Obligate anaerobes are organism that cannot live with the presence of oxygen, meaning they live without oxygen and cannot survive with the presence of oxygen. If to compare with obligate aerobes on the other hand, obligate aerobes only can live with the presence of oxygen. According to the question, facultative anaerobes can live in both condition, which is with or without the presence of oxygen. An example of obligate anaerobe is clostridium tetani (tetanus). An example of facultative anaerobe is vibrio cholerae (cholera).
clostridium tetani bacteria
vibrio cholera bacteria
(source- nelson's biology page 92)
(image source - google images)
5. Clostridium species include bacteria that produce serious infections in humans.
(a) Are Clostridium species obligate aerobes, obligate anaerobes, or facultative anaerobes? Explain.
Clostridium species are obligate anaerobes. This means that they cannot live with the presence of oxygen.
(source - biology-online.org)
(b) What waste products of energy metabolism do Clostridium species excrete?
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Waste products of energy metabolism that Clostridium species excrete is toxins.
(source - microbewiki.kenyon.edu)
(c) Describe three infections in humans caused by Clostridium species.
The three infections in humans that is caused by Clostridium species are clostridium perfringens, clostridium clostridioforme, and clostridium tertrium. Clostridium perfringens is related to gastrointestinal disease. Clostridium clostridioforme is related to liver abscess. Clostridium tertrium is related to brain abscess.
(source - wwwnc.cdc.gov)
6. How do ADP and ATP differ in structure? In free energy content?
The structure of ATP or also known as Adenosine Tri-Phosphate has 5 carbon ribose sugar. It is a small molecule. It is also nitrogenous based. Based on it's name which is obvious, it has 3 phosphates. As for the structure for ADP or also known as adenosine diphosphate. The difference is that adesonice diphosphate has 2 phosphate compared to ATP which has 3 phosphates. From my understanding, these molecules release energy when everytime a phosphate is removed from the structure. For an example when the outer most phosphate atom is released from the tri-phosphate structure, free energy is released. From this process also, the molecule becomes adenosine diphosphate or ADP. If another phosphate is released from ADP, free energy will be released again. When this happens, the molecule structure will only have one phosphate, so it will be named adenosine monophosphate or AMP. The rate of energy released when ATP is converted to ADP from the process of removal of the phosphate is about 30.5KJ/mol. In the human body, the total amount of ATP + ADP will always be at constant rate because it is converted from ADP to ATP or vice versa constantly.
This picture shows the conversion of ATP to ADP.
(source and image source - biologysuccess.hubpages.com)
7. Arrange the following types of cells in order of increasing number of mitochondria in the cytoplasm: nerve cell, skin cell, fat cell, heart muscle cell. Provide a rationale for your sequence.
According to my opinion, the least most number of mitochondria in the cytoplasm is the fat cell. This is because there is no significance movement of the body, and the function of the fat cells is just to store fat. Therefore, not much of energy is needed for this process. The second most number of mitochondria in the cytoplasm is the skin cell. Again, the skin cells do not require much energy. The third most number of mitochondria in the cytoplasm is the nerve cell. The nerve cells require a significant amount of energy because it transfers nerve impulse throughout the body along the spinal chord and periphery system at very fast rate. It requires information to be transferred at the synapse from the brain to the rest of the body and vice versa. The most number of mitochondria in the cytoplasm has got to be the heart muscle cell. The heart is the primary or the most important muscle in all our system. Without the function of the heart, a person cannot live. This is because the hearts role to pump the oxygenated and deoxygenated blood through our body at very high pressure. In order to pump the blood throughout the body, the heart muscle needs great amount of constant energy source, which in this case is the mitochondria.
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9. (a) Why is every reaction of cellular respiration catalyzed by a specific enzyme?
Enzyme is a protein catalyst and is found throughout the human body. Enzyme plays an important role to make sure that every process is carried out. Basically, if there are no enzymes, no process will take place. Each enzyme is specific to its reactants and its process. For an example, enzyme related to cellular respiration do not catalyze reactants for reproduction processes, cardiovascular enzymes do not react or bind with hormonal production enzyme, and so forth. So, each enzyme has its own role and do not mixup with each other. This can be described by the term 'lock and key'. The enzymes ensures that each cellular respiration process happens on time , and also in order.
(b) What would happen to an organism that lacked the gene for hexokinase, the enzyme that catalyzes the first reaction in glycolysis?
The first step in glycolysis is already the phosphorylation of of glucose by the enzyme called hexokinase. This is the first step, hence it plays the most important role. So, if an organism lacks the gene for hexokinase, my opinion is that the cellular respiration would not likely to happen.
(source - flashcardexchange.com)
10. Describe the function of NAD and FAD in cellular respiration.
NAD and FAD has important role in the process of glycolysis, pyruvate oxidation and the Krebs Cycle as it co-relates with each other. NAD which also is known as nicotinamide adenine dinucleotide and FAD which is also known as flavin adenine dinucleotide. NAD functions in oxidative phosphorylation by removing two hydrogen atoms which consists of two protons and electrons. NAD is used to shuttle the electrons to the first component. So when two hydrogen atoms is removed, two electrons and a proton is then attached to NAD and then it becomes NADH. NADH is already oxidized, meaning the oxygen atoms are removed. FAD also function almost the same like NAD. Like NAD, FAD also remove two hydrogen atoms and becomes FADH. This process happens in the Krebs cycle. When NAD and FAD is reduced to become NADH and FADH, it actually releases energy which is transferred to the ATP molecules. Below is a diagram of the Krebs cycle.
(source - nelson's biology page 96-105)
(image source - googleimages)
12. Why is aerobic respiration a more efficient energy-extracting process than glycolysis alone?
Well, first of all, if we see in numbers, aerobic respiration produces about 36ATP meanwhile glycolysis produce only 2 ATP. From these numbers, in can be concluded that aerobic respiration is more efficient energy-extracting process than glycolysis. This is because during glycolysis, only about 2% of the energy is being harnessed. As for aerobic respiration, the energy harnessing process is more thorough and complete. In fact, by the end of the krebs cycle, the whole glucose structure is broken down and all the energy is harnessed into ATP's.
(source - edurite.com)
18 (a) Distinguish between metabolic rate and basal metabolic rate.
According to Nelson's biology, the metabolic rate is defined as the amount of energy consumed by an organism at a particular time. Basal metabolic rate or BMR is defined as the minimum energy that is required by an organism to survive.
(source- nelson's biology page 110 and 111)
(b) Explain how and why metabolic rate changes as we grow older.
Metabolism is often associated with one's weight or rate of weight gaining. This is also correct. Metabolism is actually very wide and is often defined as the rate of chemical process in our body. Different individuals have different metabolic rate. When we are young, our body is in our prime state. Our muscles are strong. Our bones are tough, we carry out daily activities which consumes alot of energy. Actually, metabolic rate fluctuates regularly depending on the person's daily physical activity. If a person's daily activity is rigid and requires alot of energy, the metabolic rate will be higher. This means that the rate of chemical process that occur in the body will be of greater speed. All the production of hormones and other processes will be faster. Now back to the question, as we grow older, our metabolic rate is actually becoming lower. The term for this is declining in efficiency. This will normally lead to death of the time once the body has completely been broken down, meaning the bodily functions becoming absolutely zero. The main source of energy is in the form of ATP. As we know, ATP requires oxygen. As we age, our respiration rate becomes slower. When our respiration rate becomes slower, hence, the production of ATP's will decrease. This will lead to energy insufficiency. Another source of energy is from carbohydrates and other nutrients. As we grow older, our digestion function tends to become less optimum. This will result in poor digestion of the nutrients to supply energy. When the energy is less, the metabolic rate will become less as well. Basically, all of these points that I have given relates to the changes of the metabolic rate as we grow older.
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