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Biology: Cell biology

Grade 9 · Science · Free lesson

Welcome to the amazing world of biology! Today, we are going to explore the tiny, bustling cities that make up every single living thing on Earth: cells.

Every living organism, from the giant blue whale to the smallest blade of grass, is made of cells. You can think of a cell as a microscopic factory, working non-stop to keep you alive and energetic!

artery

The control center of this cellular factory is called the nucleus. It holds the DNA, which acts like a master instruction manual telling the cell exactly how to grow, function, and behave.

The Cell and its Nucleus Nucleus (Control Center)

To power all its activities, the cell relies on tiny power plants called mitochondria. These organelles take nutrients from the food you eat and turn them into usable energy for your body.

Mitochondria: The Powerhouses Releasing Cellular Energy (ATP)
✏️ Worked example

Identify the primary functions of both the nucleus and the mitochondria in a typical animal cell.

  1. 1. Recall that the nucleus acts as the command center of the cell.
  2. 2. Associate the nucleus with genetic instructions, containing DNA which guides all of the cell's activities.
  3. 3. Recall that the mitochondria act as the powerhouses of the cell.
  4. 4. Associate the mitochondria with cellular respiration, converting nutrients from food into usable energy.
  5. 5. Conclude that the nucleus directs cell operations, while mitochondria provide the energy required to carry out those operations.
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