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ArianaMejiaCh8-9 Metabolism and Cell Respiration (Metabolisim (Reactions…
ArianaMejiaCh8-9 Metabolism and Cell Respiration
Forms of Energy
Energy- is the capacity to cause change
Kinetic energy
is energy associated with motion
Thermal energy
is the kinetic energy associated with random movement of atoms or molecules
Heat
thermal energy in transfer between objects
Potential energy
energy that matter possesses because of its location or structure
Chemical energy
potential energy available for release in a chemical reaction
Thermodynamics is the study of energy transformations
First law of thermodynamics
the energy of the universe is constant
The first law is also called the principle of conservation of energy
Energy can be transferred and transformed, but it cannot be created or destroyed
Second law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe
Entropy is a measure of molecular disorder, or randomness
Entropy (disorder) may decrease in a particular system, such as an organism, as long as the total entropy of the system and surroundings increases
Spontaneous processes
occur without energy input; they can happen quickly or slowly
Nonspontaneous processes
Processes that decrease entropy
occur only if energy is provided
Steps in Cellular Respiration
Glycolysis
Occurs in cytoplasm of cell near
mitochondria
breakdown of glucose by enzymes, releasing energy and pyruvic acid.
Transition Reaction
cytoplasm-mitochondria
process called oxidative decarboxylation
converts the two molecules of the 3-carbon pyruvate from glycolysis into two molecules of the 2 carbon molecule acetyl coenzyme A and 2 molecules of carbon dioxide
Krebs Cycle
mitochondrial matrix
sequence of reactions by which most living cells generate energy during the process of aerobic respiration.
consumes oxygen, producing carbon dioxide and water as waste products, and converting ADP to energy-rich ATP.
Electron Transport System
inner mitochondrial membrane
Oxygen requirement-aerobic
is a series of complexes that transfer electrons from electron donors to electron acceptors via redox reactions, and couples the electron transfer with transfer of protons across the membrane
Cellular Respiration
Aerobic
with oxygen
C6H12O6 + 6O2-----6CO2 + 6H2O + energy
One glucose molecule--------------36 or 38 ATP Glucose completely broken down
occurs in mitochondria
Produces carbon dioxide, water and energy
Anaerobic
without oxygen
Produces lactic acid and energy (muscle cells) or ethanol, carbon dioxide and energy.
Release less energy
Glucose NOT completely broken down
occurs in cytoplasm
Metabolisim
is an emergent property of life that arises from orderly interactions between molecules
Metabolic Pathway
begins with a specific molecule and ends with a product
Each step is catalyzed by a specific enzyme
Catabolic pathways
release energy by breaking down complex molecules into simpler compounds
Example is Cellular respiration, the breakdown of glucose
in the presence of oxygen
Anabolic pathways
consume energy to build complex molecules from simpler ones
Example, the synthesis of protein from amino acids is an anabolic pathway
Bioenergetics
is the study of how energy flows through living organisms
Reactions
Endergonic
absorbs free energy from its surroundings and is nonspontaneous
Exergonic
proceeds with a net release of free energy and is spontaneous
cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one
Most energy coupling in cells is mediated by ATP
ATP(adenosine triphosphate)
ATP is composed of ribose (a sugar), adenine
(a nitrogenous base), and three phosphate groups
is the cell’s energy shuttle
high energy because of the 2 covalent bonds linking the 3 phosphate groups that store a significant amount of energy
Hydrolysis of ATP
The three types of cellular work (mechanical, transport, and chemical) are powered by the hydrolysis of ATP
the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction
The recipient molecule is now called a phosphorylated intermediate
Enzymes
catalyst
is a chemical agent that speeds up a reaction without being consumed by the reaction
is a catalytic protein
example, sucrase is an enzyme that catalyzes the hydrolysis of sucrose
catalysis
enzymes or other catalysts speed up specific reactions by lowering the EA barrier
Substrate Specificity of Enzymes
The reactant that an enzyme acts on is called the enzyme’s substrate
The enzyme binds to its substrate, forming an enzyme-substrate complex
Bounding, the activity of the enzyme converts substrate to product
