AhmadWeek3: Difference between revisions
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==Word Definitions== | ==Word Definitions== | ||
#[http://www. | #[http://www.biology-online.org/dictionary/Flux Flux]: "The total amount of a quantity passing through a given surface per unit time." | ||
#[http://www. | #[http://www.biology-online.org/dictionary/Permease 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." | ||
#[http://www.biology-online.org/dictionary/Oligonucleotide Oligonucleotide]: "Linear sequence of up to 20 nucleotides joined by phosphodiester bonds." | |||
#[http://www.biology-online.org/dictionary/Gram-negative Gram-negative]:"This is a primary characteristic of bacteria that have a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide containing endotoxin." | |||
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Revision as of 00:43, 31 January 2013
Part 1: Experimenting with different levels of ammonia
- Saccharomyces cerevisae, a type of yeast, uses ammonia as its primary nitrogen source
- Past research has shown that ammonia concentration affects growth
- In this paper, the researches wanted to know if ammonia flux, and not concentration, is the limiting factor
- Physiological Parameters
- S. cerevisae was first grown in cultures with different levels of ammonia, but fixed glucose concentrations
- Increases in the ammonia concentration from 29 to 61 mM showed a change in biomass from 4.9 to 8.2 g/L
- After 61 mM, however, there was no significant increase in biomass
- Formula to calculate ammonia flux: [dilution x (input ammonia concentration - residual ammonia concentration)/biomass]
- At a level above 44 mM, oxygen consumption was equal to carbon dioxide production
- Ketoglutarate, Glutamate, Glutamine concentrations as ammonia concentrations were increased
- Ketoglutarate: Decreased
- Glutamate: Increased
- Glutamine: Increased
- Figure 1
- X axis: NH4 concentration
- Y axis:
- A: Residual NH4 concentration
- B: 02 consumption/CO2 production
- C: Ketoglutarate, Glutamate, Glutamine concentrations
Part 2: Gene Expression
- Northern Analyses are RNA analyses that were done to see how the changes in nitrogen affect nitrogen-regulated genes
- Figure 2 shows gene expression in response to different levels of NH4 concentrations
- X axis: NH4 concentration
- Y axis: Gene expression
- Permease-encoding genes:
- GAP1
- PUT4
- Biosynthetic genes
- ILV5
- HIS4
- GDH1
- GLN1
Part 3: Enzymes
- Figure 3 shows enzyme activity at different NH4 concentrations
- X axis: NH4 concentration
- Y axis: Enzyme activity
- Enzymes Studied:
- NADPH
- NAD-DGH
- GS Transferase
- NADPH activity consistently decreased with increased NH4
- NAD-GDH activity consistently increased with increased NH4
- GS Transferase and Synthetase decreased slightly until 60 mM, but then leveled off with increased NH4
- The conclusion of the paper is that that the nitrogen metabolism of S. cerevisiae is regulated by ammonia concentration
- The species may have an ammonia sensor
Word Definitions
- Flux: "The total amount of a quantity passing through a given surface per unit time."
- 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."
- Oligonucleotide: "Linear sequence of up to 20 nucleotides joined by phosphodiester bonds."
- Gram-negative:"This is a primary characteristic of bacteria that have a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide containing endotoxin."