BIOD 171/ BIOD171 Microbiology Lecture Exam Key 1-6

1. True or False: A virus is considered a microorganism. False. Viruses are not living and as such are not considered microorganisms. Viruses can, however, be classified as microbes, a more general term that includes microorganisms and viruses. 2. What is the smallest biological unit of life? A cell. 3. At a generalized level, all cells are comprised of what? Macromolecules* *A student may also answer: Proteins, Lipids, Nucleic acids and Polysaccharides but they must answer with all four to be fully correct. 1. How many different types of amino acids are available from which to make proteins? 20 2. Define an essential amino acid. An essential amino acid cannot be produced by the human body and as such must be take in from the environment through alternative sources (i.e) food. 1. What are the two major types of nucleic acids and their roles? DNA- deoxyribonucleic acid RNA- Ribonucleic acid DNA- Cellular life has DNA and a role that DNA has is long-term storage of information, it holds the characteristics of living organisms. RNA- Is the carrier of information in form of amino acid sequence. It converts the information in the DNA and synthesizes proteins1. Complete the following DNA strand and indicate how many bonds are formed for each complementary pair: 3’ GGTCATCG 5’ 5’ CC AGC 3’ 3’ GGTCATCG 5’ 5’ CCAGTAGC 3’ There are 2 bonds formed between A and T, and 3 bonds between G and C. 1. The plasma membrane (select all that are true): A. Restricts movement of materials in and out of the cell B. Is often a triple layer comprised of lipids C. Prevents essential nutrients from escaping D. Contains hydrophobic tails pointing outward A and C 2. How many carbon atoms are present in the monosaccharide glucose? A. 1 B. 3 C. 6 D. 12 C. The molecular formula of Glucose is C6H12O6 True of False: The genetic material within a prokaryotic cell is contained within a membrane-enclosed region. False. Only eukaryotic cells contain its genetic material within a nucleus True or False: Prokaryotic cells can be subdivided into Bacteria and Archaea. TrueDescribe the 4 basic bacterial morphologies. Coccus (round/spherical), bacillus (rod), vibrio (curved rod) or spirillum (spiral/corkscrew). True or False: Archaea is noted for its ability to survive under harsh conditions. True. Archaea can often be found in harsh conditions such as high salt levels, high acid conditions, high temperatures and even oxygen-poor conditions. 1. Which of the following microorganisms are considered to be Eukarya? Select all that apply. A. Animalia B. Plantae C. Fungi D. Protista A,B,C,D 2. True of False: All multicellular microorganisms classified as Animalia are heterotrophic. True 3. Microorganisms classified as Plantae obtain most of their energy by converting _____ energy into _______ energy. Light (sunlight); chemical (sugars) 1. A defining characteristic of fungi is the presence of chitin in the cell walls. Which of following also contain chitin? Select all that apply. A. Mushrooms B. Bacteria C. Yeast D. Molds A, C and D all contain chitin. 2. True or False: A defining characteristic of Protista is the inability of colonies to form tissue layers. True.1. Cell walls are found in which of the following (select all that apply): A. Plants B. Fungi C. Bacteria D. Mammalian cells E. Algae A, B, C, E 2. The function of the ribosome is (select all that apply): A. Lipid synthesis B. Protein synthesis C. To produce energy (ATP) D. Protein modification and distribution E. Waste disposal via hydrolytic enzymes B. Ribosomes are located in the cytoplasm of prokaryotic cells and in the ER of eukaryotic cells. 1. Identify the following cellular components by matching the number with the description. A. Cell wall B. Lysosome C. Centriole D. Rough endoplasmic reticulum E. Plasma membrane F. Nucleus G. Golgi apparatus1 F 2 B 3 E 4 G 5 D 1. True or False: Metabolism is a controlled set of biochemical reactions that occur in living organisms in order to maintain life. True. 2. True or False: Enzymes are polysaccharides that catalyze chemical reactions. False. Enzymes are proteins that catalyze chemical reactions. 3. What are usually metal ions known to assists enzyme during the catalysis reaction? Cofactors are usually metal ions and assist enzyme during the catalysis reaction. 1. Define catabolism. Catabolism is the process of breaking down larger molecules into useful energy sources. 2. Upon cellular injury, which metabolic process is involved during the growth and repair phases of the cell? The anabolic process would be active as it (by definition) is involved in the building up of small complexes into larger complexes. 1. Describe the energy transfer process relative to both ATP and ADP. ATP has the energy (phosphate group) to donate while ADP can accept energy in the form of a phosphate group. Thus, ATP can be reduced (ATP →ADP + Pi) while ADP can be built into ATP (ADP + Pi →ATP). 2. An organism that derives its energy (generates ATP) from photons of light is called a _________? Phototrophic microorganism. An organism that derives its energy by removing electrons from elemental sulfur would be classified as a __________?Lithotroph 4. A reactive intermediate would be present in which phosphorylation process? A. Photophosphorylation B. Substrate-level phosphorylation C. Oxidative phosphorylation B. The chemical compound losing the phosphate group is referred to as the phosphorylated reactive intermediate. 1. The catabolism of a single molecule of glucose goes through what 3 distinct transitions? The breakdown of glucose goes through (1) Glycolysis then (2) Fermentation or Respiration and finally through (3) the electron transport chain (ETC). 2. What is the most energetic transition in the catabolism of glucose? The electron transport chain yields 34 ATP while both glycolysis and fermentation (or respiration) each yield only 2 ATP. 3. Identify the reactants of the following chemical equation: Glucose + 2NAD+ → 2 NADH + 2 Pyruvate + 2 ATP The reactants are to the left of the arrow: Glucose and 2NAD+ 4. The presence of what molecule ‘signals’ to the cell that glycolysis is about to start? Glucose-6-phosphate (G6P) 5. True or False: In the absence of oxygen fermentation produces 2 ATP. False. Fermentation only reduces NADH back to NAD+ 1. What is the primary byproduct of the TCA cycle? Select all that apply. A. NAD+ B. FADC. NADH D. FADH2 C and D. The TCA cycle produces an abundance of reduced electron carriers (NADH and FADH2). 2. True or False. The reactants of the TCA cycle directly enter and fuel the electron transport system. False. The products of the TCA cycle (reduced electron carriers) enter and drive the production of ATP via the electron transport system. 1. In the absence of glucose, which of the following can be used as alternative energy sources? Select all that apply. A. Lactose B. Nucleic acids C. Carbohydrates D. Lipids A, C, D can all be used as alternative energy sources. 2. For the catabolism of proteins and lipids, which of the following enzymes are used? Select all that apply. A. Ligases B. Proteases C. Transferases D. Lipases B and D. Proteases breakdown proteins while lipases breakdown lipids. 3. True or False. The β-oxidation pathway catabolizes the fatty acid chains of lipids. True 1. Describe the relationship between chloroplasts and chlorophyll. Both chloroplasts and chlorophyll are associated with photosynthesis. Chloroplasts are the double membraneenclosed organelles that contain the photosynthetic pigment chlorophyll. 2. True or False: Chloroplasts are specific to algae and plants. True3. The process of photophosphorylation produces which of the following: select all that apply. A. ATP B. Glyceraldehyde-3-phosphate C. CO2 D. NADPH E. H2O A and D. 1. In phosphorylation, the light reactions always occur where? The process of converting light energy into chemical energy (photophosphorylation) always occurs in the membrane. 2. True or False: The Calvin cycle must occur in the absence of light. False. The term ‘dark reactions’ (also known as the Calvin Cycle) simply denotes the second stage in photosynthesis—dark reactions do not actually require darkness in order to occur. 1. How many turns (or repititions) of the Calvin Cycle are required to generate one molecule of glucose? Six. 2. Complete the following equation by placing the appropriate numbers where indicated. __CO2 + __ATP + __NADPH + __H20 → __C6H12O6 + __ADP + __NADP+ 6 CO2 + 18 ATP + 12 NADPH + 12 H20 → C6H12O6 + 18 ADP + 12 NADP+ 1. Match the following reactions to its corresponding enzyme: 1. A-B + H2O → A-OH + B-H 2. A-B→ B-A 3. A + B → A-B 4. A-B → A + B A- Lyases B- TransferasesC- Oxioreductaces D- Hydrolases E- Ligases F- Isomerases 1D 1. A-B + H2O → A-OH + B-H Hydrolases 2F 2. A-B→ B-A Isomerases 3E 3. A + B → A-B Ligases 4A 4. A-B → A + B Lyases 1. A micrometer is defined as A. 10-3 B. 10-6 C.10-9 D. 10-12 B. A micrometer is one-millionth of a meter. 2. True or False: A nanometer is longer than a micrometer. False. A nanometer is 1,000 times smaller than a micrometer. 1. Resolution and contrast are two critical factors that influence your ability to see an object. Explain each. Resolution refers to the distance between two objects at which the objects still can be seen as separate. Poor or low resolution means two (or more) objects may appear as one. Contrast is the difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult. For instance, trying to identify 2 dark colored objects at night (low light = low contrast) versus the same 2 objects in the middle of a sunny afternoon (bright light against 2 dark objects = high contrast). 1. Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample. A. Objective B. Condenser C. Iris diaphragm D. Eye pieceA. Only the oculars (eyepiece) and the objectives contribute to the magnification of the sample. Since the eyepiece is fixed, only the objectives could be altered. 2. What is the total magnification (relative to your eye) of a sample imaged with a 20x objective and a 15x eyepiece? Show your math. 20 x 15 = 300x magnification 1. True or False: Staining is often required to image a cell that is adherent and flat (thin). True. Adherent, flat and unstained cells are almost invisible due to the limits on both resolution and contrast. Therefore, cell staining is often required to adequately image the sample. 2. Which of the following could NOT be seen clearly by the unaided eye? Select all that apply. A. Bacteria with diameter of 24 μm B. Protozoa with diameter of 150 μm C. Virus with a diameter of 0.2 μm D. Skin cell with diameter of 1500 μm A and C. The unaided eye can, on average, clearly resolve objects 100 μm 1. Label the following unmarked microscope components (numbered arrows) by matching it with the components provided (letters)