Essay About Biological Reactions And Condensation Reactions

Yeast Experiment
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kdjsodjsdnkkkkndYeast Experiment
Yeast is a single celled fungus (commonly used to ferment alcohol).
Yeast is a facultative anaerobe. This means that it can release
energy from food through anaerobic or aerobic respiration.
Yeast will respire aerobically if oxygen is present use oxygen if it
is present, If it does so; it will break down its respiratory
substrate to release energy for the formation of ATP. The products
of this process are carbon dioxide and water. The equation for aerobic
breakdown of glucose: C6H12O6 + 6O2 6 CO2 + 6 H2O + energy
Yeast will use oxygen if it is present, and break down sugars all the
way to CO2 and H2O. In the absence of oxygen, yeast will switch to an
alternative pathway that does not require oxygen this will produce
ethanol & CO2. The anaerobic pathway is shown below:
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Fermentation is the process by which sugar is converted to alcohol
using yeast, this is the anaerobic breakdown of a nutrient molecule
like glucose. This process does no release all energy in the molecule
but allows glycolysis to take place; the pathway of glycolysis is
shown below:
During respiration, high energy carbon bonds are broken. Lower energy
bonds are formed and the difference is released and used to make ATP
from ADP.
Glycolysis splits glucose in to 2 molecules of 3carbon-triose
phosphate, hydrogen is then released and ATP made. From this 2
molecules of pyruvate are made and in total 4 molecules of ATP.
However the net gain of ATP is only 2 molecules as ATP is put in to
the process at the beginning to fuel it. In the absence of oxygen
glucose is broken down in to pyruvic acid but if oxygen is needed to
act as the final hydrogen acceptor to break down the sugar further.
Pyruvic acin then enters the next stages of respiration, which are:
* The Krebs cycle – whereby hydrogen id removes from the pyruvic acid
* The electron transport chain – The hydrogen is used to make ATP
The outcome of this whole process is 6ATP molecules
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Metabolism and the breakdown of substances can be measured using the
respiration quotient. The respiratory quotient (RQ) measures the ratio
of the volume of carbon dioxide (Vc) produced by an organism to the
volume of oxygen consumed (Vo). This is represented by the following
equation: Vc / Vo
Enzymes – these are a major part of respiration therefore may affect
the rate of respiration.
Enzymes speed up or catalyse biological reactions within the human
body for example hydrolysis or condensation reactions. During a
reaction the substrate will bind to the active site of an enzyme this
will only occur if it is given some extra energy referred to as
activation energy, in order to start the reaction. In order for a
reaction to take place the substrate needs to collide with the active
site, the speed at which the enzymes collide affects the rate of
reaction as more collisions means a faster reaction, this can be done
by heating. The core body temperature of humans is 37C which is
generally higher than hat of the surrounding environment this is the
temperature at which reactions take place at a sufficient rate.
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Several variables affect the rate of enzyme reaction, the table below
is based on the fact that one variable is altered at a time while the
others remain constant
Variable
Effect
Enzyme concentration
Initially, reaction rates will increase. This is because there are
more enzyme active sites available to catalyse the reaction. The rate
will slow as the substrate concentration declines. Reaction rate is
faster with higher concentrations but this slows down as the amount of
substrate starts to decline. The more enzymes the more active sites
there are for substrates to slot in to although this depends also on
there being enough substrate once this runs out the reaction will slow
Substrate concentration
Increases the rate of initial reaction but once substrate exceeds the
quantity of the active site the reaction will slow
Temperature
Reactions are slow at lower temperatures; higher temperatures speed up
the movement of the enzymes and increase the chance of collisions.
However