A tour of the cell
A tour of the cell

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

A tour of the cell

4.12 Vacuoles

An organelle that is very prominent in all plant and fungal cells (but usually not in animal cells) is the vacuole (Figure 1b). Vacuoles can be very large and they have a number of roles. In mature plant cells, the vacuole is typically a membrane-bound space that fills most of the centre of the cell and is basically a storage compartment for water, ions and small organic molecules. In combination with the cell wall, vacuoles also have a role in determining the shape of the plant cell. A cell in which the vacuole is completely full of water is said to be turgid, and this cell turgidity ensures that the plant remains rigid and upright. In dry conditions, loss of cell turgidity results in plant wilting. Water molecules pass freely in and out of the vacuole, but the vacuolar membrane (the tonoplast) controls the passage of other molecules with specialised transporters that are different to those of the cell membrane. Vacuolar pH is lower than that of the cytosol, and vacuoles can contain enzymes that digest large organic molecules in a similar way to lysosomes in animal cells (lysosomes are rare in plant cells).

S294_1

Take your learning further371

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses372.

If you are new to university level study, we offer two introductory routes to our qualifications. Find out Where to take your learning next?373 You could either choose to start with an Access courses374or an open box module, which allows you to count your previous learning towards an Open University qualification.

Not ready for University study then browse over 1000 free courses on OpenLearn375 and sign up to our newsletter376 to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371