Cell Movements

Selectively permeable

A cell membrane is ___, it allows some substances, but not others, to pass into or out of the cell

1. Enzymes

2. Glycogen

3. Potassium Ions

These substances are found in greater concentrations inside the cell

1. Sodium Ion

2. Calcium Ion

3. Chloride Ion

These substances are found in greater concentrations inside the extracellular fluid

Passive Membrane Transport

This type of transport does not require the cell to expend energy

Active Membrane Transport

This type of transport requires the cell to expend energy, usually in the form of ATP

1. Diffusion

2. Osmosis

3. Facilitated Diffusion

3 Types of Passive Membrane Transport Mechanism

1. Active Transport

2. Secondary Active Transport

3. Endocytosis

4. Exocytosis

4 Types of Active Membrane Transport Mechanism

Diffusion

A process where each solute tends to move from an area where it is in higher concentration to an area where it is in lower concentration in solution

Solution

It is generally composed of two major parts, solutes and the solvent

Solute and Solvent

___ are substances dissolved in a predominant liquid or gas, which is called the ___

Solutes

They are in constant motion

Diffusion

It results from the natural, constant random motion of all solutes in a solution

Concentration Gradient

It is the difference in the concentration of a solute in a solvent between two points divided by the distance between the two points

Large, Small

The concentration gradient is said to be steeper when the concentration difference is ___ and/or the distance is ___

Diffusion

It is an important means of transporting substances through the extracellular fluid and cytoplasm

Osmosis

It refers to the movement of water (when it is a solvent in a solution)

Osmosis

It is the diffusion of water across a selectively permeable membrane, such as the cell membrane, from a region of higher water concentration to one of lower water concentration

Phospholipid molecules, water channels

In osmosis, the water passes by either between the ___ or through ___

Osmosis

Where water diffuses from a solution with higher water concentration across the cell membrane into a solution with a lower water concentration

Osmotic Pressure

It is the force required to prevent the movement of water across a selectively permeable membrane

Osmotic Pressure

It is a measure of the tendency of water to move by osmosis across a selectively permeable membrane

Hypotonic

A solution that has a lower concentration of solutes and a higher concentration of water relative to the cytoplasm of the cell

Lysis

A process where the cell swells and ruptures

Isotonic

A solution where the concentrations of various solutes and water are the same on both sides of the cell membrane

Hypertonic

A solution that has a higher concentration of solutes and a lower concentration of water relative to the cytoplasm of the cell

Crenation

Refers to cell shrinkage

Facilitated Diffusion

It is a mediated transport process, involving membrane proteins such as channels or carrier proteins, to move substance across the cell membrane

Cell Membrane Channels

It consists of large protein molecules that extend from one surface of cell membranes to the other

1. Size

2. Shape

3. Charge

Characteristics for ion or molecule to pass through a channel

1. Leak Channels

2. Gated Channels

2 Classes of Cell Membrane Channels

Leak Channels

This channel constantly allows ions to pass through

Gated Channels

This channel limits the movement of ions across the membrane by opening and closing

Carrier Molecules

These are proteins within the cell membrane that are also involved in facilitated diffusion

Carrier Molecules

It can move water-soluble molecules or electrically charged ions across the cell membrane

Specificity

Similar to channels, carrier molecules exhibits ___ (ex: glucose carrier molecules move glucose across the membrane)

Active Membrane Transport

It is a process that utilizes membrane proteins to move substances across the cell membrane from regions of lower concentration to those of higher concentration, against a concentration gradient

Active Membrane Transport

This type of transport requires energy in the form of ATP

Sodium-potassium Pump

It moves Sodium (Na+) out of the cells and Potassium (K+) into cells (higher concentration of Na+ outside the cell and a higher concentration of K+ inside the cell)

Secondary Active Transport

It involves the active transport of one substance, such as Na+, across the cell membrane, establishing a concentration gradient, which the provides the energy for moving a second substance across the membrane

Cotransport

The diffusing substance moves in the same direction as the transported substance

Countertransport

The diffusing substance moves in a direction opposite to that of the transported substance

Vesicles

Membrane-bound sacs where large water-soluble molecules that cannot be transported by carrier molecules, small pieces of matter, and even whole cells can be transported across cell membranes

Endocytosis

It is the uptake of material through the cell membrane by the formation of a vesicle

Cell membrane (Endocytosis)

It invaginates (folds forward) to form a vesicle containing the material to be taken into the cell, it then moves into the cytoplasm

Receptor-mediated Endocytosis

Endocytosis usually exhibits specificity, through the process of ___