[Biology Class Notes] on Turgor Pdf for Exam

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.