Photosynthesis

Previously you read about autotrophs and heterotrophs.  The difference being in the way they obtain energy.  Plants are autotrophs, and today I’d like to focus on how plants get the energy they need.

Plants need the following things to get energy to live:

• Water (H2O)
• Carbon Dioxide (CO2)
• Sunlight

The process of converting H2O and CO2 in the presence of sunlight into energy is called photosynthesis.

In order for the water to get to the leaves of a plant where photosynthesis takes place, it is absorbed from the surrounding ground through roots and is brought up through tissue like your blood vessels.

The carbon dioxide is absorbed my the leaf directly through openings (or pores) on the under side of the leaf.

Light-absorbing molecules called pigments capture sunlight for the plant.  The primary pigment in plants is called chlorophyll.  Chlorophyll gives plants their green color because it absorbs reds and blues and reflects green!

Chlorophyll is housed in organelles called chloroplasts.  This is where photosynthesis takes place.

The equation for synthesis looks like this:

6CO2 + 6H2O (in the process of light) -> C6H12O6 + 6O2

carbon dioxide (in) + water (in) -> glucose (used for energy) + oxygen (out)

(That’s the same oxygen we need to breathe!!!)

All that happens in plants which are pretty fascinating, even if they aren’t furry and cuddly!

The Cell II

After covering the animal cell, I’d like to talk just briefly about a few other types of cells.  We’ll go over plant cells and prokaryote cells.

Plant cells

Plant cells are very similar to animal cells.  Major differences are that plants have a cell wall outside of their cell membrane.  The cell wall provides structure, support, and protection for the cell.  Plant cells also have chloroplasts which are an organelle used to capture sunlight energy and make glucose (food).  The chloroplasts are what give plants their green color; chloroplasts are filled with a green pigment called chlorophyll.  The last major difference is that plant cells tend to have one large, central vacuole (when present in animal cells, they are smaller) which serves to house waste and add structural support.

Prokayote cells

Prokaryotes, organisms without a nucleus (like bacteria), are even more different from plant and animal cells.  They also lack other membrane-bound organelles such as mitochondria and chloroplasts.  Prokaryotes tend to be unicellular, unlike plants and animals.  While they do have DNA, it is in the form of chromosomes you are used to seeing; it tends to be in simple circle or tangled-looking loop shape.