Active transport Revision Notes

Active transport is the movement of particles such as ions or molecules through a cell membrane from an area of lower concentration to an area of higher concentration.

This movement is against the natural concentration gradient and cannot happen by diffusion alone.

• Particles move from low to high concentration.
• Movement is against the concentration gradient.
• Requires energy input.

Active transport requires energy because it moves particles against their natural gradient.

The energy comes from respiration inside the cell, which produces ATP.

Transport proteins in the membrane use this energy to carry particles across.

• Energy is needed for active transport.
• Energy comes from respiration (ATP).
• Transport proteins use this energy to move particles.

Active transport allows cells to absorb substances even when they are in lower concentration outside the cell.

This process helps maintain necessary concentrations of ions and nutrients inside cells for proper function.

• Allows uptake of essential substances against gradient.
• Maintains cell nutrient and ion balance.
• Supports cell survival and function.

Root hair cells absorb mineral ions such as nitrate and potassium from the soil, even when ion concentration is higher inside the cell than outside.

This absorption occurs by active transport, moving ions against their concentration gradient using energy.

• Ions are absorbed against concentration gradient.
• Active transport allows uptake when soil ion concentration is low.
• Essential for plant nutrition and growth.

Active transport requires energy, which is supplied by ATP produced during respiration.

Root hair cells contain many mitochondria to provide sufficient energy for active transport.

• Energy comes from respiration in mitochondria.
• Mitochondria produce ATP for active transport.
• High energy demand in root hair cells for ion uptake.

Without active transport, plants could not absorb enough mineral ions from the soil, especially when soil concentrations are low.

This would lead to mineral deficiencies and poor plant growth.

• Active transport ensures mineral ion uptake.
• Supports plant nutrition and health.
• Prevents mineral deficiency in plants.

Protein carriers are specialized proteins embedded in the cell membrane that facilitate active transport.

They bind to specific molecules or ions on one side of the membrane.

Using energy from ATP, they change shape to move these substances across the membrane against their concentration gradient.

• Protein carriers enable movement from low to high concentration.
• They are selective for particular molecules or ions.
• Energy input is essential for their function.

Active transport requires energy because substances move against their natural diffusion gradient.

ATP provides this energy by releasing phosphate groups that induce conformational changes in protein carriers.

Without ATP, protein carriers cannot transport molecules against the concentration gradient.

• ATP hydrolysis powers protein carrier shape changes.
• Energy use distinguishes active transport from passive processes.
• Cells use active transport to accumulate essential nutrients.

The protein carrier binds the molecule or ion on the side with lower concentration.

It then changes shape, transporting the molecule across the membrane.

Finally, the molecule is released on the side with higher concentration, and the carrier returns to its original shape to repeat the process.

• Binding is specific to the transported molecule or ion.
• Shape change is key to moving substances across membranes.
• The cycle repeats as long as energy is available.