BIO1011 Chapter Notes - Chapter 2.4; 8.1-8.5; 9.1-9.6: Citric Acid Cycle, Acetyl-Coa, Exergonic Reaction
14 Jun 2018
School
Department
Course
Professor
References:
Concepts: 2.4; 8.1-8.5; 9.1-9.6 from Campbell Biology
Objectives:
● Exergonic and endergonic chemical reactions
● Why organisms use enzymes to catalyse chemical reactions
● Enzymes as a specialised group of proteins and how they speed up chemical
reactions
● Effects of substrate concentrations, temps. And pH on enzyme activity
● Define oxidation and reduction
● Explain how REDOX reactions are involved in energy exchanges
● Describe the role of ATP in coupled reactions
● Explain how energy flows through the biosphere
● Explain why ATP is required for the preparatory steps of glycolysis
● Write a summary equation for glycolysis and describe where it occurs in the
cell
● Describe where pyruvic acid is oxidised to acetyl CoA, and how it links
glycolysis to the Krebs cycle
● Describe the location, molecules in and molecules out for the Krebs cycle
● Explain at what points during cellular respiration glucose is completely
oxidised
● Summarise the net ATP yield from the oxidation of a glucose molecule
Chemical Reactions
Chemical reactions is the making and breaking of chemical bonds leading to
changes in the composition of matter
Reactants are the starting materials in a reaction and the resulting materials are
called the products
All chemical reactions are theoretically reversible
A chemical equilibrium is the point at which the reactions offset one another
exactly
Catabolic and anabolic pathways
Metabolism refers to the totality of an organism’s chemical reactions
It is an emergent property of life
A metabolic pathway is a functional cluster of metabolic reactions
Catabolic pathways are pathways that comprise of degradative processes that
release energy by breaking down complex molecules into simpler compounds
Anabolic pathways consume energy to build complicated molecules from simpler
ones - sometimes called biosynthetic pathways
Forms of Energy
● Energy is the capacity to cause change
● Kinetic Energy is related to the motion of an object
find more resources at oneclass.com
find more resources at oneclass.com
● Thermal Energy is kinetic energy associated with the random movement of
atoms or molecules
○ Thermal energy transfer from one object to another is called heat
● Potential Energy is energy that is not kinetic but energy that an object
possesses because of its location or structure
● Chemical Energy is the potential energy available for release in a chemical
reaction
Laws of Energy Transformation (Thermodynamics)
● Thermodynamics is the study of energy transformations that occur in a
collection of matter
○ First law of thermodynamics (the principle of conservation of
energy)
■ The energy of the universe is constant: energy can be
transferred or transformed but it can not be created or destroyed
○ Second law of thermodynamics
■ Every energy transfer or transformation increases the entropy
(molecular disorder/randomness) of the universe
Free-energy change, �G
● Gibbs’ free energy
○ Free energy is the portion of a system’s energy that can perform work
when temp. And pressure are uniform throughout the system (as in a
living cell)
○ Enthalpy is equivalent to the total energy (in biological systems)
○ Entropy is the measure of molecular disorder or randomness
○ The change in free energy �G can be calculated for chemical reactions
by applying this equation:
■ �G = �H - T�A where �H is the change in the system’s
enthalpy, �S is the change in the system’s entropy and T is the
absolute temperature in Kelvin units (K = ℃ + 273)
○ It can also be calculated by the difference between the free energy in
its final vs. initial state:
■ �G = G(final state) - G(initial state)
■ �G can then only be -ve when the process involves a loss of
free energy
Exergonic and endergonic reactions in metabolism
● Exergonic reactions proceed with a net release of free energy (�G will be
negative in this reaction because the energy is being removed from the
substance)
● Endergonic reactions absorb free energy from its surroundings (�G will be
positive in this reaction because energy is stored into the substance)
Equilibrium and Metabolism
● Reactions in isolated systems eventually reach equilibrium and can no longer
do work
● The chemical reactions of metabolism are reversible, too
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Why organisms use enzymes to catalyse chemical reactions. Enzymes as a specialised group of proteins and how they speed up chemical. Explain how redox reactions are involved in energy exchanges. Describe the role of atp in coupled reactions. Explain how energy flows through the biosphere. Explain why atp is required for the preparatory steps of glycolysis. Write a summary equation for glycolysis and describe where it occurs in the. Describe where pyruvic acid is oxidised to acetyl coa, and how it links. Describe the location, molecules in and molecules out for the krebs cycle. Explain at what points during cellular respiration glucose is completely. Summarise the net atp yield from the oxidation of a glucose molecule glycolysis to the krebs cycle cell oxidised. Chemical reactions is the making and breaking of chemical bonds leading to changes in the composition of matter. Reactants are the starting materials in a reaction and the resulting materials are called the products.
