Sylvia S Mader Immagini e concetti della biologia
Sylvia S. Mader Immagini e concetti della biologia 2 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
A 5 - Cellular Activity 3 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Energy has different forms Energy is the ability to do work • Radiant energy • Chemical energy • Mechanical energy 4 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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. 5 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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. 6 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Potential energy or kinetic energy? Potential 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. 7 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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”. 8 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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 9 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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”. HEAT Solar energy Chemical energy 10 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
The two laws of thermodynamics Many important biological reactions involve a loss of energy as heat. 11 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Energy flow and transformations 12 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Cellular work is powered by 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 Ribos e Phosphate groups 13 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Cellular work is powered by ATP The breaking reaction products (ADP + P) are more stable than the molecule of ATP Adenosine Triphosphate ADP + P Adenosine Diphosphate Hence, when ATP breaks down to ADP + P, energy is released. 14 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
ATP cycle ATP ➞ ADP + P exergonic reaction (releases energy) ADP + P ➞ ATP endergonic reaction (requires energy to occur) 15 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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 16 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Enzymes are catalysts Enzymes speed up the reaction by decreasing the energy of activation (Ea) of a given reaction. 17 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Factors affecting enzymes activity • Substrate concentration • Temperature • p. H • Cofactors as vitamins and coenzymes 18 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Plasma Membrane is dynamic Proteins are embedded in a phospholipid bi-bilayer in a “fluid mosaic membrane”. 19 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Membrane Proteins have various functions Channel and carrier proteins respectively allow and assist the passage of molecules through the membrane. 20 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Membrane Proteins have various functions Cell recognition proteins help the cell recognize foreign invaders. Receptor proteins bind specific molecules. 21 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Membrane Proteins have various functions Enzymatic proteins carry out metabolic reactions while junction proteins assist cell-to-cell communications. 22 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Diffusion Some small molecules or ions such as CO 2, C 6 H 12 O 6 and H 2 O, move across the plasma membrane by diffusion, a passive transport process. There are two types of diffusion: Simple diffusion Facilitated diffusion 23 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Simple diffusion Molecules in solution move down a concentration gradient until they equally distribute. 24 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Facilitate diffusion Carrier proteins facilitate diffusion of nonlipid-soluble substances across the membrane. Facilitate diffusion does not require energy. 25 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
Osmosis Water moves into a region of higher solute concentration, in order to equalize the solute concentrations on the two sides of the membrane. 26 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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 27 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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. 28 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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. 29 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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. 30 Sylvia S. Mader, Concepts of Biology © Zanichelli editore, 2018
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