Movement across membrane ( Active Transport)

Active Transport

The movement of substances against their concentration gradient from a low to high concentration of that substance across the membrane.

Using ATP and protein carriers

What is a carrier protein ?

These membrane have a regions. That binds to and allows the hydrolysis of a molecule of ATP to release energy = acts as enzyme.

Have specific regions that combine reversibly with only certain solutes molecules/ ions.

The energy helps the carrier protein change its conformation. ~ carry the ion from one side of the membrane to other.

Why is active transport important ?

Kidney : Reabsorption of sugar + ions from the venal filtrate

Nerve Cells : The Na + : K + pump maintain the resting potential

Phloem : loading os sucrose for transport

Bulk Transport

Movement of large quantities of material :

into cell endocytosis out of the cell exocytosis using vesicles

What does endocytosis involve taking of ?

Solids : Phagocytosis / Cell eating / Specialized cell or phagocytes ( WBC + Amoeba )

Liquids : Pinocytosis / Human egg

Bulk Transport - Exocytosis

Movement of large quantities of material out of the cell

This happens in :

• Secretory cells : Glandular cell in gut / breast

• In phagocytes : after the contents of the phagocytic vesicle have been digested

• Plant cells : during cell wall building

Phagocytosis

Bulk Transport of solids : It takes place in specialized cell * Phagocytes *

• Neutrophils are phagocytes white blood cells

• Ingest / engulf bacteria as part of body’s defense system

• Amoeba

How does bulk transport work ( Phagocytosis )

1) The membrane extends ‘ arms ‘ ( pseudopadia ) around the particle / pathogen which it wants to dissolve.

2) Once the membrane has fully engulfed the particle, it buds off creating a vesicle inside the cell.

3) The vesicle will usually fuses with lysosomes, and its; content will be dissolve / digested.

Bulk Transport - Pinocytosis

Bulk Transport of Liquid : cell drinking

If the vesicles pinched off are very small called micro pinocytosis *

The human egg cell ( ovum ) take up the nutrients by pinocytosis from the collide cell that surround it.