Dr. Dannelly’s Bio274 Answers – Flashcards
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| Carbohydrate catabolism |
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| The breakdown of carbohydrates to release energy: three pathways Glycolysis(makes 2 ATP's) Krebs cycle(cells get most energy here) Electron transport chain(make bulk amounts of energy here)This is why we breath Some bacteria can't do Krebs cycle and electron transport chain. Fermintation only uses glycolsis When it only goes through fermintation it sacrifices energy, they don't have to work as hard to get energy because food sources are readily available(happens in the abdomin) |
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| Glycolysis |
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| The oxidation, or breakdown, of glucose to pyruvic acid produces ATP and NADH(energy bearing molecules). ATP and NADH carry a lot of energy and can be used by cell. |
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| Preparatory stage of glycolysis |
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| 2 ATP are used Glucose (6C) is split to form 2 molecules of glyceraldehde-3 phosphate(3C) It breaks the chain of 6 carbons into (2) 3 carbon molecules |
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| Dehydrogenase |
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| Uses NADH and makes NAD+ in order to continue the cycle of glycolysis |
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| Aerobic respiration |
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| The final electron acceptor is molecular oxygen(02) and the final product of central metabolism is WATER. The total energy derived from aerobic metabolism of one molecule of glucose is 38 ATPs(max efficiency) |
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| Fermentation |
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| Scientific definition: Releases energy from oxidation of organic molecules Does not require oxygen Does not use the Krebs cycle or electron transport Uses an organic molecule as the final electron acceptor. The final electron acceptor is an organic molecule and therefore the final product is an organic acid. The total energy of the fermentation of one molecule of glucose is 8 ATPs Any spoilage of food by microorganisms(general use) Any process that produces alcoholic beverages or acidic dairy products(general use) Any large-scale microbial process occurring with or without air(common definition used in industry) |
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| Energy-conserving stage of glycolysis |
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| 2 glyceraldehyde-3-phosphate are oxidized to 2 pyruvic acid 4 ATP are produced 2 NADH are produced Net of 2 ATP's are produced |
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| Alcohol fermintation |
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| Produces ethanol+CO2 |
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| Lactic acid fermintation |
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| Produces lactic acid |
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| Homolactic fermentation |
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| Produces lactic acid only |
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| Heterolactic fermentation |
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| Produces lactic acid and other compounds |
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| Durrahm tubes |
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| It is a tube upside down in a test tube. You heat it up and it drives the air out of the upside down tube. If the bacteria in the test tube ferments it produces gas and you will see the gas in the test tube, if it doesn't ferment then it will still have the colored(red or yellow) liquid in the upside down tube. |
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| Microbial growth |
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| Increase in NUMBER of cells, not size Populations Colonies Cell growth=cell replication |
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| The requirements for growth |
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| Physical requirements Temperature pH Osmotic pressure All bacteria have optimum zones that they like to grow Chemical requirements Carbon Nitrogen, sulfur, and phosphorous Trace elements Oxygen(some require, some don't) Organic growth factor |
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| What determines the minimum, optimum, and maximum growth temperature? |
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| Depends on the enzymes and proteins |
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| Mesophiles |
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| Majority of human pathogens Grow best at 37degrees C(body temperature) Ranges from 10-50 degrees C |
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| Psychrophiles |
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| optimum growing temperature is 12C Can still survive at -10C -10 to 20C is range of growth. Freezing point is 0C so these are not killed unless frozen below -10C |
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| Psychortrophs |
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| Optimum temperature is 22C(room temperature) Range from 0-30C |
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| Thermophiles |
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| Grow best at 62C Range from 40-72C |
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| Hyperthermophiles |
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| Archaea Optimum growing temperature is 95C Range from 65-110C 100C is boiling point |
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| Temperatures in this range destroy most microbes, although lower temperatures take more time. |
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| 62-140C |
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| Very slow bacteria growth range |
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| 52-62C |
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| Temperature danger zone: rapid growth of bacteria,some may produce toxins |
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| 15-52C |
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| Many bacteria survive, some may grow. Refrigerator temperatures; may allow some slow growth of spoilage bacteria, very few pathogens |
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| 0-15C |
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| Approximate temperature range at which the Bacillus cereus multiply in rice |
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| 15-43C You have to cool rice down quickly to refigerator temperatures if not, then the endospors will start to germinate and they are like toxins. You can put rice in smaller, shallower containers in order to get them it cooled down quicker. |
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| Most bacteria grow between what two pH levels? |
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| 6.5 and 7.5 |
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| Molds and yeasts grow between what two pH ranges? |
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| 5 and 6 |
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| Acidophiles |
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| Grow in acidic environments All cytoplasm is neutral even if they live in acidic environments |
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| Osmotic pressure |
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| Hypertonic environments, or an increase in salt or sugar, cause plasmolysis(water to rush out of cell and the cell shrivles up, cracks, and dies) |
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| Extreme or obligate halophiles |
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| require high osmotic pressure Can't live without the salt. Loves salty environments |
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| Facultative halophiles |
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| Tolerate high osmotic pressure Can tolerate it, but is okay without salt(prefers low salt vs. high salt) Staphylococcus aureus is a facultative halophile, it can tolerate up to 7.5% salt content |
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| Chemical requirements |
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| Carbon for building new compounds and as a source of energy Chemoheterotrophs(examples: mammals,humans,bacteria) use organic carbon sources Autotrophs(example: plants) use CO2, they don't even need sugar to live Nitrogen -In amino acids and proteins -Most bacteria decomposes proteins -Some bacteria use NH4+ or NO3- -A few bacteria use N2(in the air) in nitrogen fixation Sulfur -In amino acids, thiamine, and biotin -Most bacteria decompose proteins -Some bacteria use SO4-2 or H2S(sulfate or hydrogen sulfate) Phosphorus -In DNA, RNA, ATP, and membranes(nucleaic acids) -Phosphate is a source of phosphorus Trace elements -Inorganic elements required in small amounts -Usually as enzyme cofactors -Magnesium |
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| Thioglycollate |
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| A medium to test the oxygen needs of bacteria(metabolism) Thick liquid medium that binds oxygen It is a tube of medium that when they heat it up, it drive all of the oxygen out of the medium, they put an oxygen indicator that will turn the medium pink if it contains oxygen anywhere. As the medium cool, oxygen begins to seep back into the medium and bind with the thioglycollate, so you get a gradient from bright pink at the surface of the medium that goes to a colorless medium at the bottom of the tube because there is NO oxygen present. Because of this gradient of oxygen, you can tell which microbes prefer a lot of oxygen, a little bit of oxygen, or NO oxygen because they will grow throughout the medium wherever they can survive. Bacteria is very adaptive as far as oxygen use |
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| Toxic oxygen |
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| Singlet oxygen:1 O2- boosted to a higher-energy state Superoxide free radicals: O2*- O2*- + O2*- + 2 H+--Superoxide dismutase-->H2O2 + O2 Superoxide dismutase is an enzyme that we and bacteria have to protect us from the oxygen radicals, it makes peroxide and oxygen dimer(O2) Peroxide anion: O2 2- 2H2O2---Catalase---> 2H2O + O2 2H2O2 + 2H+---Peroxidase---> 2H2O Hydroxyl radical (OH*) Staph produces catalase, peroxide doesn't work If you eat your antioxidants it will turn the oxygen radicals(bad for your body) into oxygen dimers(good for your body) Oxygen radical disrupts your cell membranes |
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| Organic growth factors |
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| Organic compounds obtained from the environment Vitamins, amino acids, purines, and pyrimidines(nucleic acids) E.coli provides us with Vitamin K |
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| Biofilms |
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| Microbial communities Form slime or hydrogels(capsule material) Share nutrients Sheltered from harmful factors Biofilms aren't bacterial, they are produced by bacterial Bacteria attracted by chemicals via quorum sensing(sensing their own numbers) Once the bacteria sensed that they have enough bacteria present they will start to produce chemicals(takes lots of energy so they wait until enough bacteria is present so they don't waste their energy) A fish in the ocean as an "eye spot" on its tail(glucose that attracts certain microbes) once enough microbes get to the "eye spot" they will glow in the dark making it look like an eye. There preditors think that the glow in the dark eye spot is their eye, when they attack the preditor thinks it is going to swim one way but it swims the other since it thought the tail was the eye...fish doesn't get eaten. |
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| Culture media |
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| Chemically defined media: exact chemical composition is known(they weigh EVERY component out) Complex media: extracts and digests(boiled meat) of yeasts, meat, or plants -Nutrient broth -Nutrient agar |
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| Anaerobic culture methods |
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| Reducing media Contain chemicals(thioglycolate or oxyrase which is similar to thioglycolate) Heated to drive off O2 |
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| Capnophiles |
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| Microbes that require high CO2 conditions CO2 packet Candle jar--> Put petri dish in a big pickel jar with a candle lit inside. When the candle burns out it reduces the oxygen from 21-17% and the CO2 is 5% which is the perfect conditions to grow the capnophiles |
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| Respiration vs. fermentation |
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| Dehydrogenase- uses NADH and makes NAD+ in order to continue the cycle of glycolysis NAD+ + electron= NADH FADH2=electron carrier Chain=proteins Final electron acceptor in chain=oxygen, this is why we breath O2 + electron= H2O final product What's final acceptor?=oxygen What's final product?=water Electron transport+Krebs cycle=most energy Strict aerobes=can only respire Anaerobes=die in presence of oxygen |
