3.6 Active Transport

If the concentration of the substance inside the cell is greater than the concentration in the extracellular fluid, the cell must use energy to move the substance.

Some active transport mechanisms move small-molecular weight material.

Cells need to remove and take in larger molecule and particles in addition to moving small ion and molecule.

Some cells are capable of covering entire unicellular organisms.
You might have believed that large particles need energy to be released from the cell.
A large particle can't pass through the cell's outer shell.

In living systems, concentration gradients are more complex than simple concentrations of a substance across a space.

The cells have higher concentrations of K+) and lower concentrations of Na+) than the fluid in which they are bathed.
In a living cell, the concentration and electrical gradient of Na+ causes the ion to diffuse into the cell, and the electrical gradient of Na+ causes the ion to go into the negatively charged interior.
The situation for other elements is more complicated.

Concentration and electrical gradients have an effect on chemical gradients.

The cell uses energy to move substances against a concentration.

The energy is generated through cellular metabolism.
The active transport mechanisms work against the gradients.
Small substances pass through the membranes.
Active transport maintains concentrations of ion and other substances needed by living cells.
A cell's supply of energy may be spent on maintaining processes.

Because active transport mechanisms depend on cellular metabolism for energy, they are sensitive to many metabolic poisons that interfere with the supply of ATP.

There are two mechanisms for the transport of small-molecular weight material.

A difference in charge is created by primary active transport.
At the same time, a second substance is moved out of the cell by the primary active transport system.
An important pump in animal cells, the sodium-potassium pump, uses energy to move potassium into the cell and a different number of sodium ion out of the cell.

Secondary active transport is the movement of material using the energy of the electrochemical gradient.

The energy created by the primary active transport system can be used to bring other substances into the cell.
Secondary active transport uses a hydrogen ion gradient in thechondrion.

There are different variations of endocytosis, all of which have the same characteristic: a pocket around the target particle.

The pocket pinches off, causing the particle to be contained in a new vacuole.

There are three variations of endocytosis.

The name literally means "cell drinking" and was given at a time when the assumption was that the cell was drinking.

This process takes in solutes that the A targeted variation of endocytosis uses to bind certain substances to the cell.
It will stay in those fluids and increase in concentration.

Some human diseases are caused by a failure of endocytosis.

The form of cholesterol referred to as "bad" cholesterol is removed from the blood by endocytosis.
There is a human genetic disease called familial hypercholesterolemia.
People with this condition have life-threatening levels of cholesterol in their blood, because their cells cannot clear the chemical from their blood.

The process of exocytosis is different from moving material into a cell.

There is a particle in the interior of the membranes.
The fusion opens the membranous envelope to the outside of the cell, and the particle is expelled into the extracellular space.

The contents of a vesicle are released to the outside of the cell.

The smallest unit of life is a cell.

Most cells are too small to be seen with the naked eye.
Scientists use microscopes to study cells.
Light microscopes provide less detail than electron microscopes.
The cell is the basic unit of life, new cells arise from existing cells, and all organisms are composed of one or more cells according to the unified cell theory.

The Prokaryotic and Eukaryotic Cells are mostly single-celled organisms.

All prokaryotes have some or all of the following.
Many of them have polysaccharide capsule.
The diameter of prokaryotic cells is between 0.1 and 5 um.

A eukaryotic cell is larger than a prokaryotic cell, has a true nucleus, and has some of the same functions as a prokaryotic cell.

The size of prokaryotic cells tends to be 10 to 100 times that of ekaaryotic cells.

A eukaryotic cell is larger than a prokaryotic cell, has a true nucleus, and has some of the same functions as a prokaryotic cell.

There is a bilayer embedded in the blood.
ribosome assembly takes place at the nucleolus within the nucleus.
The ribosomes are attached to the side of the reticulum.
They perform a task.
Mitochondria produce energy.
Some toxins are broken down by peroxisomes.
Vesicles and vacuoles are used for storage and transport.
vacuoles help break down macromolecules in plant cells.

The lysosomes and centrosome are found in animal cells.

The centrioles have an unknown role in cell division.
Animal cells have lysosomes.

Plants have a cell wall, a central vacuole, and a chloroplast.

The plant cell wall protects the cell, provides structural support, and gives shape to it.
The photosynthesis takes place in the cells of the body.
The central vacuole enlarges the cell without the need for more cytoplasm.

The nuclear envelope, the reticulum, Golgi apparatus, lysosomes, and vesicles are included in the endomembrane system.

The components work together to modify, package, tag, and transport.

There are three different types of protein elements.

Microfilaments give rigidity and shape to the cell.
The nucleus and other organs are in place.

Microtubules help the cell resist compression, serve as tracks for motor proteins that move vesicles through the cell, and pull replicated chromosomes to opposite ends of a dividing cell.

The structural elements of centrioles, flagella, and cilia are also referred to as the structural elements.

Animals communicate with each other through tight junctions, desmosomes, and gap junctions.

The plant cells communicate with each other.

The fluid mosaic model is referred to as the modern understanding of the plasma membrane.

The bilayer of phospholipids has their tails in contact with each other.
The landscape of the cell is made up of many different types of cells.
The materials are transported into or out of the cell.
Carbohydrates are attached to the outer surface of the cell.
The complexes identify the cell to other cells.
The fluid nature of the membranes is due to the configuration of the fatty acid tails, the presence of cholesterol in animal cells, and the mosaic nature of the proteins andcarbohydrate complexes, which are not firmly fixed in place.
The borders of cells are not static but are dynamic and constantly changing.

The forms of transport that move the material are passive.

When a substance is evenly distributed in a system, it diffuses from areas of high concentration to areas of low concentration.
Each type of molecule diffuses according to its own concentration.
Concentration, size of particles, and the temperature of the system are some of the factors that can affect the rate of diffusion.

The dispersal of substances into and out of cells is a function of the plasma membrane.

Some materials are easy to diffuse through the membranes, but others are hard to pass through.
Balance of the concentrations of the solutions that occur in the chemistry of living things is an ongoing problem.
In living systems, it would be difficult to get some substances to move.

Concentration and electrical gradient are included in the combined gradient that affects an ion.

Living cells need more substances in their concentrations than they do in the extracellular space.
It takes energy from the cell to move substances up their electrochemical gradients.
The transport uses energy stored in the ATP to fuel it.

The transport of small molecule-size material is accomplished by the use of integral proteins in the cell.

Some pumps carry out primary active transport and drive their action.
Energy from primary transport can be used to move another substance into the cell.

Cells can be engulfed by other cells in a process called phagocytosis if parts of them are used to fuel the transport of large particles.

In phagocytosis, a portion of the membrane invaginates and flows around the particle, eventually pinching off and leaving the particle wholly enclosed by an envelope of plasma membrane.
The particles used as food or dispatched in some other way are broken down by the cell.
On a small scale, pinocytosis is a similar process.
Wastes are moved outside the cell, pushing a membranous membranous vesicle to the plasma membrane, which in turn allows the membranous membranous to incorporate itself into the structure of the cell.

Isotonic saline solution is what structures think.

Scientists use special stains to distinguish high temperatures components of cells when viewing a specimen through a light microscope.

The basic unit of life is the ___________.

Water moves through water.

The main force driving movement is b. Mitochondrion.

Active transport has to function continuously.