Chapter 6 - Energy & Life Flashcards
What is metabolism?
The whole range of biochemical processes that occur within a living organism. Metabolism consists of anabolism (the buildup of substances) and catabolism (the breakdown of substances)
What is a metabolic pathway?
A metabolic pathway is a linked series of chemical reactions occurring within a cell.
What are catabolic pathways?
Metabolic pathways that release energy by breaking down complex molecules to simpler compounds.
What are anabolic pathways?
Metabolic pathways that consume energy to build complicated molecules from simpler ones; they are some- times called biosynthetic pathways.
What is a major catabolic pathway?
Cellular respiration, in which the sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water. (Pathways can have more than one starting molecule and/or product.)
What is are 2 examples of an anabolic pathways in the human body?
The synthesis of an amino acid from simpler molecules and the synthesis of a protein from amino acids
Define energy?
The capacity to cause change
What is kinetic energy?
Energy that is associated with the relative motion of objects.
What is thermal energy?
Thermal energy is kinetic energy associated with the random movement of atoms or molecules; thermal energy in transfer from one object to another is called heat. Light is also a type of energy that can be harnessed to perform work, such as powering photosynthesis in green plants.
What is chemical energy?
Chemical energy is a term used by biologists to refer to the potential energy available for release in a chemical reaction. For example glucose in food.
True or False? Organisms are energy transformers.
True
What is thermodynamics?
The study of the energy transformations that occur in a collection of matter.
What is an isolated system?
unable to exchange either energy or matter with its surroundings outside the thermos.
What is an open system?
Energy and matter can be transferred between the system and its surroundings.
True or False? Organisms are isolated systems.
False, organisms are open systems
What is the first law of thermodynamics?
The energy of the universe is constant: Energy can be transferred and transformed, but it cannot be created or destroyed. also known as the principle of conservation of energy.
What is the Second law of thermodynamics?
Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, as a bear runs, disorder is increased around its body by the release of heat and small molecules that are the by-products of metabolism.
Why can’t organisms simply recycle their energy over and over again?
during every energy transfer or transformation, some energy becomes unavailable to do work. In most energy transformations, the more usable forms of energy are at least partly converted to thermal energy and released as heat.
What is entropy?
Entropy is a measure of uncertainty or randomness. The more randomly arranged a collection of matter is, the greater its entropy
If entropy is increased is your reaction more or less favoured?
More favoured.
What is a spontaneous process?
A process that can proceed without requiring an input of energy. Signifying that it is energetically favorable. -DELTA G
Do spontaneous reactions all occur at the same speed?
No for example an explosion is much faster than a car deteriorating over time.
What are non-spontaneous reactions?
A process that, on its own, leads to a decrease in entropy as it will happen only if energy is supplied. +DELTA G
how does the second law of thermodynamics help explain diffusion, the random thermal motion of particles, across a membrane?
The second law is the trend toward randomisation, or increasing entropy. When the concentration of a substance on both sides of a membrane are equal, the distribution is more favoured than when they are unequal.
What is the function of the Gibbs free energy of a system (without considering its surroundings)? G
The Gibbs free energy (G) of a system is a measure of the amount of usable energy (energy that can do work) in that system. The change in Gibbs free energy during a reaction provides useful information about the reaction’s energetics and spontaneity (whether it can happen without added energy)
What is free energy?
Free energy is the portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. We can think of free energy as a measure of a system’s instability- its tendency to change to a more stable state.
The change in free energy, ∆G, can be calculated for a chemical reaction by applying the following equation?
∆G = ∆H - T∆S
∆H symbolises the change in the system’s enthalpy (in biological systems, equivalent to total energy); ∆S is the change in the system’s entropy; and T is the absolute temperature in Kelvin (K) units
What can we use delta G to determine?
Whether a reaction will be spontaneous or not. processes with a negative ∆G are spontaneous.
What is the equation for delta G?
∆G = Gfinal state - Ginitial state
When a reaction goes away from equilibrium what happens to the value of the free energy?
It increases. Therefore G increases
A change from the equilibrium position will have a positive or negative G?
Positive as this is a non-spontaneous reaction and requires energy.
What are exergonic reactions?
“energy outward” An exergonic reaction proceeds with a net release of free energy. Because the chemical mixture loses free energy (G decreases), ∆G is negative for an exergonic reaction. This reaction is spontaneous
What are endergonic reactions?
“energy inward” An endergonic reaction is one that absorbs free energy from its surroundings. Because this kind of reaction essentially stores free energy in molecules (G increases), ∆G is positive. Such reactions are non-spontaneous,
True or False? The greater the decrease in free energy, the greater the amount of work that can be done.
True
If ∆G = -686 kcal/mol for respiration, which converts glucose and oxygen to carbon dioxide and water what would the reverse reaction be?
The conversion of carbon dioxide and water to glucose and oxygen must be strongly endergonic, with ∆G = +686 kcal/mol. Such a reaction would never happen by itself.
How do plants make the sugar that organisms use for energy?
Plants get the required energy—686 kcal to make a mole of glucose—from the environment by capturing light and converting its energy to chemical energy. Next, in a long series of exergonic steps, they gradually spend that chemical energy to assemble glucose molecules.
What is metabolic equilibirum?
When metabolic reactions in an isolated system eventually reach equilibrium and can then do no work
What happens when a cell reacher metabolic equilibrium?
It is dead
Is a living cell in equilibrium?
No or else it would be dead. The constant flow of materials in and out of the cell keeps the metabolic pathways from ever reaching equilibrium, and the cell continues to do work throughout its life.
Why do metabolic cells barely ever reach equilibrium?
The constant flow of materials in and out of the cell keeps the metabolic pathways from ever reaching equilibrium, and the cell continues to do work throughout its life.
Why do some of the processes in cellular respiration never reach equilibrium?
Because the product of a reaction does not accumulate but instead becomes a reactant in the next step of cellular respiration. As long as our cells have a steady supply of glucose or other fuels and oxygen and are able to expel waste products to the surroundings, their metabolic pathways never reach equilibrium and can continue to do the work of life.
Is cellular respiration endothermic or exothermic?
It is an exothermic reaction because it creates chemical energy in the form of ATP. Although there is an endothermic step in glycolysis. Glycolysis is the breakdown of glucose into 2 pyruvate molecules.
What 3 types of work do cells do?
Chemical work, transport work, and mechanical work
What is chemical work?
The pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers
What is transport work?
The pumping of substances across membranes against the direction of spontaneous movement
What is mechanical work?
Such as the beating of cilia, the contraction of muscle cells, and the movement of chromosomes during cellular reproduction
What is energy coupling?
The use of an exergonic process to drive an endergonic one. ATP is responsible for mediating most energy coupling in cells, and in most cases it acts as the immediate source of energy that powers cellular work.
What does ATP contain?
The sugar ribose with the nitrogenous base adenine and a chain of 3 phosphate groups bonded to it.
True or False? ATP is one of the nucleoside triphosphate’s used to make RNA.
True!
How are the bonds between the phosphate groups of ATP broken and what is the result of this?
Hydrolysis, the addition of a water molecule results in a molecule of the inorganic phosphate leaving the ATP resulting in ADP. This reaction is exergonic as it released 7.3 cal of energy per mole of ATP hydrolized.
What is the reaction for the production of ADP?
ATP + H2O > ADP + P (Inorganic phosphate group)
What are the phosphate bonds of ATP sometimes referred to and why?
High-Energy phosphate bonds because their hydrolysis releases energy but this is misleading because these bonds of ATP are not usually that strong. Rather it is ATP and H2O (reactants) that are high-energy relative to the products, ADP & P (Inorganic phosphate group) .
