Tessa A. Morris Week 2: Difference between revisions

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:::1. Less than or equal 44 mM the values for C{{nowrap|1=O<sub>2</sub>}} production and {{nowrap|1=O<sub>2</sub>}} consumption differed, but no no changes in the residual glucose concentration were observed
:::1. Less than or equal 44 mM the values for C{{nowrap|1=O<sub>2</sub>}} production and {{nowrap|1=O<sub>2</sub>}} consumption differed, but no no changes in the residual glucose concentration were observed
::E. Data showed that except at 29 mM ammonia in the feed, no significant changes in the carbon metabolism occurred when the ammonia concentration in the feed was increased and the culture was switched from ammonia limitation to ammonia excess
::E. Data showed that except at 29 mM ammonia in the feed, no significant changes in the carbon metabolism occurred when the ammonia concentration in the feed was increased and the culture was switched from ammonia limitation to ammonia excess
:V. Chemical Process
::A. Intracellular ammonia reacts with α-ketoglutarate to produce glutamate
::B. Glutamate is converted into glutamine by incorporation of another ammonium ion
:VI. Effect of increasing ammonia concentrations on the intracellular α-ketoglutarate, glutamate, and glutamine concentrations
::A. α-ketoglutarate concentration decreased from 10 to about 5 mmol {{nowrap|1=g<sup>-1</sup>}} when the culture conditions
changed from ammonia limitation to ammonia excess
::B. Intracellular glutamate concentration increased from ~75 to 220 mmol {{nowrap|1=g<sup>-1</sup>}}
::C. Intracellular glutamine concentration increased linearly from about 4 mmol {{nowrap|1=g<sup>-1</sup>}} at 29 mM ammonia to about 27 mmol {{nowrap|1=g<sup>-1</sup>}} at 118 mM ammonia
::D. With constant ammonia flux but increasing ammonia concentrations, the intracellular concentrations of glutamate and glutamine increase

Revision as of 22:21, 25 January 2015

Biomathematical Modeling Navigation

User Page: Tessa A. Morris
Course Page: Biomathematical Modeling

Assignment

Week 2 Assignment

Ten Biological Terms

  1. Flux: (Science: radiobiology) The total amount of a quantity passing through a given surface per unit time. Typical quantities include (magnetic) field lines, particles, heat, energy, mass of fluid, etc. Common usage in plasma physics is for flux by itself to mean magnetic field flux, unless specified otherwise. Source
  2. Northern Blot Analysis: A procedure... used mostly to separate and identify rNA fragments; typically via transferring RNA fragments from an agarose gel to a nitrocellulose filter followed by detection with a suitable probe. Source
  3. Biosynthesis: The production of a complex chemical compound from simpler precursors in a living organism, usually involving enzymes (to catalyze the reaction) and energy source (such as ATP) Source
  4. Assimilation The conversion of nutriment into a useable form (e.g. liquid or solid) that is incorporated into the tissues and organs following the processes of digestion; The chemical alteration of substances in the bloodstream by the liver or cellular secretions. Source
  5. Dehydrogenase:enzyme that oxidizes a substrate by transferring hydrogen to an acceptor that is either NAD/NADP or a flavin enzyme. An enzyme that is used to remove hydrogen from its substrate, which is used in the cytochrome (hydrogen carrier) system in respiration to produce a net gain of ATP. Source
  6. Permease: general term for a membrane protein that increases the permeability of the plasma membrane to a particular molecule, by a process not requiring metabolic energy. A type of protein believed to be involved in active transport and acts as a protein carrier. Source
  7. Metabolite: a chemical compound that is produced or consumed during metabolism. Source
  8. Metabolism: the sum of all the physical and chemical processes by which living cells produce and maintain themselves. Source
  9. Synthetase: catalyse synthesis of molecules, their activity being coupled to the breakdown of a nucleotide triphosphate. Source
  10. Transferases: enzymes that catalyze the transfer of functional groups between donor and acceptor molecules. Source

Outline

I. Overview
A. The purpose was to investigate if the governing factor of nitrogen metabolism may be the concentration of ammonia rather than its flux
B. Saccharomyce cerevisiae was the model organism
C. The effect of the input of ammonia concentrations ranged from nitrogen limitation to nitrogen excess and glucose limitation
II. Introduction
A. Ammonia is a preferred nitrogen source for Saccharomyces cerevisiae
B. The components of nitrogen metabolism are regulated at both the level of gene expression and the level of enzyme activity
C. There is evidence saying that ammonia concentration itself plays a part in nitrogen metabolism
1. Cultures differ in the external ammonia concentration and in the rate of ammonia assimilation
2. Because of the varying parameters it is possible that the flux, rather than the concentration is the governing parameter
III. Physiological parameters
A. S. cerevisae SU32 was grown in continuous cultures with feeds containing the following ammonia concentrations: 29, 44, 61, 66, 78, 90, 96, 114, and 118 mM
B. The glucose concentration was fixed at 100 mM
C. The dilution rate was held constant at 0.15 h-1
IV. Data
A. Increasing the ammonia concentration from 29 to 61 mM
1. Biomass increased from 4.9 to 8.2 g liter-1
2. The residual ammonia concentration in the culture medium was constant at about 0.022 mM
3. Ammonia was limiting
B. When the ammonia concentration was above 61 mM
1. Biomass remained at about 8.2 g
2. The residual ammonia concentration in the culture medium increased linearly up to 62 mM
3. Glucose became limiting
C. The ammonia flux was calculated by taking the difference between the input ammonia concentration and the residual ammonia concentration, dividing by the biomass, and then multiplying by the dilution rate
1. Over the entire range of ammonia concentrations, the ammonia flux into biomass was about 1.1. mmol g-1 h-1
D. At an input ammonia concentration above 44 mM, the CO2 production and O2 consumption, thus the respiratory quotient (CO2 produced divided by O2 consumed), remained relatively constant
1. Less than or equal 44 mM the values for CO2 production and O2 consumption differed, but no no changes in the residual glucose concentration were observed
E. Data showed that except at 29 mM ammonia in the feed, no significant changes in the carbon metabolism occurred when the ammonia concentration in the feed was increased and the culture was switched from ammonia limitation to ammonia excess
V. Chemical Process
A. Intracellular ammonia reacts with α-ketoglutarate to produce glutamate
B. Glutamate is converted into glutamine by incorporation of another ammonium ion
VI. Effect of increasing ammonia concentrations on the intracellular α-ketoglutarate, glutamate, and glutamine concentrations
A. α-ketoglutarate concentration decreased from 10 to about 5 mmol g-1 when the culture conditions

changed from ammonia limitation to ammonia excess

B. Intracellular glutamate concentration increased from ~75 to 220 mmol g-1
C. Intracellular glutamine concentration increased linearly from about 4 mmol g-1 at 29 mM ammonia to about 27 mmol g-1 at 118 mM ammonia
D. With constant ammonia flux but increasing ammonia concentrations, the intracellular concentrations of glutamate and glutamine increase
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