• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Cell Vacuole Essay

Extracts from this document...

Introduction

Cell Vacuole Essay Cell vacuoles are present in both animal cells and plant cells. Those found in animal cells are usually relatively small such as phagocytic vacuoles, food vacuoles, autophagic vacuoles and contractile vacuoles. Plants, however, have much larger cell vacuoles which are usually the largest structure in a plant cell often dominating the inside of the cell, crowding other organelles to the cell wall. The vacuole is bound by a very active membrane called the tonoplast. There are many different types of vacuoles, each with their own specialised functions. Here are examples of some common types of cell vacuoles: * Plant sap vacuole - present only in plants * Contractile vacuole * Food vacuole * Lysosomes * Pinocytic vesicles As mentioned earlier, the plant cell vacuole is surrounded by a membrane, the tonoplast. This membrane separates the cytoplasm from the vacuole and controls the exchange of substances between the vacuole and the cytoplasm. An important feature of plant vacuoles is its osmotic properties. These are responsible for a variety of essential processes that occur in plants including support by turgidity to water transport throughout the plant. It is to water transport via plant vacuoles to which we first turn to. The movement of water into and out of cells is based on the principle of osmosis where there is net movement of water molecules from an area of high water potential to an area of low water potential across a selectively permeable membrane. ...read more.

Middle

These compounds are usually waste products and secondary products of metabolism which are accumulated in the vacuole e.g. crystals of calcium oxalate have sometimes been observed in certain plant cell vacuoles. Secondary products of metabolism such as alkaloids and tannins are mainly responsible for the deterring of animals. Some waste materials produced and stored by plants are of use to humans. For example, latex, a milky liquid, from rubber tress contains chemicals needed for rubber synthesis. Latex from opium poppies contain alkaloids such as morphine from which heroin can be obtained. The importance of the plant cell vacuole and its association with osmosis has already by illustrated with the role of water transport. Nevertheless, osmosis also plays a vital role in the growth of the plant via its interaction with the cell vacuole. This process is called vacuolation whereby the cells elongate as their vacuoles absorb water. This is a very efficient method of growth as the cells become larger with minimal investment in new cytoplasm. As well as water transport and growth, the vacuole also provides support for the plant using the principle of osmosis. When the solution outside the plant cell has a higher water potential than the cell vacuole or a plant is well watered then water will enter the cell by osmosis. ...read more.

Conclusion

Besides helping to feed the cell, lysosomes play an important custodial role when cell components wear out. Lysosomal enzymes can degrade membranes, ribosomes, proteins and a variety of other components and the subunits can then be returned to the cytoplasm for reuse. In white blood cells they are used to digest bacteria. The head of a sperm contains a special lysosome which is used for digesting a path to the ovum. Sometimes, within injured or old cells, lysosomes also break open and free their enzymes, literally digesting the cell from the inside out. Another function of vacuoles, similar to phagocytosis, is pinocytosis. A good example of this is in capillaries where the membranes of cells that line capillaries pinch off vacuoles filled with yellowish, protein - rich blood serum, carry the fluid across the cytoplasm of the cell as a pinocytic vesicle, then expel it from the capillary. The discharge of the fluid vascuolar contents is often called reverse pinocytosis. by coupling pinocytosis and reverse pinocytosis, capillary cells can transport serum from the blood vessel to the surrounding tissue space without exposing the serum components to the cytoplasm, where it might be chemically damaged. Vacuoles play vital roles not just in plant but also in many other types of cells. Their functions range from providing a plant with support to digesting endocytotic materials. The diversity of their structure means that they are suited to an extensive and varied range of tasks. Sean Fang 12SD ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    Beetroot contains red pigments called betalains, located within the cell vacuole. Normally the pigments ...

    4 star(s)

    A membrane is a phospholipid bilayer studded with proteins, polysaccharides and other sorts of lipids. This patchwork of molecules is like a mosaic. Because the molecules move about within their respective layer, the membrane behaves like a fluid. This is why the model is called the Fluid-mosaic model.

  2. Liver and its role

    Figure 1.3 There are many factors affecting the enzyme activity, such as: > Temperature: According to kinetic theory, the higher the temperature the higher the kinetic energy of the molecules (substrates effectively), so they will vibrate faster. This increases the possibility of the collision between enzyme and substrate and forming of enzyme-substrate complex.

  1. Cells Essay.

    to the matrix in mitochondria and houses DNA, RNA, ribosomes, and different enzymes. Chloroplasts, however, contain a third membrane and are generally larger than mitochondria. The plant cell wall The cell wall is a complex matrix which surrounds a plant cell.

  2. Plant Metabolism.

    photosynthesis, C=0.5-0.6, together with the change in Rubisco control when light intensity was suddenly changed this indicates that the extent to which Rubisco limits photosynthesis clearly depends on the short-term conditions under which the flux is measured. Despite the high levels of regulation mentioned previously however, in ambient conditions the

  1. An experiment to find of the isotonic point of root vegetables cells in contents ...

    The above equation clearly states that increased pressure potential increases the water potential because Water potential= pressure potential + solute potential. At this concentration I expect the masses of the root vegetable to increase. Alternatively if the solution has a higher concentration than the root vegetable then by process known

  2. Investigating Osmosis.

    to pass through. Cell membranes will not allow larger molecules like Sucrose, Starch, protein, etc. to pass through. 2. A region of high concentration of water is either a very dilute solution of something like sucrose or pure water. In each case there is a lot of water: there is a high concentration of water.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work