Photosynthesis Equation

Leaves organs where photosynthesis takes place provide a place for gas exchange

Chloroplast oval shaped organelle in plant leaf cells where photosynthesis takes place

Light plants use visible light to power photosynthesis in chloroplasts –visible (white) light is actually ALL visible colors of light –plants absorb energy from many different colors of light

Pigment material that changes the color of reflected light plants gather the sun’s energy with light absorbing pigments

Pigment the primary plant pigment is chlorophyll

Chlorophyll plant pigment that absorbs light energy very well in the blue, violet and red wavelengths of visible light Why are plants green? –chlorophyll reflects green light

Carotenoids secondary pigments absorb different wavelengths of light –produces fall leaf colors as plants break down chlorophyll –produces colors of many fruits and vegetables

Factors that affect Photosynthesis * think of the “ingredients” necessary for photosynthesis * characteristics of the ecosystem that a plant grows in can affect how well it can perform photosynthesis –some factors allow plants to make sugar quickly while other factors slow down their ability to make sugar light –length of exposure, color, intensity or brightness (distance from source) CO 2 concentration water amounts

Photosynthesis and Enzymes plants use many enzymes to produce their food made in the process of photosynthesis –enzymes are proteins that speed up chemical reactions enzyme efficiency can be affected by many factors –Temperature –pH these factors can also speed up (or slow down) photosynthesis

Connection to ATP But what do living things do with the sugar made in photosynthesis? –Eventually…living things will break down sugar and convert the energy into ATP –More on this later when we learn about cellular respiration

Summary Sometimes plants in a community will slow down or stop performing photosynthesis. This can be brought on by drought, human activities, disease, or many other factors. Describe what would happen to other members of the plants’ community.