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Chapter 5&6
Chapter 5&6
81
Microbiology
Undergraduate 1
10/03/2012

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Term
Binary Fission
Definition
An asexual process in bacterial and archaeal cells by which a cell divides to form two new cells while maintaining genetic constancy
Term
Generation Time
Definition
The time interval for a cell population to double in number
Term
Incubation Period
Definition
The time that elapses between the entry of a pathogen into the hose and the appearance of signs and symptoms
Term
What are the phases of a population growth curve?
Definition
Lag Phase- no cell divisions occur Log Phase- active stage of growth-primary metabolites are being synthesized Stationary Phase- reproductive and death rates equalize and plateau- environmental resistance is factors that limit population growth/secondary metabolites are produced these are chemicals not necessary for growth Decline Phase- nutrients become low and cells start dying off
Term
Vegetative Cell
Definition
Cells that actively metabolize and obtain nutrients
Term
Endospore
Definition
A dormant structure that persist during periods of unfavorable conditions
Term
Dipocolinic Acid
Definition
A chemical found in endospores that stabilizes its proteins and DNA
Term
Sporulation
Definition
Bacterial chromosome is replicated, One chromosome condenses, Asymmetric cell division partitions prespore from mother cell, Transverse septum forms and prespore is engulfed by mother cell, Cortex develops around the prespore followed by a piece of spore coat, Spore wall is complete; vegetative cell disintegrates, Free spore is released
Term
Psychrophile
Definition
A microbe that grows in cold temperatures
Term
Mesophile
Definition
A microbe that grows in moderate temperatures
Term
Thermophile
Definition
A microbe that grows in hot temperatures
Term
Obligate Aerobe
Definition
Requires O2 (Oxygen)
Term
Obligate Anaerobe
Definition
Cannot grow in the presence of O2 (Oxygen)
Term
Facultative
Definition
Can grow in the presence or absence of O2 (Oxygen)
Term
Microaerophile
Definition
Requires low concentrations of O2 (Oxygen)
Term
Capnophile
Definition
CO2 (Carbon Dioxide) loving organisms
Term
Aerotolerant
Definition
Anaerobe that can tolerate O2 (Oxygen) however does not derive any benefit from it
Term
Halophile
Definition
Lives in environments rich in salt
Term
Hypotonic
Definition
Solute concentration is lower than the cell. Water enters by osmosis. Cell becomes bigger
Term
Isotonic
Definition
Solute concentration is equal to that of the cell. Water is neither gained nor lost.
Term
Hypertonic
Definition
Solute concentration is higher than the cell. Water leaves by osmosis and the cell becomes smaller.
Term
Synthetic Medium
Definition
Chemically defined; contain highly purified organic and inorganic compounds.
Term
Non-Synthetic Medium
Definition
Also known as complex media contains at least one ingredient that is not chemically defined such as blood, serum, meat extract etc..
Term
Carbon
Definition
Serves as the backbone of organic molecules
Term
Carbon Cycle
Definition
Carbon enters the ecosystem by photosynthesis or chemoautotrophy and leaves by cellular respiration
Term
Nitrogen
Definition
Used for synthesizing proteins, DNA, RNA, and ATP
Term
Nitrogen Cycle
Definition
Nitrogen enters the ecosystem by nitrogen fixation and leaves by denitrification
Term
Oxygen
Definition
Major constituent of organic molecules, Required for aerobic cellular respiration
Term
Hydrogen
Definition
Major constituent of organic molecules, Involved in maintaining pH, Important for hydrogen bonding in macromolecules, Prime force in oxidation-reduction reactions of cellular respiration
Term
Phosphorus
Definition
Constituent of DNA, RNA, nucleotides, ATP, phospholipids, and coenzymes, PO43- is the primary inorganic source of the element
Term
Sulfur
Definition
Constituent of proteins, Cysteine and methionine are amino acids that contain sulfur
Term
Microelements
Definition
Compounds or substances needed in small amounts for proper functioning in the body.
Term
Growth Factors
Definition
Substances that cannot be synthesized and must be obtained as a nutrient such as temperature, oxygen, ph, hydrostatic and osmotic pressure
Term
Fastidious Organism
Definition
Require special growth factors
Term
What are two major solidifying agents for media?
Definition
Agar and gelatin
Term
Which solidifying agent has the most disadvantages?
Definition
Gelatin, it will not stay solid like agar it will melt
Term
Synthetic Media
Definition
Chemically defined; contains highly purified organic and inorganic compounds
Term
Non-synthetic Media/Complex Media
Definition
Contains at least one ingredient that is not chemically defined such as blood, serum, meat extract, infusions, milk, yeast extract, malt extract, soybean digests, and peptone
Term
General Purpose Medium
Definition
Designed to grow a broad spectrum of microorganisms such as TS broth, TSA, nutrient broth, and nutrient agar
Term
Enriched Medium
Definition
Enriched with blood, serum, hemoglobin, or special growth factors, Promotes the growth of fastidious organisms, Chocolate agar is an example
Term
Selective Medium
Definition
Contains a chemical that inhibits the growth of certain organisms, but promotes the growth of others, Lowenstein-jensen medium contains malachite green; this medium promotes the growth of mycobacterium while inhibiting other bacteria
Term
Differential Medium
Definition
Can grow several types of microorganisms, but can distinguish among them due to different appearances on the medium such as color of the colonies or color of the medium where the microorganisms are growing, Different types of gram-negative intestinal bacteria can be identified on chromacult agar due to the imparting of color to the colonies
Term
Fermentation Medium
Definition
Determines whether a microorganism can ferment a particular carbohydrate, Fermentation is an anaerobic process that often generates acids, If the carb is fermented acid is produced and can be detected by a ph indicator dye, Phenol red fermentation tubes turn yellow if the organism can ferment the sugar if it can’t it stays red
Term
How can we isolate microorganisms in a mixed culture?
Definition
By using the pour-plate method where the mixed culture is incubated on molten agar and after 24-48 hours the cells divide and form discrete colonies, or the streak-plate method where a series of streaks is made on the surface of nutrient agar of one area of the plate and dragged through all four sides after incubation each cell will grow to form a discrete colony on the plate
Term
Turbidity
Definition
Medium becomes cloudy as the number of microorganisms increase, this is measured with a spectrophotomer
Term
Direct Count
Definition
Involves counting the number of cells in a sample microscopically this is done with a cytometer
Term
Viable Plate Count
Definition
Determines the colony forming units of serially diluted samples using pour plate technique or spread plate technique
Term
Most Probable Number
Definition
A statistical estimation of the number of microorganisms by counting the number of tubes that demonstrate either turbidity or gas production
Term
Filtration
Definition
A known volume of liquid or air is passed through a filter that traps the microorganisms, A filter is placed on an agar medium and incubated the colonies are counted after the incubation period
Term
What is are the differences between anabolism and catabolism?
Definition
Anabolism is reactions that build up- buildup of small molecules, products are large molecules, mediated by enzymes, energy-requiring, Catabolism is reactions that break down- breakdown large molecules, products are small molecules, mediated by enzymes, energy releasing
Term
What is a catalyst?
Definition
A catalyst is a chemical agent that changes the rate of a reaction without being consumed in the reaction
Term
What are the characteristics of enzymes?
Definition
Enzymes are proteins that catalyze biochemical reactions, Enzymes are not consumed or permanently altered by the reaction, Enzymes are reusable, Enzymes exhibit specificity for their particular substrate, Enzymes are effective in low concentrations, Enzymes lower the energy of activation of a biochemical reaction, The names of enzymes typically end in the suffix -ase
Term
Why are cofactors important for conjugated enzymes?
Definition
Cofactors are organic or inorganic molecules that are required for the activity of a certain conjugated enzymes
Term
Why is the active site important for enzyme function?
Definition
An active site is the part of an enzyme that directly binds to a substrate and carries a reaction. It contains catalytic groups which are amino acids that promote formation and degradation of bonds. By forming and breaking these bonds, enzyme and substrate interaction promotes the formation of the transition state structure. Enzymes help a reaction by stabilizing the transition state intermediate. This is accomplished by lowering the energy barrier or activation energy- the energy that is required to promote the formation of transition state intermediate
Term
What is an allosteric site? Why are they important for the regulation of metabolic pathways?
Definition
An allosteric enzyme has a regulatory site as well as an active site. An inhibitory substance binds to the regulatory site and changes the shape of the enzyme distorting the active site. This prevents the substrate from binding to the active site inhibiting the enzymatic reaction.
Term
Distinguish between competitive and non-competitive inhibitors.
Definition
Competitive inhibitor is an inhibitor that binds to the avtive site it competes with the substrate for the active site but no product is made, Non-competitive inhibitor is an inhibitor that binds to another site where binding is irreversible
Term
How do sulfa drugs work?
Definition
Sulfa drugs act as competitive inhibitors of a bacterial enzyme. Bacteria need PABA in order to make metabolites leading to the making of folic acid which is necessary for DNA replication. Sulfa drugs out compete PABA. Since no product is made, no folic acid is made. The bacteria stop dividing because they are unable to perform DNA replication.
Term
What factors can denature an enzyme?
Definition
Denaturization occurs when there is an extreme change that causes the enzyme to become unstable and change its shape. The factors that can cause denaturization are temperature, pH, and osmotic pressure
Term
Distinguish between exergonic and endergonic reactions
Definition
Exergonic reaction is an energy releasing reaction- downhill to release energy to make ATP- catabolic, Endergonic reaction is an energy requiring reaction- uphill reaction- ATP needed for energy- anabolic
Term
What are oxidation-reduction reactions?
Definition
How cells transfer energy from one compound to another- always occurs in pairs- if one is oxidized a second is reduced- To remember oxidation and reduction; LEO the chemistry lion says GER! LEO: lose electrons oxidation, GER: gain electrons reduction
Term
Explain the ATP cycle
Definition
ATP is made by the phosphorylation of ADP: energy released from the oxidation of nutrient molecules provides the energy to make ATP
Term
What is the role of coenzymes in cellular respiration?
Definition
Coenzymes carries energy from the broken chemical bond of the substrate to the formation of the high energy bond of ATP Coenzymes act as mobile electron carriers, Coenzymes transport electrons to the electron transport chain where most of the ATP is made Most important coenzyme is NAD+
Term
Summarize glycolysis
Definition
Is a sugar splitting reaction that occurs in the cytosol of eukaryotic cell
Term
Summarize the bridging step
Definition
Step between glycolysis and citric acid cycle, Occurs in cytosol of eukaryotic cells, occurs twice for each molecule of glucose, pyruvic acid is converted into acetyl CoA, carbon dioxide is generated
Term
Summarize the citric acid cycle
Definition
Occurs twice for each molecule of glucose, occurs in the matrix of the mitochondrion or the eukaryotic cell and cytosol of the prokaryotic cell, carbon dioxide is generated, GTP is converted in ATP, the NADH and the FADH2 go to the electron transport chain
Term
Summarize the electron transport chain
Definition
A series of electron carriers bound to a membrane, occurs on the cristae of the mitochondrion of the eukaryotic cell and the mesosome of the prokaryotic cell, coenzymes drop off their electrons in the ETC, electrons are passed along a series of 9 carriers, oxygen is the terminal electron acceptor and is converted into water, as electrons are passed along the electron acceptors, energy is released to produce ATP
Term
How many ATP molecules are made aerobically?
Definition
38 ATPs for Prokaryotic 36 ATPs for Eukaryotic
Term
Summarize how ATP is made by chemiosmosis
Definition
Energy released in the electron transport chain is used to pump hydrogen across the membrane from the matrix into the intermembrane space.
Term
What is anaerobic respiration? How many ATP molecules are made?
Definition
Anaerobic respiration Is an energy releasing process that does not require oxygen, Anaerobic respiration is fermentation, only 2 ATPs are made
Term
What is the function of fermentation?
Definition
Fermentation pathway recycles coenzymes for ongoing glycolysis
Term
Alcohol Fermentation
Definition
Performed by fermentative yeasts, alcohol and carbon dioxide are produced
Term
Homolactic Fermentation
Definition
Produces lactic acid, performed by many bacteria, performed by our muscle tissue when oxygen levels fall
Term
Heterolactic Fermentation
Definition
Occurs in many bacteria, produces a comination of acids, also H2 and CO2
Term
What is the methyl red test?
Definition
Tests for acid products
Term
What is the Voges-Proskauer test?
Definition
Tests for neutral products
Term
What is the difference between light-dependent and light-independent reaction?
Definition
Light dependent needs light to react; light independent does not need light to react
Term
Photoautotroph
Definition
Needs co2 and light
Term
Chemoautotroph
Definition
Needs co2 and inorganic chemicals
Term
Photoheterotroph
Definition
Need organic molecules and light
Term
Chemoheterotroph
Definition
Need organic molecules and organic chemicals
Term
What is the difference between a saprobe and a parasite?
Definition
Saprobes feed on dead organic matter Parasites feed on living organic matter
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