Biology 3.17 Light and Photosynthesis

Chlorophyll

A molecule in plants that plays a key tole in photosynthesis

Which part of a lead contains all the chemicals necessary for photosynthesis?

Chloroplasts

Different kinds of photosynthetic organisms have slightly different kinds of chlorophyll

Each group or organisms has a unique set of chlorophyll molecules—which differ from reach other in a slight variation of chlorophyll a different name, such as chlorophyll A, chlorophyll B, and so forth.

The structure of chlorophyll allows it to capture energy from sunlight

Earth spins on its axis —The side facing the sun is flooded with radiant solar energy —through the actions of specific molecules, the power of the visible light energy from the sun is harnessed for the food chain of living things At the center of chlorophyll is a magnesium ion —that single atom is critical as it's involved in the absorption of visible light energy Chlorophyll absorbs red and blue wavelengths of light, and reflects green wavelengths of light. Because chlorophyll doesn't use the green wavelengths and reflects them outward, you see leaves as green when that green light strikes your eyes.

What is the first, most immediate, thing that happens when light strikes a chlorophyll molecule?

Electrons are energized

Nearly every single life form depends on photosynthesis

Example: lion bringing down a wildebeest The lion depends on photosynthesis for survival. The wildebeest fed on plants and gained its energy from glucose products of photosynthesis —then the predator (lion) ate the plant water, and the energy was passed along to the lion

The structure of a lead contains many types of cells

From the outside, most leaves are as thin as a piece of paper and not much stronger —however, they have several layers of cells

Chloroplasts have specific structures involved in photosynthesis

Green leaves have cells that contain an organelle called a chloroplast. —photosynthesis takes place in this organelle

Photosynthesis converts solar energy to chemical energy in a series of reactions

Photosynthesis converts the energy in sunlight to the energy in the bonds of glucose, but the process doesn't happen in a single reaction. —rather there's a series of reactions that take place—just as there's a series of reactions in cellular aerobic respiration

Sunlight is a type of radiant energy

Sunlight is a form of electromagnetic radiation (energy transmitted in the form of waves) —the waves differ by how long the wavelengths are. —The whole range of light can be summed up in the electromagnetic spectrum

Accessory pigments aid in the process of photosynthesis

The basic chlorophyll we see reflecting green for most plants is not the only pigment in plant cells. As chlorophyll stops being produced, leaves change color. -the colors you see are actually other pigments that were there all along, but were covered up by the dominant chlorophyll These pigments are called accessory pigments and they aid in the complex process of light-dependent reactions

Light-dependent reactions

The first stage in photosynthesis

Chloroplasts

The organelles responsible for capturing light energy in photosynthetic organisms; contain chlorophyll

Photosynthesis

The process by which plants and certain other organisms use the energy of sunlight to convert carbon dioxide and water into sugar and oxygen

Visible light

The wavelengths of sunlight involved in photosynthesis Visible light is the part of sunlight you can see. -it includes the rainbow of colors from purple to red All of the various kinds of radiation, including visible light, are sources of energy, but some visible light is the source of energy for photosynthesis

Light dependent reactions are the first steps in photosynthesis

They're basically a type of electron transport chain Sunlight storms a chlorophyll molecule. Electrons I the chlorophyll molecule become energized-or get excited- and move thru a chain of proteins in the internal chloroplast membranes As they travel, hydrogen ions are pumped across membranes, just like in cellular respiration. Their flow results in the production of ATP. in this case, the electron carrier NADPH is also generated. The electrons that become part of NADPH have to come from somewhere -they come from a molecule of a water - when water splits, oxygen gas forms and leaves the lead

What is the main purpose of the light-dependent reactions?

To energize electrons

What words are missing from the diagram?

Top should be chlorophyll, sunlight and water Middle is light dependent reactions Bottom should be oxygen, NADPH, and ATP