Peroxisomes:
Peroxisomes break down large fatty acids and amino acids. They also remove hydrogen atoms from biomolecules and combine them with oxygen atoms to form hydrogen peroxide (H2O2). However, since H2O2 is toxic, peroxisomes must then break it down into water and oxygen.
Centrioles:Centrioles are a pair of rod-shaped organelles near the nucleus. There are 9 tubes in each one, and each tube has 3 tubules. They lay at right angles to each other. Their main job is to move chromosomes during cell division. Further, centrioles are also involved in the creation of cilia and flagella. These organelles are usually not present in plants.
Cell Wall:Cell walls are found on plant cells and not on animal cells. They function primarily to help cells maintain a rigid shape. In addition, it is semi-permeable, meaning that it acts as a physical filter where large molecules cannot pass through.
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Chloroplasts:Chloroplasts are only found in plants. These organelles are the sites of photosynthesis. Similar to mitochondria, they have their own DNA. This means they control their own reproduction and protein synthesis. Chloroplasts have a double membrane. Inside the membranes, there are grana, which contain chlorophyll. This green pigment converts CO2 and water to carbohydrates using the sun's energy. Grana are stacks of many thylakoids (flattened sacs which resemble pancakes). Finally, stroma is the fluid-filled space inside the chloroplast, much like what the cytosol is to the cell.
The photosynthesis equation: 6CO2 + 6H2O + light energy -> C6H12O6 + 6O2 In short, chloroplasts are the food producers for the world. |
Cytoskeleton:
This is a system of protein fibers which helps the cell maintain shape, keep organelles in place, and move materials within the cell. There are three kinds of protein fibers. Microfilaments are elastic and can move organelles within the cell. It is also responsible for cell amoeboid movement. Microtubules are another kind of fiber which helps the cell maintain its shape. They also make up cilia and flagella. During cell division, they help move chromosomes. The third type of fiber are intermediate filaments, which support the nuclear envelope.
Cilia and Flagella:
Both of these are hair-like projections from the cell which are made from microtubules. First, cilia are short stiff "hairs" that help a cell move itself. Think of them as tiny little oars that move a ship. They are very important for cells that swim and for cells that sweep materials towards a certain direction (like epithelial cells in our airway). Second, flagella are longer than cilia, but often appear in smaller numbers. It resembles a whip and helps a cell swim (like sperm cells).