section 5 Flashcards
metabolism
all the life-sustaining reactions going on in an organism
anabolic reactions
simple to complex reactions. Biosynthetic. energy input required for this
how much energy is there for products compared to reactants in anabolic/ biosynthetic reactions
products have more energy than reactants in anabolic reactions
catabolic reactions
breakdown reactions. complex to simple. energy is released
what is an example of a catabolic reaction
hydrolytic reactions: breakdown of polymers into monomers
energy
the capacity to do work or cause change. rearranges collection of matter
heat energy
thermal energy released or transferred from one object to another
chemical energy
the potential energy stored in the chemical bonds of molecules (ATP)
radiant energy
light energy
nuclear energy
energy in atoms
The first law of thermodynamics
energy can be transferred and transformed but cannot be destroyed or created. living organisms are energy transformers but not energy creators
the second law of thermodynamics
energy transfers or transformations increase the entropy of the universe. in reactions in the body order will be increased locally but will be decreased in the universe
entropy
disorder
what happens to a small amount of heat during transfers and transformations
in every energy conversion, some energy becomes unusable and is no longer available to do works it is lost in form of heat and small molecules which dissipate
is a process that leads to increased entropy favourable or not favourable
it is favourable. proceeds without the input of energy. breakdown of things. they are spontaneous
Gibbs free energy
the energy available to do work
why is some energy unusable in molecules?
because there is an entropy requirement
exergonic
reactions, where the molecules produced, have less energy than the free energy in the reactants
what is an ERG
10 joules
are exergonic reactions spontaneous or not and are the produces less stable or more stable
they are spontaneous and catabolic. the products are more stable
the trend of G and the ability to do work
the less G is, the more stable the system is and the higher capacity to do work
what is the structure of ATP
ribose sugar
adenine
chain of three phosphate groups (triphosphate)
what is ATP broken down into during hydrolysis reactions?
ADP and inorganic phosphate
is the breakdown of ATP and H2O exergonic?
yessir
how do we deal with the loss of energy in the breakdown of ATP
the catabolic reaction is coupled with an anabolic reaction. the released energy of the catabolic reactions is captured by anabolic reactions.
what are the three types of work that need energy input from the hydrolysis of ATP?`
- chemical work
- transport work
- mechanical work
what is the delta G for ATP hydrolysis?`
-30.5kj/mol
how can we do anabolic reactions and still follow the rules of thermodynamics?
by coupling anabolic reactions (building complex materials) with catabolic reactions (the breakdown of things)
why don’t spontaneous reactions happen spontaneously in biological systems?
because chemical reactions involve the breaking of bonds and forming bonds. changing molecules involves contorting molecules into unstable formations so the bonds can be broken and configured into something new. This means that we need an initial input of energy to get bonds into this unstable form. This is the activation energy
what is used for activation energy in non-biological systems and why is it inappropriate to use in biological systems
heat. it is inappropriate because
1. it’s indiscriminate: does not only affect the part you’re working on. it affects everything
2. damaging: organisms function within a preferred range of temp. higher temps denature proteins, destroy membranes, and the organism dies
what enzyme is not a protein
riboenzymes
does enzyme shape change after it catalyzes a reaction?
no, enzymes speed up a reaction without being changed or used up by the reaction
how do enzymes work in reactions?
enzymes work to lower the activation energy barrier. this happens at the active site. reactants fit into the active site to form an enzyme-substrate complex and the enzyme closes upon the substrate.
- they line up reactants in the way that reactions are facilitated
- pull and contort substrates into their transition to destabilize them
- active site provides microenvironment good for reaction (pH etc)
- enzymes briefly covalently bond with parts of the reactants
active site
a location on the enzyme that is a perfect structural fit for the reactant
relation of AE and bond strength
activation energy is proportional to the difficulty in breaking bonds. stressing the bonds makes them easier to break and lowers the activation energy which is what enzymes do
what is the rate of reaction a function of
the concentration of substrates and the number of enzymes. adding substrates increases reaction rate until a certain point when you will have to add more enzymes
when is an enzyme denatured
when it has moved too far away from its optimal conditions.
enzyme optimal conditions
the specific range of conditions when an enzyme is in its most active 3D configuration (pH, temp presence/ absence of cofactors)
what is the ph that most enzymes work in
6-8
the pH of pepsin- stomach
2
the pH of trypsin- small intestine
8
what are the two cofactors?
- inorganic cofactors (metal ions such as zinc)
2. organic coenzymes
where are inorganic cofactors found on enzymes
might be permanently bound or reversibly bound along with the substrate
what are coenzymes
vitamins
enzyme inhibitors
molecules that prevent enzymes from working properly
- competitive inhibitors
- non-competitive inhibitors
competitive inhibitors
bind reversibly onto the active site and can be dealt with by increasing the concentration of substrate so it can compete more effectively for the active site
non-competitive inhibitors
bind somewhere other than the active site and distort the 3D shape of the enzyme, therefore, rendering the active site less effective or non-functional. maybe reversible. can be useful such as in the case of negative feedback
example of non-competitive inhibitors
negative feedback things.
irreversible inhibition
this is the case for poisons and toxins
how can irreversible enzyme inhibitors work to our benefit
antibiotics alter or block active sites on the enzymes of bacteria. e.g. penicillin inhibit enzymes involved in bacterial cell wall production
what are nerve agents and give an example
sarin gas: binds to R group on amino acid sarine (on active site of acetylcholinesterase) this leads to your nerves continuously firing and leads to loss of muscle control, paralysis, respiratory failure and death
what is the principle process of regeneration
cellular respiration
what are the three ways to regenerate ATP
- cellular respiraton
- anerobic respiration
- fermentation
where do electrons go in redox reactions?
to the more electronegative atom
what does the relocation of electrons do?
releases energy
what are chemicals that get electrons called
oxidizing agents
what are chemicals that give electrons called
reducing agents
how much potential energy do electrons that are with less electronegative chemicals have
they have more potential energy since energy is required to be inputted to pull electrons away from strongly electronegative atoms
is energy inputted or released when electrons go from less to more electronegative chemicals
the potential energy is released in a stepwise fashion by a series of controlled redox reactions with a bit of energy released at each step to work
what does it mean to be an excellent source of hilltop molecules?
organic molecules that have an abundance of hydrogen are called hilltop molecules
what are the three stages of cellular respiration?
- glycolysis
- oxidation of pyruvate followed by the citric acid cycle (Kreb’s cycle)
- oxidative phosphorylation electron transport and chemiosmosis
the 2nd and 3rd parts take place in the mitochondria and the first part is in the cytosol
where does glycolysis take place?
in the cytosol
what are the reactants in glycolysis?
2NAD+ and 2ATP and glucose
what are the products of glycolysis?
2ATP, 2NADH and 2Pyruvate and hydrogen ions
what is substrate-level phosphorylation?
a process whereby a phosphate group is transferred to ADP from another molecule by an enzyme. a substrate carrying the phosphate group goes into an enzyme with an ADP molecule and the produce is ATP. 4 ATP are produced but two are used so the net gain is 2.
where does the citric acid take place?
in the mitochondrion matrix
