Tag Info

New answers tagged

0

Rubisco is an enzyme that is involved in the biochemical process of carbon fixation in photosynthesis, but also has an economically important error (photorespiration) which incorporates the wrong molecule (oxygen) into RuBP, therefore wasting the energy captured by the plant and producing toxic downstream products. Rubisco's error rate in carbon fixation ...


1

I would suggest following: take any one-dimensional process that is described by gaussian function. If you integrate such process along variable, you will get a sigmoidal curve. For details see normal and cumulative distribution. Now, the question is: how many biological processes are described/modeled by Gaussian distribution and dependencies? A lot! ...


1

First it is important to define what actually an error is. What you call misproduct is actually a right product for a different substrate. The enzyme has a low specificity; but you won't say hexokinase is error prone because it has wide substrate specificity. The question is — is specificity critical? Coming to the example of DNA polymerase, you should note ...


0

If Y can be seen as the inverse or absence of X function, it sounds to me like an incoherent type 3 feed-forward loop, where A activates B B activates C A inhibits/reverses C example from literature, E.coli: fnr as A, and arcA as B, cydAB as C source: http://www.pnas.org/content/100/21/11980.long


1

The gram staining relies on the differences in the bacterial membranes. The gram positive bacteria have a thick peptidoglycan layer on top of the cell membrane, the gram negative bacteria have a lipid layer on the outside followed by a thin peptidoglycan layer and then the cell membrane. See the image for clarification (from here): Crytall violet ...


0

In any coupled system the activity of one component is dependent on the other. For example translation and transcription are coupled; here translation is dependent on transcription but not vice versa. Coupling need not be bidirectional. There is no question of unfavourable thermodynamics. For coupled biochemical reactions: One of the reaction should be ...


2

The enzymes don't need physical interactions to couple reactions. Some enzymes do share subunits which are physically associated, but this is a special case. The following review gives a sort of general example during glycolysis, For example, in the biochemical pathway that breaks down glucose for energy, two enzymes work one after the other to create a ...


2

Ignoring parameters such as: Leaf shapes Difference in photosynthetic efficiency due to other metabolic factors Unequal illumination of leaves Nutrient content of the soil Photosynthesis rate of a plant1 depends on the [total number of leaves] × [surface area of a leaf]. Assuming that a tree occupies same ground area as a shrub, there will be same ...


-1

It is unneccessary for a mammal to breath in CO2, though our bodies are able to expel unneeded gasses easily. However, if there were no CO2 in the atmosphere, animals would all die, as no oxygen could be produced by plants. In other words, we don't need to breath in CO2, but we need it to be plentiful.


0

Not really a conventional source, but SCUBA divers use tanks that consist of only oxygen and nitrogen, no CO2 needed http://www.lakesidepress.com/pulmonary/books/scuba/sectionl.htm


7

The pKas of (neutral) guanine and thymine are 9-10 (ref). At high pH (>~10), those bases will be deprotonated and exist as negatively charged conjugate bases. As the deprotonated species, part of the G/C and A/T hydrogen bonding networks are eliminated. In the figure below, green dotted lines represent the hydrogen bonds that explain the observed base ...


1

No, mammals need not take in CO2 from atmosphere. The body's homeostatic function will maintain its composition by checking the amount of CO2 released out by lungs. So certainly animals would survive if put in a CO2 free atmosphere.


2

As user137 said, the general base abstracts a proton from the 2'OH and subsequently the 2'O- renders a nucleophilic attack on the δ+ Phosphorous, leading to the hydrolysis of the phosphodiester bond. There can be slight variations in the mechanism and the intermediates; for details see this review. ...


-1

Since chemical reactions are governed by quantum physics, there is a whole lot of products that can come out of mixing together several multi-atom molecules. And all of those will have non-zero probability of occurrence. But this probability is extremely low at normal temperatures, so you don't see those products. Enzymes lower activation energy and so ...


0

Chris is right here, polymerases are generating sequences, the enzymes your asking about do a single type of reaction, so you would be assessing its activity not its fidelity. A good resource I've found for looking at qc data for enzymes like these are just the product inserts from the manufacturer. NEB for example generally seems to provide sufficient qc ...


0

It is correct that imaging-based studies are super-awesome, but question seems to be about chemical. I don't know if there are antibodies available for histamine, if yes, then you can fix and label all sites of histamine. But imaging through fish tissues (say, more than 1 mm) is close to impossible with molecular resolution and sensitivity. My best guess ...


0

TMHMM is a very good standard on predicting the TMHs in the first place, so it stands to reason that predicting homologues using this approach is completely viable.


2

No it isn't necessary to breathe in CO2 from the atmosphere. For the buffer system your brain detects the amount of CO2 (H+ which is an indicator of excess or too little CO2) and adjusts your breathing automatically to compensate so that your blood's pH stays normal. No outside CO2 is needed. Your kidneys also play a similar role but the lungs are what ...


2

You should not actually homogenize samples because histamine works locally. If you know which region is releasing histamine then you can just study those regions. You can actually create a transgenic fish with GFP that is a target of histamine receptor signaling. Using mathematical models or statistical correlations you can obtain the level of histamine ...


0

Proline is replaced by Glutamic acid. Pro16 indicated a position on the protein.


3

You are looking at a protein here, which is mutated in the higher host specificity, so glucose is not involved here. What is written here are the amino acids in the three-letter-code, the notation Pro→Glu means that Proline (Pro) is replaced by Glutamic acid (Glu). The notation Pro16 means the proline on amino acid position 16 in the protein. You often find ...


20

The best ratio between weight and energy content (and of course also stability) has indeed fat. It's energy content is more than twice as high as for carbohydrates (sugars). See this table from here on the energy contents: This is the reason why animals which hibernate or migrate fed up to build up fat resources before the winter or their journey. With ...


0

Triglyceride. It has 3 fatty acids, which are non polar (water-fearing). so they are hydrophobic. These 3 fatty acids are connected to a glycerol molecule. This molecule is polar and is hydrophilic (water-loving). The glycerol is attached to the 3 fatty acids via a dehydration reaction. When they are connected, they loose a water molecule, and form an ...


4

The following answer was giving by Michael D. Dryden from http://chemistry.stackexchange.com/questions/24797/what-is-a-triglyceride/24799#24799 There is some minor argument as far as nomenclature goes for these lipids. Most sources I can find, including IUPAC have glycerides as only including esters of glycerol with fatty acids. Monoglycerides have a single ...


0

Placing the leaves in wax paper and under the pressure of several books would be beneficial (in terms of a short term preservation). This method may not be suitable for field preservation, due to the bulky nature of books and other weights, although it might be suitable if using an alternate method of pressure.


2

You may want to see: Mark W. Chase, Harold H. Hills; Taxon, Vol. 40, No. 2, 1991, pp. 215-220: 'Silica Gel: An Ideal Material for Field Preservation of Leaf Samples for DNA Studies' Summarized, the process would be the following: Place the leaves inside ziplock plastic bags; Add ten times (minium) the weight of the leaves in silica gel; After 12 hours ...


1

Lets just go with the basic Hodgkin-Huxley equation: $$C_M \frac{\text{d}V}{\text{d}t}=-g_{Na}(V-E_{Na}) -g_K(V-E_K) -g_L(V-E_L)$$ At rest ${\large\frac{\text{d}V}{\text{d}t}}=0$ and therefore $V$ is dependent on the conductances ($g_X$) of different ions. Since $g_K \sim 30\times g_{Na}$, the resting potential is closer to $E_K$ (Nernst equilibrium ...


1

Yes, there are: this is a feature of bacterial intrinsic termination. The mechanism of pausing is not as you describe, though. In bacterial transcription, two forms of termination are recognised (to my knowledge): Intrinsic termination, consisting of a hairpin and a stretch of Uridines. Rho-dependent termination, consisting of a 'loading' site for ...



Top 50 recent answers are included