MVU1 CELL CHEMISTRY AND BIOENERGETICS Flashcards
what is the bond strength?
amount of energy needed to break it
in what environment do most reactions in the body take place?
in an aqueous solution
how much stronger are covalent bonds compared to non covalent?
100x times stronger
what do covalent bonds resist?
they resist being pulled apart by thermal motions
what is the only way to break covalent bonds?
only be broken by biologically catalysed chemical reactions
how are covalent and non covalent bonds differentiated?
by bond strength
what elements make up 99% of the total atoms of the cell?
C, H, N, O
what elements make up 0.9% of the total number of atoms in the cell?
P, S, Cl, Na, Mg, K, Ca
what are the most common chemical groups in cells?
methyl (CH3)
Hydroxyl (OH)
Carboxyl (COOH)
Carbonyl (C=O)
Phosphate (PO3^-2)
Sulfhydryl (SH)
Amino (NH2)
what sorts of molecules can carbon make?
chains and rings, making many combinations
how many carbons do organic compounds usually contain?
30 carbons
where are organic compounds found?
in free solution = the aqueous solution of the cell
what are the 4 major families of organic compounds? and the groups that distinguish them
sugars (hydroxyl)
amino acid (methyl)
fatty acid (carbonyl)
nucleotide (phosphate and amino)
what are the two uses of organic compounds?
monomer subunits to construct polymeric macromolecules
energy sources –> broken down and transformed into other small molecules used in metabolic pathways
what do the building blocks give?
sugars give polysaccharides, glycogen and starch in plants
fatty acids give fats and membrane lipids (external membrane but also for intracellular organelles)
amino acids give proteins
nucleotides give nucleic acids
what are the most abundant carbon containing molecules and what are they?
proteins, the principal building and functional blocks of cells
versatile and perform thousands of functions
what is a characteristics of the assembly of macromolecules?
not random but in a sequence, subunits are added in a precise order
what do covalent bonds allow for?
allow for rotation
give flexibility which creates different conformations
what do non covalent bond do?
stabilise the different conformation, constraint the shape to one conformation
what do living cells strive for?
strive to create and maintain order
what are the two types of reactions?
anabolic and catabolic
what is the anabolic pathway?
creates bonds, we need to provide energy
condensation
energetically unfavorable
what is the catabolic pathway?
bonds are broken
energy is released
hydrolysis
energetically favorable
what is the second law of thermodynamics? and what does it mean
in any isolated system the degree of disorder always increases
order requires energy, disorder is more likely
what is entropy
the amount of disorder in a system
the greater the disorder the greater the entropy
what will systems spontaneously arrange towards?
will spontaneously rearrange towards higher S
what happens to the environment when you create more order in the cell?
the environment becomes more disordered
what is the first law of thermodynamics?
the energy can be converted from one form to the other but cannot be created/destroyed
what is released in a catabolic pathway?
heat
where is energy stored in biological systems?
in the bonds
what is enthalpy and what sort of enthalpy change is more favorable?
energy that can be released from chemical bonds
negative delta H is more favorable
what does Gibbs free energy need to be for the reaction to be favorable? and what does that mean in terms of the equation?
delta G has to be negative, therefore entropy has to be greater than the change in enthalpy
what is the gibbs free energy equation
delta G= delta H-T(delta S)
how can energetically unfavorable reactions happen?
has to be coupled to a second energy favorable reaction
what do enzymes do?
lower the activation energy
what needs to happen for the system to have a net negative gibbs free energy value?
the energy released by the energetically favorable reaction has to be greater than the energy used for the energetically unfavorable reaction
in which bond is the energy stored in ATP?
phosphoanhydride bond
what are the two steps of an ATP driven reaction?
step 1: activation
ATP transfers a phosphate to the OH group of one reactant to produce a high energy intermediate
step 2: condensation
the activated intermediate reacts with the hydrogen on the other reactant to form the product A-B accompanied with released of inorganic phosphate
what does Acetyl CoA give to the molecule?
gives the acetyl group
what does the cell need to be in?
equilibrium
what is oxidation?
removal of electrons from an atom, creation of a partial positive charge
what is reduction? and what happens with it?
addition of electrons to an atom, creation of a partial negative charge
if a molecule picks up an electron it picks up a hydrogen -> hydrogenation
