LEVEL 1
The electron transport system in bacteria is located on the _________ and in eukaryotic cells on the ________.
a. plastid, chloroplast
b. cytoplasmic membrane, mitochondria
c. cell wall, mitochondrion
d. mitochondrion, cytoplasmic membrane
cytoplasmic membrane, mitochondria
Enzyme action can be blocked by competitive molecules binding in the active site, by repressors binding in a distant site, and by
a. product binding to the DNA used to make enzymes
b. substrates being in high concentration
c. incorrect temperature conditions
d. two of the above
Two of the above... which two?
Why does glycolysis, which is the beginning point of many catabolic pathways, not require oxygen?
Evolutionarily, glycolysis is an ancient pathway that developed before photosynthesis, which added oxygen to the atmosphere and became common. Since glycolysis does not require oxygen, it is anaerobic, and its purpose is to turn glucose into pyruvic acid. If oxygen was present, the pathway would continue to the Krebs cycle and oxidative phosphorylation.
Compare and contrast the molecular structure of ATP with the molecular structure of an RNA nucleotide.
ATP is a single nucleotide. An RNA nucleotide is made up of ribose sugar, nitrogenous bases, and one phosphate group. They both contain ribose sugar, an adenine nitrogenous base, and a phosphate group. RNA molecules also contain the base uracil instead of thymine.
Contrast the creation of lactic acid in human cells via fermentation with microbial fermentation.
Lactic acid is a byproduct of fermentation when the body needs a lot of energy in a hurry, such as sprinting. Once stored ATP is used, human cells produce additional ATP through lactic acid fermentation. In low oxygen conditions, glycolysis can continue to produce ATP by converting pyruvate to lactic acid, which regenerates NAD+. The lactic acid built up during the fermentation cycle limits the amount of fermentation that can occur. Microbial fermentation differs in that distinct sets of enzymes are used for the formation of complex mixtures of byproducts that can be characterized by smell and taste. One example would be the fermentation of alcohol, in which ethanol and carbon dioxide are byproducts, rather than lactic acid.
Many coenzymes are formed from
a. metals
b. vitamins
c. proteins
d. substrates
Vitamins
The type of microbial metabolic pathway that is most often exploited to make acids and alcohols industrially is
a. aerobic respiration
b. anaerobic respiration
c. fermentation
d. none of the above
Fermentation
Describe the roles played by ATP and NAD in metabolism.
NAD is responsible for being an electron acceptor. It carries the electrons to the electron transport chain which then synthesizes ATP. ATP then provides energy for other functions in organisms/ cells.
Find three enzymatic capabilities commonly used to identify microbial species in a clinical lab.
1) carbohydrate hydrolysis: Starch is broken down and hydrolyzed by bacteria and used as a source of carbohydrates (contains enzyme diastase)
2) Protein hydrolysis: Proteins are hydrolyzed into peptide bonds and amino acids by some bacteria, which are used as energy sources (protease assists with this mechanism) We have done gelatin or collagen hydrolysis in lab.
3) Catalase oxidation: some bacteria break hydrogen peroxide into water and free oxygen (catalase aids with this process)
Polymerase chain reaction (PCR) is a lab technology that requires high temperatures to make copies of DNA. The copies are made using an enzyme called a polymerase. PCR would not have been possible before thermophilic archaea were discovered. Explain why.
Thermophilic archaea are microorganisms that thrive in extreme environments, including high temperatures. Following research, scientists found that some of the archaea contained a unique DNA polymerase enzyme that allowed them to withstand high temperatures and resist denaturing themselves. This stability during high temperatures has allowed scientists to efficiently replicate DNA. PCR techniques used today utilize the "Taq polymerase" which is a thermophilic bacterial species.
Energy is carried from catabolic to anabolic reactions in the form of
a. ADP
b. high-energy ATP bonds
c. coenzymes
d. inorganic phosphate
high-energy ATP bonds
Which of the following is true?
a. The suffix “-ase” indicates an enzyme
b. Often enzymes are named for the substrates they act upon
c. Enzymes are larger than their substrates
d. All of the above are true
All of the above are true
What is meant by the concept of the “final electron acceptor”?
A final electron acceptor is a molecule that acquires the electrons last in the electron transport chain. Usually insists that the final electron acceptors have a high electronegativity that can accept electrons with low energy. In aerobic respiration, oxygen is the final e- acceptor. In anaerobic respiration, the final e- acceptor can be a variety of other inorganic molecules. (nitrate reduction, H2S production in lab!)
Explain why electron transport systems are always found in a membrane.
They are always found in a membrane because the ETC produces a proton concentration gradient. The gradient then ignites ATP synthesis. This allows it to grab the high-energy electrons and use them to integrate hydrogen ions.
Provide evidence in support of or refuting the following statement: The evolution of aerobic respiration was driven by the success of photosynthetic microbes.
The first organism to begin producing oxygen by splitting water and using the electrons/ protons in the ETC to produce ATP was cyanobacteria. Its path is comparable to eukaryotic photosynthesis. The oxygen produced forced a selectiveness on anaerobic organisms that had learned to function in the presence of oxygen. It was then proven that these anaerobic organisms could function more efficiently if oxygen was used as the final electron acceptor.