2.5 Particle Movement in and out of Cells

Particle Movement into and out of Cells

Diffusion,
Facilitated Diffusion,
Active Transport

Building Design

Imagine being an architect and you are to design a building on a rural area. You have to think about where people should enter and exit, where the visitors should go, how cars can go to the garage, how the water lines can easily flow, the electric lines, how air can be filtered, and how you can keep out the large animals and large birds from coming in yet allow insects in to your mini garden.

Cells have various ways of letting substances in

• Passive Transport

• Active Transport

Passive Transport

this is movement of molecules from high concentration to low concentration-----this is like going down a slide

Passive does NOT require energy!

Active transport

this is the movement of molecules from low concentration to high concentration---this is like running up a slide in the opposite direction

Active requires energy!

Multiple Choice

What are the two main types of transport?

• active and passive

• osmosis and facilitated

Diffusion

Movement of molecules from high concentration to low concentration.

Stops when equilibrium is reached

Multiple Choice

How do molecules move during diffusion?

• From high concentration to low concentration

• From low concentration to high concentration

cell membrane = semi-permeable

​what is semi-permeable (selectively permeable)

The cell membrane allows some substances to pass in and out of the cell easily, but other substances cannot. Some substances require "helpers" such as protein channels to get through the cell membrane.

Match

Match the following

phospholipid

cell membrane proteins

phospholipid bilayer

• phospholipid

• cell membrane proteins

• phospholipid bilayer

Passive Transport

Passive transport is a movement of ions and other atomic or molecular substances across cell membranes without need of energy input. Unlike active transport, it does not require an input of cellular energy because it is instead driven by the tendency of the system to entropy or "go with the flow" (concentration gradient)

Passive Transport

There are three examples of passive transport:

1. simple diffusion

2. facilitated diffusion

3. osmosis

Simple Diffusion

As shown by the image on the right, diffusion shows how small substances can enter freely through the lipid bilayer. That is possible because the particles that can diffuse easily are SMALL, Electrically UNCHARGED particles like gases.

2. Osmosis

Facilitated Diffusion

As shown by the image on the right, it is the process of spontaneous passive transport of molecules or ions across a membrane via specific transmembrane integral proteins. (channel/carrier protein)

Glucose enters the cells through facilitated diffusion with the help of GluT.

Multiple Choice

When molecules move DOWN or ALONG the concentration gradient, it means it moves in what direction?

• high to low

• low to high

Multiple Choice

Is facilitated diffusion passive or active transport?

• passive

• active

Multiple Choice

When molecules spread from areas of high concentration, to areas of low concentration across the phospholipid bilayer, this if referred to as:

• simple diffusion

• facilitated diffusion

1. Facilitated Diffusion

•Facilitated Diffusion is the passive movement of polar or charged particles from an area of higher concentration to an area of lower concentration through a protein channel.
•Charged particles cannot easily diffuse through the phospholipid bilayer so they need passageways in the form of leak channels, or protein gates.

•Equilibrium is still achieved when the concentration of solutes (charged or particles) are even or have the same net movement inside and outside the membrane.

Multiple Choice

Which of the following DOES NOT properly describe PASSIVE transport?

• small non-polar substances can diffuse through the membrane

• no energy is used during diffusion by passive transport

• solutes diffuse towards where their concentration is high

• in hypotonic solution, diffusion of solutes is higher in going into the cell

OSMOSIS

It is the movement of a solvent across a semipermeable membrane toward a higher concentration of solute (lower concentration of solvent). In biological systems, the solvent is typically water, but osmosis can occur in other liquids, supercritical liquids, and even gases.

OSMOSIS

The image on the right shows how water moves from low concentration of solutes (sugar molecules) to high concentration of solutes. This movement caused a change in volume of the two sides of the container, with a semipermeable membrane dividing them.

Multiple Choice

Which of the following DOES NOT properly describe ACTIVE transport?

• it can move substances against concentration gradient

• it moves substances from high concentration to low concentration of solutes

• it can switch the positions of two kinds of solutes by using energy (across the membrane)

• it can move chemically charged particles (across the membrane)

Turgor Pressure

Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called hydrostatic pressure.

Flaccid vs Turgid

With the presence of cell wall, plants tend to have better health and metabolic processes when they can store more water. In hypotonic conditions, plants tend to look healthy and well, while in isotonic conditions, plants turn flaccid, soft, and hanging loosely.

consider the properties required to enter the plasma membrane

Multiple Choice

Osmosis transport...

• solutes from high concentration to low concentration

• water molecules from dilute to concentrated solutions

• water molecules from high concentration to low concentration of solutes

Multiple Choice

Simple diffusion allows the movement of _________ across the membrane.

• small polar substances

• small non-polar substances

Multiple Choice

What do you call the protein channels that specifically lets water enter and exit the cell membrane?

• hydroponics

• aquaporins

• plasmodesmata

Multiple Choice

When water moves from region A to region B...

• it means region B has a high concentration of solutes

• it means region B has a high concentration of water

• it means water can diffuse through the phospholipid bilayer

• it means region A has lower concentration of solutes

Multiple Choice

Cells in isotonic solution...

• have water's net movement virtually at zero; there is equal movement going in and out of the cell.

• have water's net movement favor its ENTRY to the cell, hence the cell swells.

• have water's net movement favor its OUT of the cell, hence the cell shrinks.

Multiple Choice

Which kind of solution is best for plant cells?

• isotonic

• hypotonic

• hypertonic

Multiple Choice

Which solution causes animal cells to burst?

• isotonic

• hypotonic

• hypertonic

Multiple Choice

Which solution causes animal cells to burst?

• isotonic

• hypotonic

• hypertonic

Multiple Choice

A plant cell in a hypertonic solution will

• burst

• plasmolyze

• become turgid

Multiple Choice

An animal cell in a hypertonic solution will

• become flaccid

• lyse

• shrivel

Active Transport

Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement.

Active Transport

Active transport comes in 3 kinds:

1. Endocytosis - can come in the form of phago or pinocytosis

2. Exocytosis

3. Protein Pump

What do you notice about the structures of these three?

Recall that the phospholipids can orient themselves based on where water is located.

Liposome

A liposome is a spherical-shaped vesicle that is composed of at least one phospholipid bilayer with an aqueous core. Liposomes closely resembles the structure of cell membranes. They are also very useful drug delivery system.

Micelle

Micelles are closed lipid monolayers with a fatty acid core and polar surface, or polar core with fatty acids on the surface (inverted micelle).

The phospholipid bilayer can reorient itself into liposomes and micelles.

When cells need to bring a very large substance into or out of the cell that cannot fit into the protein channels, these large substances are passed on through micelles (for non-polar/ oil-based substances) and liposomes (for polar substances) and then pinches off.

Multiple Choice

Where is there a low concentration of dye?

• at the bottom of cup
• in the color
• at the top of cup 
• no concentration gradient

Multiple Choice

What is the term that means "a condition in which the concentration of a substance is equal throughout a space"?

• equilibrium
• exocytosis
• endocytosis
• phospholipid

Multiple Choice

In this image, the cell is using which type of molecular transport?

• Osmosis
• Diffusion 
• Endocytosis
• Exocytosis 

Multiple Choice

Endocytosis is defined as

• the movement of large molecules from the inside of the cell to the outisde of the cell using channel proteins. 
• the movement of large molecules from the inside of the cell to the outisde of the cell membrane vesciles. 
•  the movement of large molecules from the outside of the cell to the inside of the cell using membrane vesciles.
• the movement of large molecules from the outside of the cell to the inside of the cell using channel proteins. 

Multiple Choice

A person with swollen gums rinses his mouth with warm salt water, and the swelling decreases. Which of the following has occurred?

• The swollen gums have absorbed the saltwater solution.
• The saltwater solution lowers the temperature of the water in the gums.
• The salt in the solution has moved against the concentration gradient.
• The water in the gums has moved out due to the high concentration of salt in the solution. 

Multiple Choice

Which illustration of transport across the membrane requires energy?

• A
• B
• C
• D

Multiple Choice

In this situation, where the solute is illustrated by red dots, predict if will WATER move into or out of the cell, and how that will affect the cell.

• Water will move into the cell and the cell will expand.
• Water will move into the cell and the cell will shrink.
• Water will move out of the cell and the cell will expand.
• Water will move out of the cell and the cell will shrink.

Multiple Choice

Which means of particle transport is shown in this diagram?

• endocytosis
• exocytosis
• facilitated diffusion
• protein pump

Multiple Choice

Which of the following is correct about the Golgi? 

• Digests waste materials 
• Protection and Support 
• Modifies and packages molecules 
• cellular movement 

Multiple Choice

What is an isotonic solution?

• When solutions are in equilibrium 
• When the solution has more solute 
• When the solution has less solute 
• Has a greater pressure 

Multiple Choice

What is facilitated diffusion?

• Transport that uses proteins to help move molecules across the membrane. 
• Movements of substances through a membrane. 
• When molecules spread from High to Low concentration on their own. 
• When pressure pushes something through a membrane. 

Multiple Choice

What organelle of the cell produces energy?

• Mitochondria 
• Golgi Body 
• Vesicle 
• Vacuole 

Multiple Choice

Which diagram best shows the end result of diffusion?

• F
• G
• H
• J

Multiple Choice

Active transport requires ______, moves materials from __________________, and goes _______ the concentration gradient.

• No energy, low to high, against
• ATP, high to low, with
• ATP, low to high, with
• ATP, low to high, against

Multiple Choice

The picture below is an example of _________________.

• osmosis
• isotonic
• diffusion
• active transport

Multiple Choice

What is the difference between active and passive transport?

• Active does not need energy and passive uses ATP (energy)
• Active uses ATP (energy) and passive does not need energy
• Active stores transport proteins and passive releases 
• Active uses hormones and passive does not 

Multiple Choice

The sodium-potassium pump usually pumps

• only potassium ions and sugar molecules
• potassium ions out of the cell
• sodium ions into the cell
•  potassium ions into the cell

Multiple Choice

The sodium potassium pump usually pumps

• potassium out of the cell 
• sodium out of the cell 
• sodium into the cell 
• both potassium and sodium into the cell