Cell Transport: Definition, Active, Passive, Endocytosis & Exocytosis

Cell Transport: Definition, Active, Passive, Endocytosis & Exocytosis – On this occasion we will discuss cell transportation. Want to know more details? see the discussion below in full.

The transportation system in living things is the process of transporting a compound or molecule from origin to a destination that occurs in cells. The transport system consists of two, namely passive transport and active transport.

Cell Transport: Definition, Active, Passive, Endocytosis & Exocytosis

Cell transport is divided into two types, namely:

Active Transport

Active transport is the transport of cells from low concentrations (hypotonic) to high concentrations (hypertonic) by requiring energy in the form of adenosine. triphosphate (ATP) from inside the cell and enzymes to work against the concentration gradient (the difference in concentration between two solutions), so that the cell can pass through the cell membrane cell.

Active transport can help maintain the balance of molecules in the cell. Enzymes will bind ions and transport ions from one side of the membrane to the other side of the membrane.

Active transport requires energy to regulate the entry and exit of ions and molecules through the cell membrane. Active transport is influenced by the electric charge contained inside and outside the cell. The electric charge is determined by sodium, potassium and chlorine ions.

The following six stages of active transport occur in the cell membrane:

1. Three sodium ions are taken from inside the cell and occupy binding sites (places where ionic or molecular bonds occur in the cell membrane).
2. Changing the shape of the integral protein in the membrane so that it opens to the outside of the cell with the help of energy.
3. Integral proteins in the membrane open to the outside of the cell, then release sodium ions out of the cell.
4. Two potassium ions from outside the cell enter and occupy the binding sites of integral proteins on the membrane.
5. Integral proteins in the membrane return to their original shape, that is, they open towards the inside of the cell.
6. Potassium ions are released into the cell.

Active transport is divided into two mechanisms, namely:

Primary Active Transport

Primary active transport is an active transport mechanism that requires energy in the form of ATP and enzymes directly to move molecules or ions from a low concentration to a high concentration and bring the molecules against the concentration gradient, resulting in a potential membrane.

Secondary Active Transport

Secondary active transport is a mechanism that uses energy periodically to move molecules against a concentration gradient.

Secondary active transport is divided into two types, namely:

• Secondary active transport co-transport is a secondary active transport mechanism when channeling occurs amino acid molecules and glucose by using a special protein and entered together with sodium ions inside cell. The amino acid and glucose molecules enter by using some of the energy from sodium transport which is primary active transport.
• Secondary active transport counter transport is a secondary active transport mechanism that takes place by exchange particles, such as at the same time that sodium ion molecules enter the cell there are other molecules that come out of the inside cell. In this case, active secondary counter transport plays a role in regulating pH levels in cells.

Passive Transport

Passive transport is cell transport that does not require energy and occurs directly without changing the direction of the concentration gradient.

Passive Transport is divided into two types namely Diffusion and Facilitated Diffusion:

Diffusion

Diffusion is the random movement of molecules from a high concentration (hypertonic) to a lower concentration (hypotonic). Substances involved in the diffusion process can be solid, liquid and gas. The diffusion process aims to achieve a concentration balance between the solute and the solvent.

Factors that affect the speed of the diffusion process, among others:

1. Form

The greater the bonds between molecules (the denser), the longer the diffusion process takes.

2. Temperature

The higher the temperature, the faster the intermolecular bonds are broken, so that the diffusion process takes place faster.

3. Molecular Size

The smaller the size of the molecules that cross a membrane, the easier it is for the diffusion process to take place at the same temperature when compared to larger molecules.

4. Concentration

The greater the concentration difference between the solute and the solvent, the greater the diffusion process.

Facilitated Diffusion

Facilitated diffusion is a cell transport mechanism assisted by certain proteins in the plasma membrane. These proteins form channels through which molecules can enter the plasma membrane.

Of these proteins there is a carrier protein, which is a protein that binds to a molecule, so that it can cross the plasma membrane.

Osmosis

Osmosis is the random movement of a solvent (water) from a low concentration to a high concentration so that water molecules can pass through a semipermeable membrane. An instrument for measuring osmotic pressure is called an osmometer.

• If the cell is in a high concentration environment, the cell will shrink because water will move out of the cell by osmosis.
• If the cell is in a low concentration environment, the cell will expand because it absorbs a lot of water because water osmosis from the environment and enters the cell.
• If plant cells are in a low concentration environment, turgor pressure will occur (pressure from inside the vacuole against the plasma membrane and cell wall due to inward osmosis of water vacuole). If a plant cell is in a high concentration environment, plasmolysis will occur (the release of the plasma membrane from the cell wall in plant cells).

Endocytosis

Endocytosis is the process of entry of particles into a cell. The membrane will form an indentation when the particles are pushed in and will form a vesicle (a space in the cell surrounded by the cell membrane) after the particles have passed through it.

Particles in the form of nutrients will directly enter the cell, while particles in the form of foreign substances will be directly digested by lysosomes with the help of digestive enzymes.

Endocytosis is divided into three types, namely:

• Phagocytosis

Phagocytosis is the process of ingesting/eating particles that occurs in leukocytes (white blood cells) and amoebae. The membrane will form indentations which will engulf the particles. Particles that are enveloped in the membrane will form vesicles and will escape to go into the cell.

• Pinocytosis

Pinocytosis is a cell mechanism by forming membrane indentations because the concentration of certain proteins and ions in the medium around the cell corresponds to the concentration inside the cell. The process of pinocytosis occurs in leukocytes, intestinal epithelium, liver macrophage cells and others.

The receptor attaches to the plasma membrane, resulting in an invagination (indentation) in the cytoplasmic membrane. The indentation gradually deepens into the cytoplasm, forming a pocket in the cytoplasm and a pinocytic duct.

When the sac detaches from the plasma membrane and forms pinocytosis bubbles, the bubbles will carry out fragmentation, until it shrinks and breaks into smaller bubbles which then merge into larger bubbles big.

• Facilitated Pinocytosis

In facilitated pinocytosis, the small pinocytotic bubbles that form due to fragmentation will leaves the surface of the membrane and the vesicle binds to the co-formed carrier protein vesicle.

Exocytosis

Exocytosis is the process of releasing/secreting particles/secretions wrapped in a bag/vacuole from in the cell because the vesicles (bubbles filled with serum fluids/molecules) bind/join the membrane plasma. Transport vesicles (bubbles for circulating substances/particles) that are released from the Golgi apparatus will be transferred by the cytoskeleton to the plasma membrane.

One of the roles of the plasma membrane in the cell is as a gateway for the passage of substances from and into the cell. More and more substances are constantly passing through the cell membrane causing traffic to occur.

Many secretory cells use exocytosis to transport (secrete) the products produced by these secretory cells. For example, beta cells in the pancreas produce insulin which is sent to the bloodstream by exocytosis.

Thus our discussion this time about Cell Transport: Definition, Active, Passive, Endocytosis & Exocytosis, I hope this article can add information to all of us, more or less apologize. Thank You.