How Turgor Pressure Supports Plant Cells and Growth
In plants, turgor is also known as hydrostatic pressure or water potential or turgor pressure. Hydrostatic pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is a kind of pressure which is produced due to water. It occurs only in a plant cell.
When water moves inside the cell, then it develops a pressure inside the cell wall, that pressure is especially called turgor pressure. The role of turgor pressure is to push the cell wall outward by pushing water inside the cell wall outward so that the cell wall exists in its proper shape.
How do the Plants maintain their Turgor Pressure?
Inside the plant cell, there is a vacuole organelle which is also called anima vacuole, which is in between cell membranes. Water is stored in the vacuole which pushes against the cell wall which produces pressure in the cell membrane; that pressure is called turgor pressure. Without turgor pressure, the plant will wilt.
It is also called hydrostatic pressure because plants need fluid to maintain pressure caused by pushing against the cell wall.
Role of Large Vacuoles in Plants
The vacuole is generally present in a plant cell only, which is almost filled with water. Vacuoles are majorly responsible for maintaining the turgor pressure within the cell. It also helps in removing the harmful waste products from the cell. Vacuoles contain small molecules which manage the acidic internal pH. Vacuoles are bounded by a single membrane, and this vacuole works as a combination of works, especially keeping the cell in shape.
Mechanism
A. Flaccid Cell:
The flaccid cell is also known as a shrink cell. The Turgor pressure of the flaccid cell is zero. As we know that, DPD (diffusion pressure deficit) is equal to osmotic pressure subtraction of turgor pressure.
DPD (diffusion pressure deficit) = OP(osmotic pressure) - TP (turgor pressure)
When the value of turgor pressure in a shrink cell is zero, it means the value of DPD is equal to osmotic pressure. So, it is important that the value of the flaccid cell is equivalent to the osmotic cell.
B. Turgid Cell:
In a turgid cell, turgor pressure is equivalent to the osmotic cell, then the DPD value of the turgid cell becomes zero.
In animal cells, the turgor pressure process is not found in animal cells because there are only plasma membranes present in animal cells with no cell wall. If there is too much pressure occupied by the inner content of the cell, it may be possible that the cell gets burst. So that's why turgor pressure is not found in animal cells.
Significance of Turgor Pressure
Let’s develop two cell systems that represent the plant cell, system A or system B.
In system A, cells are tightly intact with each other with zero space like brick walls, while another system B cells are loosely packed with space.
If we consider the turgor pressure of this system A cells, the water concentration of this cell has more than system B which has high turgor pressure in the cell.
Cells of system B are comparatively flaccid, which means the turgor pressure of these cells is low.
High turgor pressure in plant cells leads to proper shape which means the body of the plant will be in a good position, whereas low turgor pressure will make cells shrink toward inwards (cell wall is silently flexible) which make voids between the cells which is known as intracellular space.
When intracellular space is developed, the plant cell will wilt which results in the plant to grow wilted. That is why plants need proper amounts of water to grow healthily. Thus, this is the importance of turgor pressure. Turgor pressure is caused by the osmotic flow of water and occurs in plants, fungi and bacteria.
Wall Pressure
Wall pressure is totally opposite to the turgor pressure. It means pressure on the content of the cell wall. It works opposite the cell wall.
FAQs on What Is Turgor in Biology?
1. What exactly is turgor in biology?
In simple terms, turgor is the state of a plant cell being swollen and firm due to the pressure of water inside it. Think of a fully inflated balloon; the air pressure pushing against the balloon's skin is similar to the turgor pressure a plant cell's contents exert on its cell wall.
2. Why is turgor pressure so important for plants?
Turgor pressure is vital for several reasons, as it helps plants to:
- Maintain the rigidity and shape of their cells, which keeps stems upright and leaves spread out to catch sunlight.
- Support non-woody plant parts, preventing them from wilting.
- Drive processes like the opening and closing of stomata, which are tiny pores essential for gas exchange.
- Facilitate cell growth and expansion.
3. What is the difference between turgor pressure and wall pressure?
They are two opposing forces that balance each other. Turgor pressure is the outward pressure exerted by the fluid inside the cell pushing against the cell wall. In response, the rigid cell wall exerts an equal and opposite inward pressure called wall pressure. This prevents the cell from bursting.
4. Can you give a real-world example of turgor?
A perfect example is the difference between fresh and wilted lettuce. A crisp lettuce leaf is full of water, so its cells are turgid and firm. When the lettuce wilts, it's because the cells have lost water, leading to a loss of turgor pressure, which makes the leaves soft and droopy.
5. What happens to a plant cell when it loses turgor?
When a plant cell loses turgor due to water loss, it becomes flaccid (limp). The cell membrane pulls away from the cell wall, a process known as plasmolysis. On a larger scale, this loss of turgidity across many cells is what causes a plant to wilt.
6. How does turgor relate to the concept of dehydration in humans?
While humans don't have turgor pressure like plants, the term 'turgor' is used to describe skin elasticity, which helps assess dehydration. A skin turgor test involves gently pinching the skin. In a well-hydrated person, the skin snaps back quickly. In a dehydrated person, the skin loses elasticity and returns to normal slowly, indicating poor turgor.
7. If turgor pressure is so strong, why don't plant cells burst when they absorb a lot of water?
Plant cells don't burst because of their strong, semi-rigid cell wall. Unlike an animal cell, which would rupture (a process called lysis) in pure water, the plant's cell wall provides structural support. It pushes back against the internal turgor pressure, creating a stable, turgid state without breaking the cell.
