Energy in a Cell Photosynthesis Energy in a Cell •Cell processes require energy. Energy in a Cell • Examples of cell processes: muscles contracting, cells growing, brain thinking, and cell transport. Energy in a Cell • Cells get energy from a special molecule called ATP (Adenosine Tri Phosphate). Energy in a Cell •When one of the phosphate groups is removed, energy is released. Energy in a Cell •ATP becomes ADP (Adenosine Di Phosphate). Energy in a Cell •This reaction is facilitated by enzymes. Energy in a Cell •ATP acts like a rechargeable battery. Photosynthesis • Photosynthesis: process in which plants use light energy to convert CO2 and H2O into sugar and O2. Photosynthesis •Photosynthesis takes place in the chloroplast. Photosynthesis Photosynthesis •Chloroplasts are double membrane organelles that float in the cytoplasm. Photosynthesis •Inside are numerous flattened sacs called thylakoids. Photosynthesis •Thylakoids contain the chlorophyll. Photosynthesis •Stroma is the dense substance that surrounds the thylakoids. Photosynthesis •Photosynthesis is divided into two separate reactions. Photosynthesis •Light dependent reaction takes place in the thylakoid; requires chlorophyll. Photosynthesis •H2O is split and O2 is released and H+ ions are formed. Photosynthesis •ATP is made from ADP. Photosynthesis • Light independent reaction: uses energy (ATP) from the light dependent reaction to form sugars from CO2. Photosynthesis •Also called the Calvin Cycle. Photosynthesis •This reaction takes place in the stroma.