Enzymes Flashcards
What are enzymes responsible for?
The assembly and disassembly of macromolecules and the processing of their intermediates
What is a polymer and give biological examples
A polymer is a long molecule consisting of many similar building blocks = Carbohydrates, proteins, and nucleic acids are polymers
What are monomers?
The repeating units that serve as building blocks
What are enzymes?
Enzymes are specialized macromolecules that speed up chemical reactions such as those that make or break down polymers
What is a dehydration reaction?
A dehydration reaction occurs when two monomers bond together through the loss of a water molecule (forms a longer polymer)
What is a hydrolysis reaction?
Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction, involves the breaking of a bond
Naming a biological polymer and give the components, examples and their functions
Nucleotide (monomer of a poly nucleotide)
Sugar, Phosphate Group and Nitrogenous Base
Examples : DNA - sugar = deoxyribose, nitrogenous base = C, G, A, T and double stranded
and RNA - sugar = ribose, nitrogenous base = C, G, A, U, single stranded
Functions :
DNA - Stores hereditary information
RNA - various functions in gene expression, including carrying instructions from DNA to ribosomes
How do macromolecules vary?
Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species
Naming a biological polymer and give the components, examples and their functions
Monosaccharide monomer
Examples : Monosaccharides, Disaccharides, Polysaccharides
Functions : Fuel, Carbon sources that can be converted to other molecules or combined into polymers
Strengthens plant cell walls, Stores glucose for energy, strengthens exoskeletons and fungal cell walls
Naming a biological polymer and give the components, examples and their functions
Amino acid monomer
Examples : Enzymes, Defensive proteins, storage proteins, hormones
Functions : Catalyse chemical reactions, Protect against diseases, Store amino acids, Function in cell movement
What properties of a molecule are key to its function?
A molecule’s size and shape are key to its function, it determines how biological molecules recognize and respond to one another with specificity.
Example : Enzymes
One nerve cell in the brain signals another by releasing molecules of a specific shape to go find matching receptor molecules on the surface of the receiving cell. The signal molecules pass across a tiny gap (otherwise known as the synapse) between the two nerve cells and attach to the receptors by forming weak bonds which then stimulate the receiving cell. This process is very much like the way a key fits into a lock, where the matching puzzle-piece shapes help in the forming of weak bonds.
Opiates, such as morphine, and naturally produced endorphins have similar effects because their shapes are similar and they bind the same receptors in the brain
How is a molecules shape determined?
A molecule’s shape is determined by the positions of its atoms’ orbitals
What are the 6 different classes of enzymes?
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases (‘‘synthases’’)
- Isomerases
- Ligases (‘‘synthetases’’
What are oxidoreductases?
An oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor.
Where is oxidoreductase found in the body?
Oxidoreductase enzymes play an important role in both aerobic and anaerobic metabolism. They can be found in glycolysis, TCA cycle, oxidative phosphorylation, and in amino acid metabolism
What are transferases?
An enxyme which transfers specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor)
Give an example of transferases in the body?
Some transferases also transfer phosphate groups between ATP and other compounds, sugar residues to form disaccharides such as hexokinase in glycolysis.
What are hydrolases?
A biochemical catalysts that utilize water to break a chemical bond. This results in a division of a larger molecule to smaller molecules.
Give an example of hydrolases in the body?
Some hydrolases function as digestive enzymes because they break the peptide bonds in proteins.
What are Lyases?
They catalyze the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure) and does not require any energy
Give an example of lyases in the body?
Pyruvate decarboxylase is a lyase that removes CO2 from pyruvate
What are Isomerases?
an enzyme which catalyses the conversion of a specified compound to an isomer (where a functional group is moved to another position within the same molecule)
Give an example of isomerases in the body?
triosephosphate isomerase and phosphoglucose isomerase for converting glucose 6-phosphate to fructose 6-phosphate.
What are ligases?
can catalyze the joining of two large molecules by forming a new chemical bond by removal of the water component
Give an example of ligases in the body?
DNA ligase - that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond.
What are chemical reactions?
Chemical reactions are the making and breaking of chemical bonds
What is metabolism?
Sum of all the chemical reactions in the body - An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics
What is energy?
Energy is the capacity to cause change and exists in various forms, some of which can perform work
Energy can be converted from one form to another
What is kinetic energy?
Kinetic energy is energy associated with motion
What is thermal energy?
Thermal energy is the kinetic energy associated with random movement of atoms or molecules. Heat is thermal energy in transfer between objects
What is potential energy?
Potential energy is energy that matter possesses because of its location or structure
What is chemical energy?
Chemical energy is potential energy available for release in a chemical reaction
Are organisms a closed, open or isolated system?
Organisms are open systems
What is free energy?
Free energy is a measure of a system’s instability, its tendency to change to a more stable state (energy in a system that is free to do work)
During a spontaneous change, what happens to free energy?
During a spontaneous change, free energy decreases and the stability of a system increases
When a process is spontaneous, when can it perform work?
A process is spontaneous and can perform work only when it is moving toward equilibrium
The higher the free energy (G), what is the stability and work capacity?
Less stable, greater work capacity
The lower the free energy (G), what is the stability and work capacity?
More stable, less work capacity
Are cells in equilibrium?
Cells are not in equilibrium; they are open systems experiencing a constant flow of materials, if it were they would die. A defining feature of life is that metabolism is never at equilibrium
What are catabolic pathways and give an example
Catabolic pathways release energy by breaking down complex molecules into simpler compounds. Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism
What are anabolic pathways and give an example
Anabolic pathways consume energy to build complex molecules from simpler ones. For example, the synthesis of protein from amino acids is an anabolic pathway
Reactions in a closed system - reaching equilibrium?
Reactions in a closed system eventually reach equilibrium and can then do no work
What is a living systems free energy?
Energy that can do work when temperature and pressure are uniform, as in a living cell
Biologists want to know which reactions occur spontaneously and which require input of energy, how do they do so?
They need to determine the energy and entropy changes that occur in chemical reactions
What does the free-energy change tell us about a reaction?
The free-energy change of a reaction tells us whether or not the reaction occurs spontaneously, generates energy (exergonic) or is not spontaneous requires energy (endergonic)
What is an exergonic reaction?
reaction occurs spontaneously, generates energy (releases)
What is an endergonic reaction?
not spontaneous requires energy (absorbs free energy)
When is a reaction exergonic?
G < 0 , gibbs energy of reactants is higher than products
When is a reaction endergonic?
G > 0 gibbs energy of products is higher than reactants
How is the change in free energy (ΔG) during a process is related to the change in enthalpy—change in total energy (ΔH)—change in entropy (ΔS), and temperature in Kelvin units (T)?
ΔG = ΔH − TΔS
ΔG is negative for all spontaneous processes. Spontaneous processes can be harnessed to perform work
Processes with zero or positive ΔG are never spontaneous