Unit 6
All the reactions taking place in an organism
Anabolism
Anabolic rxn
Building up large molecules
Using dehydration rxn
Catabolism
Catabolic rxn
Breaking down large molecules
Using hydraulic rxn
The first law of thermodynamics:
Energy is neither created nor destroyed; instead, energy changes from one form to another
The second law of thermodynamics:
Systems are not efficient; energy is always lost to the surroundings, resulting in disorder, which is called entropy, measured in temp
Living things are constantly working against entropy by trying to maintain their homeostasis, a constant internal environment. We fight disorder and when we begin to lose, we start to age & die.
Energy is the ability to do work.
Forms of energy
Kinetic: increate in KE → inc heat
Potential: stored energy located in the bonds; stronger bonds = more energy
Heat: the amount of collisions particles form with each other & surroundings
Temperature: the average movement of particles
Different energy forms of chemicals
Ordered with high energy bonds; very reactivity
Exp: ATP dec Δs
Ordered with low energy bonds; low reactivity
Exp: glucose, glycogen, lipids dec Δs
Disordered with low energy bonds: low reactivity
Exp: ADP, CO2 Inc Δs
The most common chemical used in biology is ATP
ATP → ADP + Pi
Adenosine triphosphate → adenosine diphosphate + inorganic phosphate
Coupling reactions
When two rxn are paired together, one is exergonic, supplying energy to the second rxn, which is endorgonic, allowing it to occur.
Most common forms of cellular work
Chemical Work:
Definition: Chemical work involves the synthesis of complex molecules, the breakdown of larger molecules into simpler ones, and the conversion of one type of molecule into another.
Example: An essential example of chemical work is the synthesis of adenosine triphosphate (ATP), which serves as the primary energy currency of cells. During cellular respiration, cells break down glucose into carbon dioxide and water, releasing energy that is used to produce ATP.
Transport Work:
Definition: Transport work involves the movement of substances across cellular membranes. This can include the active transport of ions or molecules against their concentration gradient, requiring energy input.
Example: The sodium-potassium pump is a classic example of transport work. This pump actively transports sodium ions out of the cell and potassium ions into the cell against their respective concentration gradients, using energy derived from ATP hydrolysis.
Mechanical Work:
Definition: Mechanical work involves the physical movement or mechanical manipulation of cellular structures. This includes activities such as muscle contraction and the movement of cilia and flagella.
Example: Muscle cells perform mechanical work during contraction. The interaction between actin and myosin filaments, powered by ATP, leads to the shortening of muscle fibres and the generation of mechanical force.
Proteins (sometimes RNA) that lower the Ea to allow reactions to happen faster
How is the Ea lowered?
Enzyme brings reactants close to each other
Brings reactants together in the correct orientation
Places stress on bonds, allowing them to break and form more readily
Substrates (reactants) enter into the active site of the enzyme in the correct orientation
The active site is a specific region of the enzyme where the reaction takes place
receptors/transport proteins do now have an active site; they have a binding site instead. the binding site is for attachment, holding things
Each enzyme is specific to a substrate that is called the lock-and-key mechanism
Substrates are attached to the active site, and as soon as they enter it, the active site will wrap tightly around the substrates; this is called induced fit
Once substrates are in the enzyme, the enzyme-substrate complex is formed, where the substrate is held by weak intermolecular force in the active site
The enzyme lowers the Ea by placing stress on the bonds of the substrate using the weak intermolecular forces
The stress on the bonds created by the active site will allow bonds to break and new ones to form, generating products.
Products are repelled by the active site, causing them to leave the enzyme
Enzyme returns back to its original conformation, ready to receive a new substrate
Other chemicals can help enzymes function, such as…
Inorganic chemicals called cofactors
Exp: zinc, manganese, copper
Organic chemicals called coenzymes
Factors that disrupt enzyme function (all stress)
Pressure
Temperature
pH
Salt concentration
Electricity
poison/inhibitors
These change the structure of the enzyme, resulting in denaturation
In the active form (more common in bio)
Always function and must be turned off when not needed (inhibited)
Inactive form
Produced in a nonfunctioning form and must be turned on or activated
Controlling the function of active enzymes
Inhibitors are chemicals that will inactivate enzymes
Two types…
1. Competitive inhibitors
Will compete with the substrate for the active site
This can be controlled by changing the substrate concentration
More substrate, lower chance of activation
Reversible competitive inhibitor
Inhibitor temporarily attaches to the active site and can leave
Irreversible competitive inhibitor
Permanently attaches to the active site and will not leave
2. Non-competitive inhibitors
Will attach to the enzyme at another location called the allosteric site, causing the active site to change in shape so that substrates will not fit properly
Or blocks the active site so substrates can’t enter
Exists as reversible and irreversible
Feedback activation
As more products are created, this causes enzymes to work more and produce even more products
Feedback inhibition
As products increase in amount, the enzyme will be inactivated
The concentration of the product is the inhibitor
Example: threonine (amino acids) changes by a series of reactions to isoleucine, the isoleucine attaches have an allosteric site, inhibiting the cell. When isoleucine is used up, it will detach.
All the reactions taking place in an organism
Anabolism
Anabolic rxn
Building up large molecules
Using dehydration rxn
Catabolism
Catabolic rxn
Breaking down large molecules
Using hydraulic rxn
The first law of thermodynamics:
Energy is neither created nor destroyed; instead, energy changes from one form to another
The second law of thermodynamics:
Systems are not efficient; energy is always lost to the surroundings, resulting in disorder, which is called entropy, measured in temp
Living things are constantly working against entropy by trying to maintain their homeostasis, a constant internal environment. We fight disorder and when we begin to lose, we start to age & die.
Energy is the ability to do work.
Forms of energy
Kinetic: increate in KE → inc heat
Potential: stored energy located in the bonds; stronger bonds = more energy
Heat: the amount of collisions particles form with each other & surroundings
Temperature: the average movement of particles
Different energy forms of chemicals
Ordered with high energy bonds; very reactivity
Exp: ATP dec Δs
Ordered with low energy bonds; low reactivity
Exp: glucose, glycogen, lipids dec Δs
Disordered with low energy bonds: low reactivity
Exp: ADP, CO2 Inc Δs
The most common chemical used in biology is ATP
ATP → ADP + Pi
Adenosine triphosphate → adenosine diphosphate + inorganic phosphate
Coupling reactions
When two rxn are paired together, one is exergonic, supplying energy to the second rxn, which is endorgonic, allowing it to occur.
Most common forms of cellular work
Chemical Work:
Definition: Chemical work involves the synthesis of complex molecules, the breakdown of larger molecules into simpler ones, and the conversion of one type of molecule into another.
Example: An essential example of chemical work is the synthesis of adenosine triphosphate (ATP), which serves as the primary energy currency of cells. During cellular respiration, cells break down glucose into carbon dioxide and water, releasing energy that is used to produce ATP.
Transport Work:
Definition: Transport work involves the movement of substances across cellular membranes. This can include the active transport of ions or molecules against their concentration gradient, requiring energy input.
Example: The sodium-potassium pump is a classic example of transport work. This pump actively transports sodium ions out of the cell and potassium ions into the cell against their respective concentration gradients, using energy derived from ATP hydrolysis.
Mechanical Work:
Definition: Mechanical work involves the physical movement or mechanical manipulation of cellular structures. This includes activities such as muscle contraction and the movement of cilia and flagella.
Example: Muscle cells perform mechanical work during contraction. The interaction between actin and myosin filaments, powered by ATP, leads to the shortening of muscle fibres and the generation of mechanical force.
Proteins (sometimes RNA) that lower the Ea to allow reactions to happen faster
How is the Ea lowered?
Enzyme brings reactants close to each other
Brings reactants together in the correct orientation
Places stress on bonds, allowing them to break and form more readily
Substrates (reactants) enter into the active site of the enzyme in the correct orientation
The active site is a specific region of the enzyme where the reaction takes place
receptors/transport proteins do now have an active site; they have a binding site instead. the binding site is for attachment, holding things
Each enzyme is specific to a substrate that is called the lock-and-key mechanism
Substrates are attached to the active site, and as soon as they enter it, the active site will wrap tightly around the substrates; this is called induced fit
Once substrates are in the enzyme, the enzyme-substrate complex is formed, where the substrate is held by weak intermolecular force in the active site
The enzyme lowers the Ea by placing stress on the bonds of the substrate using the weak intermolecular forces
The stress on the bonds created by the active site will allow bonds to break and new ones to form, generating products.
Products are repelled by the active site, causing them to leave the enzyme
Enzyme returns back to its original conformation, ready to receive a new substrate
Other chemicals can help enzymes function, such as…
Inorganic chemicals called cofactors
Exp: zinc, manganese, copper
Organic chemicals called coenzymes
Factors that disrupt enzyme function (all stress)
Pressure
Temperature
pH
Salt concentration
Electricity
poison/inhibitors
These change the structure of the enzyme, resulting in denaturation
In the active form (more common in bio)
Always function and must be turned off when not needed (inhibited)
Inactive form
Produced in a nonfunctioning form and must be turned on or activated
Controlling the function of active enzymes
Inhibitors are chemicals that will inactivate enzymes
Two types…
1. Competitive inhibitors
Will compete with the substrate for the active site
This can be controlled by changing the substrate concentration
More substrate, lower chance of activation
Reversible competitive inhibitor
Inhibitor temporarily attaches to the active site and can leave
Irreversible competitive inhibitor
Permanently attaches to the active site and will not leave
2. Non-competitive inhibitors
Will attach to the enzyme at another location called the allosteric site, causing the active site to change in shape so that substrates will not fit properly
Or blocks the active site so substrates can’t enter
Exists as reversible and irreversible
Feedback activation
As more products are created, this causes enzymes to work more and produce even more products
Feedback inhibition
As products increase in amount, the enzyme will be inactivated
The concentration of the product is the inhibitor
Example: threonine (amino acids) changes by a series of reactions to isoleucine, the isoleucine attaches have an allosteric site, inhibiting the cell. When isoleucine is used up, it will detach.
