2. The medium contains 10 times as much lactose and sucrose as
glucose. Bacteria that ferment glucose produce a wide variety of
acids, turning the color of the medium from red to yellow. When any
sugar is metabolized under anaerobic conditions (fermentation),
there is increased acid production, thus the butt of the tube
remains acid for a longer period of time. When glucose only is
fermented, acid is produced throughout the medium but due to the
relatively low concentration of glucose in the medium and the
aerobic metabolism that is present on the slant, nitrogenous
metabolic end products soon change the reaction of the slant to
alkaline. These alkaline products neutralize the small amounts of
acids present in the slant but are unable to neutralize the large
amounts acid present in the butt. Thus, the appearance of an
alkaline (red) slant and an acid (yellow) butt after 24 hours
incubation indicates that the organism is a glucose fermenter but
is unable to ferment lactose and sucrose. Bacteria that ferment
lactose or sucrose (or both), in addition to glucose, produce such
large amounts of acid that the oxidative deamination of protein
that may occur in the slant does not yield enough alkaline products
to cause a reversion of pH in that region. Thus, these bacteria
produce an acid slant and acid butt .
3.To detect the fermentation of carbohydrates by change of the
medium from an orange-red to a yellow color.
-phenol red pH 7,
changes to yellow at slightly acidic 6.8
4. A substrate for hydrogen sulfide production. Terminal electron
acceptor, reducing bacteria to sulfide and H2S .
2 Explain why the TSI medium contains a lower concentration of glucose than of lactose and...
Background Background continued... Questions Experiment 2: TSI The triple sugar iron agar (TSI) can identify gram negative bacteria based on how they metabolize carbohydrates. It contains three carbohydrates-glucose, lactose and sucrose, in addition to sodium thiosulfate which some bacteria use in the production of hydrogen sulfide (H2S). It also contains iron in the ferrous form and phenol red as a pH indicator. TSI is poured into a tube when heated to a liquid form, and the tube is slanted as...
Questions 1. What does the term IMVIC mean? 2. Why is the IMVIC useful in identifying Enterobacteriaceae? Are further biochemical tests necessary for complete identification? 3. What diagnostic test differentiates Proteus and Providencia species from other Enterobacteriaceae? om other Enterobacteriaceae 4. How is E. coli distinguished from P. vulgaris on MacConkey agar? On a TSI slant? 5. Instead of TSI, why would a slant medium containing only dextrose and lactose (not sucrose) be preferable for detecting Y enterocolitica? Name such...
Question 5 Explain why lactose has 2 anomeric forms of lactose but, no anomeric forms of sucrose have been recognized? Draw the 2 anomeric forms of Lactose! Question 6 what is the difference between hemiacetal and a glycoside? DRAW AND EXPLAIN
Format 192.168.12 Tools Table Window Help o 5 0 Home Insert Draw Design Layout Times New R. 12 . A- A B TUXX google.cc Oxidation and Reduction Enzymes References Mailings Review View A A A TEE . . . .A .A . NYCD Paste A. . + . . Some media are designed to give multiple test results. Examples include: 1. K ler's Iron agar slant which determines Glucose and Lactose fermentations and production of Hydrogen sulfide 2. SIM which...
4&5 please 4. Juan is a new lab tech who needs to inoculate agar slants that students will be using to make endospore stain smears. He inoculates the tubes on Monday for a lab the following day. Did the students find endospores on their slides? Explain why or why not. 1 point 5. After inoculating with her unknown, Letitia's Phenyl Red Glucose, Lactose, and Sucrose tubes are all yellow. Her TSI tube results are K/H2S. The EMB plate result is...
Use your answer to question 2 to explain why testing for glucose concentration is a good indication of lactase activity on all of those substrates. 4 Convert 37°C to the corresponding value in Fahrenheit. Why do you think most of the experiments in this lab are conducted at 37°C?
Quiz 10 1. (2 points) Which of the following conditions would lead to the highest levels of lac operon expression? a) High lactose, high glucose b) High lactose, low glucose c) Low lactose, high glucose d) Low lactose, low glucose e) None of the above would have any lac operon expression 2. (2 points) Which of the following is true concerning molecular genetics? a) tRNA carries amino acids into the nucleus in eukaryotic cells b) DNA polymerase moves towards the...
(2 pts) You are studying lactose metabolism and have been culturing E. coliin different medias. One media has only glucose, one has only lactose, and a third has both glucose and lactose. (1 pt)You notice that some of the cultures grown in the presence of both glucose and lactose are metabolizing lactose. Which type(s) of mutation(s) could cause this to occur? (1 pt)You notice that some E. colicultures failed to grow in the presence of only lactose. You know that...
1. if given unlabeled samples of glucose, malfose and lactose how could you identify each of the unknown? support your answer with test- glucose steips and barfoeds test. 2. how would glucose, maltose, lactose, lactose +acid, and lactose+ base react with an maltase pill? explain the levels of glucose. 3. starchws and fiber are two other sources of carbohydrates. How do they differ from sugars? 4. With the addition of a lactase enzyme glucose and maltose reacted but lactose did...
Reducing and Nonreducing Carbohydrates 6. Carbohydrate Color after Benediet's AssayReducing or Nonreducing? 1-starch 2-sucrose 3-lactose 4-glucose 5-fructose Starch Hydrolysis: Enzyme vs. Acid Catalysis Color of Iodine Test (none, some, or a lot) (no, somewhat, or completely) Is Intact Starch Still Present? Was Hydrolysis Successful? Catalyst Used KI sol'n only NONE N/A (negative control) 1-acid 2-enzyme nore→ Exp 10 Carbohydrates-page 13