~What is photosynthesis?~

by: Lillian Lee

  • Photosynthesis-~The process by which plants and some single celled organisms produce sugars from sunlight and carbon dioxide
  • 6CO2+6H2O+Energy~>C6H1206+602
  • ~The light-dependent reactions is the first stage of photosynthesis, is a process by which plants capture and store energy from sunlight. In this process, light energy is converted into chemical energy, in the form of the energy-carrying molecules ATP and NADPH.
  • ~The light-independent reactions of photosynthesis are chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside of the thylakoid membranes. These reactions take the light-dependent reactions and perform further chemical processes on them.
  • Photosynthesis is the only most significant natural process to convert CO2 to O2. Photosynthesis helps to balance the Oxygen content of the atmosphere but also it helps energy balance in the ecosystem.
  • Plants are the food source in an ecosystem and photosynthesis is their only food producing mechanism.
  • Chloroplast~(in green plant cells) a plastid that contains chlorophyll and in which photosynthesis takes place.
  • Stroma~ Watery and proteinaceous ground substance. It contains ribosomes. A self-replicating DNA molecule is also present in stroma. The dark reaction of photosynthesis takes place in stroma. It is the colourless hydrophilic ground substance (matrix) which fills the internal space of chloroplast. It contains various enzymes required for the synthesis of glucose during dark phase of photosynthesis. Matrix contains 70 ribosomes, 2-6 copies circular DNA, water and enzymes. The most abundant enzyme is Rubisco (Ribulose Diphosphate Carboxylase)
  • Granum~It is embedded in the ground substance-StromaIt consists of many granums connected with each other by intergranal lamellae. Each granum is made up of stack of thylakoids. Thylakoids are membrane-bound flattened, disc-shaped vesicles. Each thylakoid consists of alternate layers of lipids and proteins embedded with quantasomes. The chlorophyll pigments are organized into numerous photosynthetic units called quantasomes. Each quantasome contains about 230 to 300 units of chlorophyll molecules. They are capable of trapping light energy and converting it into ATP during the light reaction of photosynthesis.
  • Thylakoid~ Flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana. Grana are connected by intergranal or stroma thylakoids, which join granum stacks together as a single functional compartment.
  • Some functions of Chloroplasts are the site of photosynthetic reactions, evolution of oxygen, synthesis of ATP during phosphorylation, synthesis of glucose, photosensitivity in algae, formation of chromoplast.

Main reason why chloroplasts is important~

  • Photosynthesis is one of the main things we need to survive. Its one of the major factors of why we are able to live because it is in chloroplasts and produces energy, glucose and oxygen.

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