2. Immagini e concetti della biologia Sylvia S. Mader
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

3. A5 - Cellular Activity
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

4. Energy has different forms
Energy is the ability to do work
Radiant energy
Chemical energy
Mechanical energy
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

5. Energy has different forms
Radiant Energy (or solar energy) is the energy coming from the sun and is associated to electromagnetic waves.
Chemical Energy is the energy contained into organic molecules in the form of specific chemical bonds.
Mechanical Energy is the energy associated with any type of motion.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

6. Energy has different forms
Heat is the energy related to the motion of microscopic systems such as atoms, ions and molecules.
Calorie = the amount of energy needed to increase the temperature of 1 g of water by 1 °C.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

7. Potential energy or kinetic energy?
The energy of a body due to the position. Is a stored energy.
Kinetic energy
The energy of a body due to its motion. Is the energy in action.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

8. The two laws of thermodynamics
Thermodynamics is a branch of sciences concerned with heat flows and its relations to energy and work.
Principles applied to transformation of energy are know as “Laws of thermodynamics”.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

9. The two laws of thermodynamics
I law of Thermodynamics
(or law of conservation of energy)
“Energy can change form within the systems (solar energy can become chemical energy), but it can be neither created nor destroyed”.
Solar energy
Chemical energy
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

10. The two laws of thermodynamics
II law of Thermodynamics
“Energy cannot change from one form to another without a loss of energy in the form of heat. This heat increases the entropy (disorder) of the system”.
Solar energy
Chemical energy
HEAT
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

11. The two laws of thermodynamics
Many important biological reactions involve a loss of energy as heat.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

12. Energy flow and transformations
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

13. Cellular work is powered by ATP
ATP (Adenosine Triphosphate) is a nucleotide that consists of:
A double ring of carbon and nitrogen atoms called adenine;
A small five-carbon carbohydrate called ribose;
Three phosphate units linked together by covalent bonds.
Adenine
Ribose
Phosphate groups
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

14. Cellular work is powered by ATP
The breaking reaction products (ADP + P) are more stable than the molecule of ATP.
ATP +
ADP P
Adenosine
Triphosphate
Diphosphate
Hence, when ATP breaks down to ADP + P, energy is released.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

15. ATP cycle ATP ➞ ADP + P exergonic reaction (releases energy)
ADP + P ➞ ATP
endergonic reaction
(requires energy to occur)
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

16. ATP hydrolysis is always associated with endergonic reactions.
Coupled reactions
Reactions are coupled when the energy required for a reaction (endergonic) is provided by an exergonic reaction.
ATP hydrolysis is always associated with endergonic reactions.
Muscular contraction occurs if associated with ATP hydrolysis
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

17. Enzymes are catalysts
Enzymes speed up the reaction by decreasing the energy of activation (Ea) of a given reaction.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

18. Factors affecting enzymes activity
Substrate concentration
Temperature pH
Cofactors as vitamins and coenzymes
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

19. Plasma Membrane is dynamic
Proteins are embedded in a phospholipid bi-bilayer in a “fluid mosaic membrane”.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

20. Membrane Proteins have various functions
Channel and carrier proteins respectively allow and assist the passage of molecules through the membrane.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

21. Membrane Proteins have various functions
Cell recognition proteins help the cell recognize foreign invaders. Receptor proteins bind specific molecules.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

22. Membrane Proteins have various functions
Enzymatic proteins carry out metabolic reactions while junction proteins assist cell-to-cell communications.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

23. Diffusion
Some small molecules or ions such as CO2, O2, C6H12O6 and H2O, move across the plasma membrane by diffusion, a passive transport process.
There are two types of diffusion:
Simple diffusion
Facilitated diffusion
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

24. Simple diffusion
Molecules in solution move down a concentration gradient until they equally distribute.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

25. Facilitate diffusion
Carrier proteins facilitate diffusion of nonlipid-soluble substances across the membrane.
Facilitate diffusion does not require energy.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

26. Osmosis
Water moves into a region of higher solute concentration, in order to equalize the solute concentrations on the two sides of the membrane.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

27. Osmosis Cells placed in an isotonic solution
(iso = same) neither gain nor lose water.
Cells place in a hypotonic solution
(ipo = less) gain water.
Cells placed in a hypertonic solution
(iper = more) lose water.
Osmosis effects on animal and plant cells
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

28. Active transport
In order to move a substance against its concentration gradient the consumption of energy (ATP) is required.
Carrier proteins involved in active transport are called pumps.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

29. Endocytosis
Endocytosis is the process by which cells absorb big particles by engulfing them.
Most biologically important substances are large molecules that cannot pass through the plasma membrane.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018

30. Exocytosis
Exocytosis is the process by which vesicles transport substances as digestive enzymes and hormones out of the cell.
Transport of massive particles (macromolecules) in and out the cell membrane requires the use of vesicles.
Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018