Lesson 9 Multicellular Organisms
Completion requirements
Specialized Cells
In order to be specialized, cells only use certain parts of their genetic code.
A9.15
Sieve tube cells
Each cell has the exact same DNA as every other cell in that organism; however, it will only use the parts of the DNA that it needs to perform the function assigned to it. Once a cell has become specialized, it will only perform the functions needed
to play its part in the tissue it is part of.
Just like each system has tissues that make it up, each tissue has specialized cells. For example, the phloem contains specialized cells called sieve tube cells. These cells can survive with their cytoplasm extending out past the boundaries of the cell. This allows the sieve tube cells to pass the sugars the phloem is transporting from one cell to the next. All plant cells have the DNA that codes for this function, but only sieve tube cells use this part of the DNA.
Just like each system has tissues that make it up, each tissue has specialized cells. For example, the phloem contains specialized cells called sieve tube cells. These cells can survive with their cytoplasm extending out past the boundaries of the cell. This allows the sieve tube cells to pass the sugars the phloem is transporting from one cell to the next. All plant cells have the DNA that codes for this function, but only sieve tube cells use this part of the DNA.
Another example is the growth of root hairs
on dermal tissue cells in the root system. The growth of these root hairs increases the surface area of these cells and allows them to absorb more water and dissolved minerals than they otherwise would be able to.
A9.16 Root hairs on a chilli pepper root
Did You Know?
A9.17 Herbal medicine
Before the development of western science and medicine, many cultures used plants for medicine, food, shelter, and clothing. Many Indigenous cultures saw and continue to see plants as sacred due to their importance in society. In western medicine, plants are often the basis of many drugs.
Watch This
Specialized Plant Cells © YouTube Donna Forward
This video gives a quick overview of some examples of specialized cells in plants. You will learn about these cells in more detail in the following lessons. This video also gives you microscopic images of the cells.
Read This
Please read pages 301 and 302 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the examples of specialization in plants. Remember, if you have any questions or you do not understand something,
ask your teacher!
Practice Questions
Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses
(where necessary) to study from.
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Why are specialized cells important in multicellular organisms?
Specialized cells allow each cell to have a single function to focus on. This allows the body to build systems and allows the organism to grow much larger than a single cell size. If cells were not specialized, the cells could not work together to form the systems needed for multicellular organisms.
- What is one example of a specialized cell?
You may think of other examples but here are a few:
- sieve tube cells—specialized for transporting sugars
- root hairs—specialized for absorption
- small intestine cells—specialized for absorption
- xylem cells—specialized for transporting water
- red blood cell—specialized for transporting oxygen