Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 8: An introduction to Metabolism (Concept 8.1 (Metabolism: The…
Chapter 8:
An introduction to Metabolism
The energy of life
Sugars can be converted to Amino Acids that are linked together into proteins when needed
In multicellular organisms, many cells export chemical products that are used in other parts of the organisms
Cellular respiration: the process in which extracts the energy stored in sugars and other fuels
Bioluminescent
Bioluminescence and other metabolic activities carried out by a cell are precisely coordinated and controlled
concept 8.3
ATP powers cellular work by coupling exergonic reactions and endergonic reactions
Cell 3 main works
Chemical work
transport work
mechanical work
Energy coupling:
the use of exergonic process to drive an endergonic one
ATP is responsible for mediating most energy coupling in cells
Concept 8.1
AN organism's metabolism transforms matter and energy, subject to the the laws of thermodynamics
Metabolism: The totality of an organism's chemical reaction
the emergent property of life that arises from orderly interactions between molecules
manages the material and energy resources of the cell
Catabolic pathways:
pathways that release energy by breaking down complex molecules to simpler compounds
Major pathway is CELLULAR RESPIRATION
Metabolic Pathways:
begins with a specific molecule, which is then altered in a series of defined steps, resulting a certain product
Each step is catalyzed by a specific enzyme
mechanisms regulate the enzymes, thus balancing metabolic supply and demand
Anabolic pathways:
consume energy to build complicated molecules from simpler ones; they are sometimes called
biosynthetic pathways
EX: synthesis of amino acids from simpler molecules
Catabolic and anabolic are the "uphills" and "downhills" avenues of the metabolic landscape
Energy released from the "downhill" reactions of the catabolic pathways can be stored and then used to drive the "uphill" reactions of anabolic pathways
Bio Genetics:
the study of how energy flow through living organisms
Energy
: the capacity to cause change
Exists in various forms, and the work of life depends on the ability of cells to transform energy from one form to another
Kinetic energy:
the form of energy relative to the motion of objects
Thermal energy: kinetic energy associated with the random movement of atoms or molecules
Thermal energy tranfered betweeen objects is
HEAT
Potential Energy:
energy possessed due to the location or structure of the matter
Chemical energy: the potential energy available for release in a chemical reaction
During a catabolic reaction, some bonds are broken and others are formed, releasing energy and resulting in lower-energy breakdown products
Biochemical pathways, carried out in the context of cellular structures, enable cells to release chemical energy from food molecules and use the energy to power life processes
Thermodynamics:
the study of energy transformation that occur in a collection of matter
Isolated system
: unable to exchange either energy or matter with its surroundings outside the thermos
Open system
: energy and matter can be transferred between the system and surroundings
organisms are open
Two laws of thermodynamics govern energy transformations in organisms and all other collections of matter
1st law: the energy of the universe is constant (principle of conservation of energy)
2nd law: every energy transfer or transformation increases the entropy of the universe
the more usable forms of energy are at least partly converted to thermal energy and released as heat
living cells unavoidably convert other forms of energy to heat
Entropy:
the measure of molecular disorder or randomness
the more random the more entropy
The physical disintegration of a system's organized structure is a good analogy for an increase in entropy
Living systems increase the entropy of their surroundings
an organism also takes in organized forms of matter and energy from the surroundings and replaces them with less ordered forms
Spontaneous process: process can proceed without requiring an input of energy
Some may be virtually instantaneous, while others are much slower
Nonspontaneous process: process that, on its own, leads to a decrease in entropy
some energy is inevitably lost as heat, increasing, increasing entropy in the surroundings
Concept 8.2
The free energy change of a reaction tells us whether or not the reaction occurs spontaneously
Free energy: the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in living cells
when a process occurs spontaneously in a system theta G is negative
can only be negative when the process involves a loss of free energy during the change
concept 8.4
concept 8.5
regulation of enzyme activity helps to control metabolism
chemical chaos would result if all a cell's metabolic pathways were operating simultaneously
genes are switched on and off which encodes specific enzymes
Allosteric Regulation:
any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate site
enzymes constructed of from two or more subunits, each composed of a polypeptide chain in its own active site
Substrate molecule: another form of allosteric reaction
Cooperativity
: mechanism that amplifies the response of enzymes to substrates
Feedback inhibition:
a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway
prevents the cell from making more isoleucine than is necessary and thus wasting chemical resources
Phosphorylated intermediate: the recipient molecule with the phosphate group covalently bonded to it
The key to coupling energy is the formation of the phosphorylated intermediate, which is more reactive than the original molecule
Transport and mechanical work in the cell are also nearly always powered by the hydrolysis of ATP
leads to a change in a protein's shape and often its ability to bind to another molecule
An organism at work uses ATP continuously
ATP is a renewable resource that can be regenerated by the addition of phosphate to ADP
Since ATP formation from ADP is not spontaneous, free energy must be spent to make it occur
free energy comes from exergonic breakdown reactions in the cells
ATP cycle couples the cell's energy-yielding processes to the energy consuming ones
Catabolic (exergonic) pathways, especially cellular respiration provide the energy for the endergonic processes of making ATP