Topic 2 & Some Topic 8 Part 1: Molecular Biology/ Metabolism & Cellular Respiration Flashcards
DP2- U3- Metabolism & Cellular Respiration
A. Metabolism
1.Define metabolism.
The sum total of all chemical reactions that occur within an organism.
A. Metabolism
2.Outline the three common patterns of metabolism.
1: Most chemical changes happen not in one large jump but in a sequence of small steps (biochemical Pathways)
2: most metabolic pathways involve a linear change of enzyme-catalyzed reactions
3: Some metabolic pathways involve a cycle of enzyme-catalyzed reactions where the end product of one reaction is the reactant that starts the rest of the chemical pathway. Ex. Calvin cycle
A. Metabolism
3.Explain how enzymes affect activation energy and illustrate using a graph.
what is Ea, how do enzymes effect, transition point?
- Activation energy is the initial input of energy that is required to trigger a chemical reaction.
- When the substrate binds to the enzyme’s active site, it lowers the activation energy threshold by binding the substrate to the active site, the bonds in the substrate are weakened, thus lower Ea and are easily broken.
- The transition state is the point (also seen on the graph-vertex) where the reactants are all converted into products the amount of energy needed to reach the transition state Is overall lowered when using an enzyme/catalyst.
- However, the amount of energy released by the reaction is unchanged
- Enzymes speed up the rate of reaction to be 1 mill x faster
know the graph too
A. Metabolism
4.Contrast competitive and non-competitive enzyme inhibition providing an example of each.
defn, effect on ROR if inihibtor is increased, max ROR effect, ex.
Defn: An inhibitor is a molecule that binds to an enzyme and slows down or stops an enzyme’s function
Competitive:
* An inhibitor that fits into the active site and prevents the substrate from entering
* The higher the concentration of the inhibitor, the slower the ROR. this is because there are more inhibitors per enzyme- so the chances of the substrate binding are slim.
* Even with competitive inhibition, the same max ROR will be achieved if more substrate is added– this is because the number of enzymes are still the same.
* Ex. Antabuse for combating alcoholism.
It competes with the aldehyde oxidase enzyme by preventing the acetaldehyde from being converted to acetic acid
* ethanol (oxidation) –> acetaldehyde (adehyde oxidase+antabuse INHIBITOR) –> X acetic acid X
* The buildup of acetaldehyde follows resulting in a strong feeling of nausea and other strong hangover symptoms
* Antabuse is administered as a daily pill and its effectiveness relies on the user
Non-competitive:
* An inhibitor that fits onto the allosteric site causes a conformational change in the enzyme’s active site therefore the substrate cannot attach and react.
* The higher the concentration of the inhibitor, the slower the ROR. this is because there are fewer functional active sites available.
* The max rate of reaction is reduced. With fewer functional active sites the enzyme has reduced its ability to process the substates, even if the substrate concentration is increased.
Ex. ACE inhibitors for helping control blood pressure
* The RAA system causes vasoconstriction (tightening blood vessels) when blood pressure drops (such as after heavy bleeding)
* the production of angiotensin can make the vasoconstriction problem worse in those with hypertension or heart failures.
* ACE inhibitors are medications, given to those with hypertension etc., that inhibit angiotensin-converting enzymes– they prevent increased blood pressure and vasoconstriction by directly influencing the production of angiotensin II.
A. Metabolism
5.Distinguish different types of inhibition from graphs at specified substrate concentration.
Competitive inhibition- same max rate, different rate of reaction initially:
* The substrate and the inhibitor are competing to bind to the active site
* Slows the rate of reaction (uninhibited has a steeper logarithmic slope compartvley)
* However, the max rate of the uninhibited enzyme can be achieved with the competitive inhibitor once the substrate concentration significantly exceeds the amount of inhibitor.
* Thus, it takes a much higher substrate concentration to achieve the same max rate of an uninhibited enzyme.
Non-competitive inhibitors- different max rate and rate of reaction:
* Both the substrate and inhibitor are not competing for the same site on the enzyme
* The binding of the non-competitive inhibitor reduces the number of enzymes that can catalyze the reaction regardless of the substrate concentration- since it changes the conformation of the active site.
* The enzymes that are not binded to the inhibitors work normally to produce the same rate of reaction and substrate concentration curve.
* Therefore, the rate of reaction is heavily decreased (because of the conformational change) and so is the Vmax
* The Vmax is achieved at around the same time as the uninhibited enzyme, however, it is just lower.
know the graphs
A. Metabolism
6.Explain end-product inhibition using the conversion of threonine to isoleucine as an example.
End-product inhibition: prevents a large build up of products by using a product to bind to the allosteric site of the initial enzyme– creates a conformational change.
Example: threonine to isoleucine
* Bacteria synthesizes isoleucine from theonine in a series of 5 enzyme catalyzed steps– creates 4 intermediates
* As this enzyme catalyzed reaction continues to occur in the body– to many products may be formed for the body’s use– unnecessarily using energy to create
* Therefore, as the concentration of isolecuine increases, some of it binds to the allosteric site of threonine deaminase which is the first enzyme used in the pathway.
* As such, the isoleucine acts as a non-competitive inhibitor to the threonine deaminase resulting in the pathways to be turned off- regulating the production of more isoleucine
* If the concentration of isolecuine later falls (as a result of its use) then the allosteric sites of the theornine deaminase are emptied and the enzyme catalyzed reaction to create more isoleucine from threonine recommences.
* This is an example of a negative feedback loop- when a stimulus causes a response that reduces the initial stimulus)
graph on doc
A. Metabolism
8.Calculate and plot the rates of reaction from raw experimental data.
did this in the lab
B. Cellular Respiration
9.Define cell respiration
The controlled release of energy from organic compounds in cells to form ATP
* The controlled release of energy: controlled through enxymes (metabolic pathways and cycles, and through end-product formation)
* ATP is not transferred from cell to cell and all cells require a continuous supply of energy.
-These are the reasons why cell respiration is an essential process for all cells.
* If it was not controlled much of the energy from ATP that is used in cells is ultimately converted to heat and lost to the environment- causing death.
B. Cellular Respiration
10.Outline the function of ATP
where is it used, where/how formed/deformed, advantage
- ATP is used for energetic processes like muscle contraction, active transport, DNA/RNA replication, protein synthesis, vesicle transport, etc.
- ATP is stored in the special nucleotide which is found in the bonds between the phosphate groups. Their phosphate groups are negatively charged but crowded together- this mutual repulsion makes the triphosphate chain of ATP potential energy.
- Advantage is that energy is immediately available. By cellular respiration, the ADP and phosphate can be converted back to ATP after it is broken for energy usage.
- It is formed by a phosphorylation reaction- addition of a phosphate group to an organic molecule, in this case, adding a phosphate group to adenosine diphosphate to create adenosine triphosphate
-This is an endergonic/ endothermic anabolic reaction- input of energy and stores that energy in the ATP molecule. - It is broken down by a dephosphorylation reaction- removal of a phosphate group from an organic molecule
-Example of an exergonic/exothermic catabolic reaction because it reaction that releases energy
-By the end a net of 36 ATPs (on average) are produced from one molecule of glucose (if there is oxygen).
B. Cellular Respiration
11.Outline anaerobic respiration
defn, anaerobes?, fermentation 2 types
• Anaerobes are organisms that derive all their ATP without oxygen
• Anaerobic respiration is respiration in the absence of oxygen- anaerobes use this
• fermentation is the anaerobic way to breakdown glucose for ATP production
• Two main types of fermentation: alcoholic fermentation and lactic acid fermentation
• Yeast uses alcoholic fermentation and humans use aerobic respiration but resort to lactic acid fermentation when there is not enough oxygen in their cells
B. Cellular Respiration
12.Outline the use of anaerobic cell respiration in yeast
bread: yeast effect, how does it respire, why dough rise, diff. product
Bioethanol: defn, produced, how it it kept at optimum, plant to sugars how?, yeast and plants effect, how purfied
Yeast and Bread
* Yeast is used to make bubbles of gas in bread so it is lighter
* The dough is kept warm after kneading so the yeast is encouraged to respire
* The oxygen in the dough is soon used up so the yeast is forced to respire anaerobically instead of aerobically
* The CO2 produced by the anaerobic cell respiration cannot escape from the dough and then forms bubbles causing the dough to swell and rise
* Ethanol is also a product of anaerobic cell respiration but it evaporates during baking
Bioethanol and Yeast
* Bioethanol (ethanol produced by organisms) is a renewable energy source.
* It is produced by sugar cane and maize using yeast
* Fermenters are used to keep the yeast at its optimum condition
* Plant starch and cellulose are broken down by enzymes into sugars
* When yeast carry out anaerobic respiration on the plant material, the sugars in the plant material are converted to ethanol and carbon dioxide
* The ethanol produced by the yeasts is purified by distillation and water is removed to improve combustion.
B. Cellular Respiration
13.Outline lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.
- Anaerobic respiration is used in certain human activities such as weight lifting and sprinting
- Rapid generation of ATP in anaerobic respiration enables humans to maximize the power of muscle contractions
- anaerobic respiration creates lactate- there is a limit to the concentration of lactate the body can tolerate thus tolerating how long anaerobic respiration can be done for.
- Afterwards lactate must be broken down- this requires the use of oxygen. It can take several minutes for enough oxygen to be absorbed for all lactate to be broken down. The demand for oxygen that builds up during a period of anaerobic respiration is called the oxygen debt.
B. Cellular Respiration
14.Contrast anaerobic respiration with aerobic respiration.
aerobic respiration= w/oxygen, greater yield of ATP,
anaerobic respiration= w/o oxygen, rapid supply of ATP as oxygen is not required
B. Cellular Respiration
15.Analyze results from experiments involving respirometer respiration rate data.
PRACTICE PROBLEMS WITH DATA AND CHARTS!
* Respirometers measure the rate of respiration by measuring the consumption of oxygen
* Aerobic respiration uses 6 molecules of oxygen gas and creates 6 molecules of carbon dioxide gas. Therefore there is no change in volume but the carbon dioxide is absorbed thus the volume of gas in the respirometer decreases.
Material Function:
* Absorbent cotton & rayon: chemically absorbs the CO2 produced by the respiring organism by the cotton being saturated in KOH (not enough to kill the peas), thus increases the efficiency of the CO2 absorption. The rayon is used to protect the respiring organism from that strong base.
* Potassium hydroxide (alkai) solution: hydroxide solutions are used to absorb cotton dioxide in the air
* Respiring organism (peas): suitable living organism that will respire aerobically
* Capillary tube with a rubber stopper: help read the change in gas for respiring organisms. One entrance allows for control of exposure to air
* Plastic beads: testing the cellular respiration effect
Simple method:
* Capillary tube with rubber stopper inserted in a glass container.
* Layer of saturated KOH cotton is placed in the bottom with the rayon layered on top
* One sample has the germinating seeds and one has the plastic beads. Another can be tested with half non germenating peas and half plastic beads. Ensure they are all of the same volume with water displacement in a graduated cylinder.
* Add petroleum jelly to the edges of the rubber stopper to ensure it is sealed for any leaks. If there are leaks the water would not move accordingly.
* The three respirometers are then placed in a narrow width of a water bath ontop of masking tape so the end of the capillary tubes are above water
* Leave for 7 minutes for equilibrium of respirators to the temperature of the water
* Then submerge the tubes entirely into the water bath
* Read the movement of the water air bubble throughout the capillary tube
* The germinated beads should have a difference. The plastic and half and hald should not change due to no cellular respiration.
Temperature effect:
B. Cellular Respiration
16.Outline the ethical considerations of using invertebrates in respirometer experiments.
4
- Germinating seeds can demonstrate most aspects of respirometer use rather than an animal.
- The placing and confinement of an animal in a respirometer tube could harm or damage the animal.
- Exposure to the alkali (that absorbs carbon dioxide) must be completely avoided as it may harm the animal.
- The habitat and place the animal was taken from should be noted and then it can be returned to the natural habitat.
