Movement of Substances across the Plasma Membrane: Active Transport

Active Transport

Do you still remember the previous lesson???

Passive transport??

Simple diffusion ?Facilitated diffusion ?Osmosis ?

Active Transport

What is it ?

Active Transport

Movement of molecules or ions across the plasma membrane from a region of lower concentration to a region of higher concentration with the help of carrier protein and use ATP energy.

The molecules move against the concentration gradient

Mechanism of active transport

activity

Fill in the blanks. Refer to the

diagram.

Mechanism of active transport

1. The molecule binds to an active site of carrier protein.

2. Binding of the molecule to the carrier protein causes an ATP to bind to the other active site on carrier protein.

3. The carrier protein changes shape when the phosphate group bind to it.

4. Carrier protein moves the molecule across the membrane and releases the molecule

Mechanism of active transport

Mechanism of active transport

1. The molecule binds to an active site of carrier protein.

2. Binding of the molecule to the carrier protein causes an ATP to bind to other active site on carrier protein.

3. The carrier protein changes shape when the phosphate group bind to it.

4. Carrier protein moves the molecule across the membrane and releases the molecule

The process of passive and active transport in living

organisms

activity

Group discussion

How does gaseous exchange occur at the alveoli and blood capillaries?How do root hairs of a plant absorb water and ion?

How food is absorbed in the villi of the small intestine?

How gaseous exchange occurs in the alveoli and blood capillaries

Diffusion occurs when molecules move from an area of high concentration (of that molecule) to an area of low concentration

The blood in the capillaries surrounding the alveoli has a lower oxygen concentration of oxygen than the air in the alveoli which has just been inhaled

Both alveoli and capillaries have walls which are only one cell thick and allow gases to diffuse across them.

The same happens with carbon dioxide (CO2). The blood in the surrounding capillaries has a higher concentration of CO2 than the inspired air due to it being a waste product of energy production. Therefore CO2 diffuses the other way, from the capillaries, into the alveoli where it can then be exhaled.

Absorption of water by root hairs

Plants lose water by the process of transpiration, and water is used in metabolic processes by the plant. So, concentration of water molecules are very low in plant cell compared to the concentration of water molecule in the soil. Therefore, water molecules move into the cell through OSMOSIS.Water molecules moves down the concentration gradient.

Uptake of ions by root hairThe concentration of ions inside the root hair is greater than that in the soil solution. The uptake of mineral ions is therefore against the concentration gradient and, as a result, requires ACTIVE TRANSPORT. This is achieved using carrier proteins (in the cell membrane) and use ATP to provide energy to transport particular ions from the soil solution, where they are in low concentrations, into the root hair cytoplasm and vacuole, where they are in higher concentrations

Uptake of ion

• Anything that interferes with the metabolism of root hairs interferes with mineral absorption.

• http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/Roots.html

Process of glucose absorption in the villi

Concentration of glucose molecules in the lumen is higher than glucose molecules in the villi.However, glucose is a large water soluble molecules.Therefore, glucose molecules are transported across the membrane by facilitated diffusion with the help of carrier protein.

Glucose molecule binds to the binding site of a carrier protein.

Carrier protein changes it shapes to allow the molecules to pass through the membrane into the cell & return to its original shape.

After assisting the movement of the glucose molecules, it is able to assist the other glucose molecules to pass through the membrane until a dynamic equilibrium is achieved.

Processes in living organisms

Name the transport involves in following processes

activity

Exchange of gases during photosynthesis and respiration

Simple diffusion

Absorption of vitamin A,D,E and K by the villi

Simple diffusion

Absorption of glucose & amino acid in the villi

Facilitated diffusion

Absorption of water by root hairs of plant

Osmosis

Reabsorption of water by kidney tubules

Osmosis

Exchange of oxygen and carbon dioxide at the alveolus

Simple diffusion

Uptake of minerals by the root hairs of plant

Active transport

Transport of potassium ion into the nerve cell and excretion of sodium ion to the outside

Active transport

Uptake of oxygen by unicellular organisms

Simple diffusion

activity

COMPARISON BETWEEN PASSIVE & ACTIVE TRANSPORT

PASSIVETRANSPORT

SIMILARITIES ACTIVETRANSPORT

DIFFERENCES

Concentration gradient

Cellular energy

Outcome of the process

Occurs in

Name of process

Examples

PASSIVETRANSPORT

SIMILARITIES ACTIVETRANSPORT

•Transport of substances across the plasma membrane•Need a difference of concentration gradient between

extracellular environment & the cell

DIFFERENCES

Follow Concentration gradient

Against

Does not need energy

Cellular energy Need energy

Until an equilibrium is reached

Outcome of the process

Depends on the cells requirement (no need to reach an

equilibrium)

Non-living & living organisms

Occurs in Living organisms only

Simple diffusion, osmosis, facilitated

diffusion

Name of process Active transport

Examples

assessment

1. Active transport helps ______ to across the membrane

A. Amino acid

B. Glucose

C. Chloride ion

D. Potassium ion

2. In active transport, molecules across the membrane with the help of _______ and use ______.

A. Carrier protein, ATP energy

B. Carrier protein, ADP energy

C. Channel protein, ATP energy

D. Channel protein, ADP energy

3. In active transport, molecules across the membrane _______ the concentration gradient.

A. Against

B. Follow

4. Villi at the small intestine absorb glucose through _______

A. Active transport

B. Simple diffusion

C. Facilitated diffusion

D. Osmosis

5. Root hairs take in potassium ion by the process of ______

A. Active transport

B. Simple diffusion

C. Facilitated diffusion

D. Osmosis

6. Gaseous exchanges at the alveoli and blood capillaries occur through _______

A. Active transport

B. Simple diffusion

C. Facilitated diffusion

D. Osmosis

7. Absorption of vitamin A, D, E and K occurs through ______

A. Active transport

B. Simple diffusion

C. Facilitated diffusion

D. Osmosis

8. What are represented by P, Q and R?

P

Q R

P Q R

A Oxygen Potassium ion Glucose

B Potassium ion Oxygen Glucose

D Glucose Potassium ion Oxygen ion

C Oxygen Glucose Potassium ion

9. Which of the following is a difference between facilitated diffusion and active transport?

Facilitated diffusion Active transport

A Active process Passive process

C Do not require transport protein

Require transport protein

D Move against concentration gradient

Move down concentration gradient

B Do not need energy Need ATP energy

10. Which of the following statements is TRUE about active transport?

I. Requires a carrier proteinII. Movement of substances down the

concentration gradientIII. Requires expenditure of energy,usually

from ATPIV. The process is inhibited by respiratory

poison

A. II and III

B. I, II and IV

C. I, II and IV

D. I, II, III and IV

conclusion

Osmosis Facilitated diffusion

Simple diffusion

Passive transport Active transport

Movement of Substances across the Plasma Membrane

Is determined by Is based on Occurs according to Is based on

Two different method of transport

Concentration gradient of the solution

Size on polarity of the molecules

Semi-permeability of plasma membrane

Is divided

Glucose, amino acid, chloride ion

Fatty acid, glycerol

Water molecule