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FULL TEST BANK Essential Cell Biology, 4th Edition 4th Edition by Bruce Alberts (Author) Graded A+ latest update.
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Test Bank for Essential Cell Biology, 4th Edition by Bruce Alberts, 9780815345251, Covering Chapters 1-20 | Includes Rationales
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Test Bank for Essential Cell Biology, 4th Edition by Bruce Alberts, 9780815345251, Covering Chapters 1-20 | Includes Rationales
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The Effects of Oxygen of the Rate of Carbon Dioxide Production in Yeast CellsAn Introduction to Cellular Respiration
As a biological process, cellular respiration occurs inside the cells of an organism, where macromolecules such as
carbohydrates, namely glucose, are broken down and released as energy, which can then be utilized by the cells of an organism to
perform the necessary processes. Cellular respiration begins with glucose, a simple sugar, which is broken down by the various
steps of cellular respiration to yield adenosine triphosphate (ATP), which is utilized for various cellular functions. ATP is
composed of three phosphate groups, and energy is released when one of these phosphate groups is removed, this results in the
formation of adenosine diphosphate (ADP). Cellular respiration is responsible for transforming ADP back to ATP, it does so by
adding back the third phosphate group. The process of cellular respiration is one that can be broken into three primary steps,
Glycolysis, the Citric Acid Cycle (also referred to as the Krebs Cycle) and, the Electron Transport Chain (ETC).
Glycolysis - The First Stage of Cellular Respiration
During the stage of glycolysis, the cell takes in a molecule of glucose, and proceeds to break it down into two molecules
of pyruvate, which is an organic molecule which is composed of a three-carbon backbone. In order to breakdown the molecule of
glucose, the cells utilizes two molecules of ATP, however, the stage of glycolysis also produces four molecules of ATP, resulting in
the net gain of two molecules of ATP.
The Citric Acid Cycle - The Second Stage of Cellular Respiration
As the second stage of cellular respiration, the citric acid cycle take place inside of the mitochondria, often referred to as
the power house of cell, as they are responsible to transforming the pyruvate molecules into ATP, which is the usable form of
energy. The two molecules of pyruvate undergo a series of processes, resulting in the formation of two additional molecules of
ATP and carbon dioxide. Additionally whilst the two molecules of pyruvate undergo the series of biological processes, the citric
acid acid cycle take electrons from the two molecules of pyruvate, and adds them to carrier molecules, which transport the
electrons to the third stage of cellular respiration, the Electron Transport Chain. At this point in the process of cellular respiration,
the cell has produced four molecules of ATP.
The Electron Transport Chain - The Third Stage of Cellular Respiration
As the final stage of cellular respiration, the electron transport chain takes place across a membrane, in the case of
eukaryotic organisms, this happens to be across the mitochondrial membrane and in the case of prokaryotic organisms, it happens
to be across the cellular membrane. In the electron transport chain, the electron carrying molecules created in the citric acid cycle,
release their electrons into the membrane. As the removed electrons travel across the membrane, they release some of their energy
to transport proteins, which are also located inside the membranes. The energy released by the electrons is responsible for
powering the transport proteins, which allows them to pump hydrogen ions to the opposite side of the membrane. The electrons
are then passed along to several transport proteins, resulting in the formation of a high hydrogen ion concentration towards one
side of the membrane. However in order to re-establish the presence of equilibrium, the hydrogen ions must move back to the
opposite side of the membrane. Whilst travelling to the opposite side of the membrane, the hydrogen ions travel through the
protein, ATP synthase, and it is the movement of the hydrogen ions across this protein, which give ATP synthase the energy to
convert ADP into ATP, through the attachment of a third phosphate group. The electron transport chain plays a crucial role in the
production of ATP, whereas glycolysis and the citric acid cycle can each produce two molecules of ATP, the electron transport
chain can produce up to 34!
Aerobic Respiration Versus Anaerobic Respiration
The process of cellular respiration is one that can be categorized into two distinct types, aerobic respiration, and anaerobic
respiration. As the name suggests, aerobic respiration simply refers to respiration which is performed in the presence of oxygen,
where as anaerobic respiration is performed in the absence of oxygen. For the duration of their processes, aerobic and anaerobic
respiration are largely similar, in the sense that they only differ in the final stage of respiration, the electron transport chain.
Once the electrons have completely travelled across the mitochondrial membrane, in the electron transport chain, they bind to a
final electron acceptor at the end of the electron transport chain. In the case of aerobic respiration, this final electron acceptor
happens to be oxygen. However in the case of anaerobic respiration, the final electron acceptor happens to be a molecule other
than an oxygen, this differs with most organisms, for instance, certain bacteria certain residing of ocean floors may use sulfur as
their final electron acceptor.
, The Process of Fermentation
Often times when taking part in strenuous physical activities, our bodies begin to get tired and we start to have difficulty
breathing, this occurs when we’re not getting enough oxygen. As the body cannot perform cellular respiration without sufficient
amounts of oxygen to serve as the final electron acceptor, it resorts to the process of fermentation. As a process, fermentation is
considered to an anaerobic one, as it does not involve oxygen, however this does not mean that fermentation is the same as
anaerobic respiration.
Similarly to cellular respiration, the first stage of fermentation is glycolysis, in which the cell breaks downs a single molecule of
glucose, to form two molecules of ATP and pyruvate. However it is in the second stage where the process of fermentation
differentiates itself from the process of cellular respiration. As oppose to using the molecules of pyruvate to form additional
molecules of ATP, as the cell does in cellular respiration, the pyruvate molecules remain in the cytoplasm, and are used to make
either lactic acid, or ethanol. In the process of fermentation, a whole molecule of glucose is utilized to produce only two molecules
of ATP. It is the production of just two molecule of ATP which makes the process of fermentation so much more inefficient than
cellular respiration, which can be used to make up to 38 molecules of ATP with just one molecule of glucose.
As fermentation results in the production of either lactic acid, or ethanol, which is an alcohol, it is heavily dependant on the type
organism weather or not it performs lactic acid fermentation, or alcoholic fermentation. For instance in the case of humans, only
lactic acid fermentation can be performed, whereas in the case of yeast cells, alcoholic fermentation can be performed, making it
an essential part of the brewing industry.
Purpose
To investigate the affects of oxygen on the rate of carbon dioxide production in yeast cells.
Abstract
The abstract of this lab experiment is to determine affects of oxygen on the rate of carbon dioxide production in yeast
cells, this is to be determined through amalgamation of solutions of deoxygenated yeast cells and glucose suspensions and the
amalgamation of solutions of oxygenated yeast cells and glucose suspensions. The corresponding pressure changes are then to be
determined through the utilization of a PASCO Xplorer GLX and the PASCO Pressure Sensor Kit.
Hypotheis
Subsequently analyzing and examining the biological processes of cellular respiration and fermentation, it is hypothesized
that the rate of carbon dioxide production will be at it’s greatest when the yeast cell suspension undergoes the process of
fermentation with a solution of glucose, whilst in the presence of deoxygenated water. Correspondingly, it is also hypothesized
that the production of carbon dioxide will lower in the solution of the oxygenated yeast and glucose suspension. The most
significantly increased absolute pressure reading would be indicative of the highest rate of carbon dioxide production, as an
increase in carbon dioxide production, is directly associated with an increase in absolute pressure.
This hypothesis was drawn from the fact that amalgamation of solutions of deoxygenated yeast cells and glucose suspensions
would result in the occurrence of the metabolic process of ethanol fermentation, which releases ethanol and carbon dioxide as it’s
final by products. Unlike aerobic respiration, which is to be conducted through the amalgamation of solutions of oxygenated yeast
cells and glucose suspensions, ethanol fermentation is performed in the absence of oxygen and primarily utilizes it’s glucose
molecules in the production of ethanol and carbon dioxide. However in the case of aerobic respiration, the glucose and pyruvate
molecules are predominately utilized in the formation of it’s final products, water and ATP molecules, with carbon dioxide
molecules only being produced as side products.
Variables
The independent variable happens to be wether or not the amalgamation of solutions of yeast cells and glucose
suspensions are to be conducted in deoxidized or oxidized water solutions, this in turn impacts the rate at which the carbon
dioxide gas is produced. The dependant variable happens to be the rate at which the carbon dioxide is produced in the yeast cells.
Additionally, to ensure results of the highest accuracy, certain controlled variable have also been implemented, such as the 8%
yeast suspension, 10% glucose solution concentration and, a constant temperature throughout the duration of the reactions (40°C).
Materials and Apparatus
• Lab Gown
• Lab Safety Goggles
• PASCO Pressure Sensor Kit
• PASCO Temperature Sensor Kit
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