CELL TRANSPORT MECHANISM

Diffusion

_______ is the movement of molecules from an area of higher concentration to an area of lower concentration.

equilibrium

This natural phenomenon will continue until ___________ is achieved and the molecules are distributed equally in a system.

passive

Diffusion across a membrane is an example of _______ transport.

Facilitated diffusion

__________ _______ involves the movement of molecules across the membrane but with the aid of either channel or carrier proteins.

These molecules are usually those that cannot cross due to their molecular size or chemical nature.

concentration gradient

____________ ________ or the difference in its concentration across a semipermeable membrane.

concentration gradient

Remember that in all types of passive transport, it is just the _________ ________that serves as the driving force

Osmosis

_______ is the diffusion of water across a selectively permeable membrane from a region of high water concentration to one with lower water concentration.

Tonicity

______ refers to the relative concentration of solutes in fluids separated by a selectively permeable membrane.

• isotonic

• hypotonic

• hypertonic

The tonicity of a solution depends on its concentration of solutes:

isotonic

The tonicity of a solution depends on its concentration of solutes:

When solute concentrations are similar on both sides of a membrane, water molecules move at the same rate in both directions. Solutions of equal solute concentration are said to be _______

hypotonic

The tonicity of a solution depends on its concentration of solutes:

When the overall solute concentrations of the two fluids differ, the fluid with the lower concentration of solutes than inside the cell is said to be ________

turgor pressure.

The tonicity of a solution depends on its concentration of solutes:

The swelling of a plant cell, when placed in a hypotonic solution, creates _____ _______

hypertonic

The tonicity of a solution depends on its concentration of solutes:

A solution with higher solute concentration is referred to as a ________ (hyper, over) solution. It refers to a solution with a higher concentration of solute outside of the membrane which causes the water to move to that area.

plasmolysis

By contrast, when a plant cell is placed in a hypertonic solution, the plasma membrane pulls away from the cell wall as the large central vacuole loses water. This is called __________, which refers to the shrinking of the cytoplasm due to osmosis.

osmoregulation

For an animal to survive in a hypotonic or hypertonic environment, it must have a way to prevent excessive uptake or loss of water and regulate the solute concentration of its body fluids. This control of this water balance is called ____________.

Active transport

______ ________ is a cellular transport mechanism that involves the movement of molecules against their concentration gradient with energy expenditure.

adenosine triphosphate or ATP

For a certain molecule to be transported against the concentration gradient, it needs a carrier protein and an expenditure of energy. In this case, chemical energy, which is usually liberated from ______ ___________ __ ___

pumps

Proteins involved in active transport often are called _____, because they use energy to move a substance against its concentration gradient

carrier protein

For a certain molecule to be transported against the concentration gradient, it needs a ______ _______ and an expenditure of energy.

sodium-potassium pump

A type of pump, which is common in animal cells and that is associated with nerve and muscle cells, is called the ______ _______ ____. This pump moves sodium ions (Na +) to the outside of the cell and potassium ions (K + ) into the cell. Their transport is linked together through the same carrier protein

solute gradient

This bidirectional transport of three sodium and two potassium ions creates a _____ _________ across the plasma membrane.

calcium pump

The _______ ____ does not need binding to a second ion for the protein pump to return to its original shape. It simply binds to the calcium ions and pumps them out of the cell.

Facilitated transport

__________ ________ is the movement of molecules or ions down the concentration with the help of membrane transport proteins.

Glucose transporters are found at the base of the epithelial cells of the

ntestines. These are carriers that supply glucose molecules to the underlying

tissues and into the bloodstream.

vesicle

A _______ is a structure within or outside a cell, consisting of a cytoplasm and enclosed by a lipid bilayer. These are formed naturally during the process of secretion, uptake, and transport of molecules.

bulk or vesicular transport

Larger molecules that cannot be carried through transport proteins can be transported into and out of the cell through ____ __ _______ _________

1. budding

2. scission

3. uncoating

4. translocation

5. tethering

6. fusion

There are different processes involved in bulk transport which are:

• proteins

• polysaccharides

• nucleic acids

Molecules that can be transported through the process of bulk transport include:

• exocytosis

• endocytosis

Types of Vesicular Transport:

Exocytosis

Types of Vesicular Transport:

_________ is a process of transporting molecules outside the cell

endocytosis

Types of Vesicular Transport:

Another form of bulk transport is ________. In this process, a cell takes in large molecules in which a small part of the plasma membrane balloons inward taking in the molecules.

• Phagocytosis

• pinocytosis

There are two kinds of endocytosis:

phagocytosis

There are two kinds of endocytosis:

The first kind of endocytosis is known as “cell-eating” or _________. In this process, the cell engulfs a particle by wrapping extensions called pseudopodia around it then packs it within a vacuole.

pinocytosis

There are two kinds of endocytosis:

The other kind of endocytosis is called _________ which occurs when a vesicle forms around a liquid. The molecules inside it will be digested and absorbed into a cytosol.

receptor-mediated endocytosis

A special form of pinocytosis is called ___________________ _______, in which it enables a cell to acquire specific solutes. A specific receptor on the cell surface binds tightly to the macromolecule. The plasma membrane indents to form a coated pit that pinches closed to form a vesicle.

exocytosis

In the process of ________, an intracellular vesicle fuses with the plasma membrane as secretion occurs.

• Constitutive

• Regulated

Exocytosis can be of two forms namely:

Constitutive exocytosis

Exocytosis can be of two forms namely:

functions in transporting proteins like receptors that function in the plasma membrane.

Regulated exocytosis

Exocytosis can be of two forms namely:

is triggered when a cell receives a signal from outside.

endocytosis

In the process of ________, cells take in substances by forming vesicles that bud inward around the material. This type of transport can be of three forms namely: phagocytosis, pinocytosis, and receptor-mediated endocytosis.

• phagocytosis,

• pinocytosis

• receptor-mediated endocytosis

In the process of endocytosis, cells take in substances by forming vesicles that bud inward around the material. This type of transport can be of three forms namely:

phagocytosis

In the process of endocytosis, cells take in substances by forming vesicles that bud inward around the material. This type of transport can be of three forms namely:

In the process of __________, the cell engulfs the particle by wrapping around extensions called pseudopodia then packs it within a membrane-enclosed sac called vacuoles.

pseudopodia

In the process of phagocytosis, the cell engulfs the particle by wrapping around extensions called _________ then packs it within a membrane-enclosed sac called vacuoles.

pinocytosis

In the process of endocytosis, cells take in substances by forming vesicles that bud inward around the material. This type of transport can be of three forms namely:

The process of _________ occurs when vesicles form around a liquid or around very small particles.

receptor-mediated endocytosis

A form of pinocytosis known as ____ _________ _______ is quite specific because it uses a receptor protein to recognize compatible molecules which they bring into the cell.