Answer:
The correct answer is e. <em>Postzygotic barrier.</em>
Explanation:
Different species can not mate and produce viable, healthy and fertile descendence, due to certain mechanisms of <u>reproductive isolation</u>.
These mechanisms involve different kinds of barriers that make it difficult for two different species to produce viable and fertile progeny.
One of these is the <u>postzygotic barrier</u>, which avoids the hybrid zygote to develope to adultness. In these situations, there is a mix of chromosomes that can not happen to meet or that they lack information.
There are cases in which the embryo dies, but some times the individual can reach some more advanced develope stages. If this is the case, in general, they can not survive because the organism is unhealthy. And if they reach adultness in good sate they can not leave descendence, as they are sterile.
The answer is aquifer because an aquifer is a body of permeable rock which can obtain or transmit groundwater (it’s underground and not on the surface).
Lactate dehydrogenase is an enzyme that can:
• catalyzes the conversion of lactate to pyruvate and back, and
• converts NAD+ to NADH and back.
The reaction of lactate dehydrogenase usually occurs during a tissue damage. So, pyruvate, (the final product of glycolysis), is converted to lactate when oxygen is absent (in low concentration).
When the concentrations of lactate increases (as the product of lactate dehydrogenase reaction), the enzyme exhibits feedback inhibition (negative feedback).
Answer:
The correct answer is - a) Lys b) AAG
Explanation:
As mention in question that whatever mutation took place was single nucleotide substitution which changes the complete amino acid here what one can do is he can analyze all 64 codons which code for different amino acids to find out.
Revertant 3 which had methionine in the 64 codons one codon codes for methionine which is AUG so we will search for most similar and found that-
Threonine = ACG
Glutamate = GAG
Arginine = AGG
Methionine = AUG
Lysine = AAG
In the mutant protein most possible amino acid present could be lysine as lysine coded by AAG in E.coli and if we do point mutation in the codon of lysine we can get all other four codon for given revertants :
AAG= lysine if second nucleotide converted to C so it will become ACG and will code for threonine as in Revertant 1.
AAG= lysine if first nucleotide converted to G - become GAG and will code for Glutamate as in Revertant 2.
AAG =lysine if second nucleotide converted to U - AUG and will code for methionine as in Revertant 3.
AAG= lysine if second nucleotide converted to G - AGG and will code for arginine as in Revertant 4.
So, lysine codon AAG is the only position in the genetic code that can, in one step, mutate to either Thr, Glu, Met, or Arg.
Thus, the correct answer is - a) Lys b) AAG