Explanation:
In the majority of cases, the extra copy of chromosome 21 comes from the mother in the egg.
In a small percentage (less than 5%) of cases, the extra copy of chromosome 21 comes from the father through the sperm.
In the remaining cases, the error occurs after fertilization, as the embryo grows.
Aspartate + a- keto acid >> Oxaloacetate + a amino acid
This reaction is occur because the a- keto acid in the equation can come from any amino acid, the 15 N from aspartate is rapidly transferred to other amino acids.
15N is symbol use as the isotope of nitrogen with mass number 15. comprises of 0.4 % of stable nitrogen found, so the relative abundance of each in amino acid is simply a reflection of how much is found in nature in general.
This isotopes is enrichment of the labelled amino acids was determined following a previously developed procedure comprising by determination of the spectral purity of the selected natural abundance amino acids.
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In the human respiratory system, gas exchange occurs across the cells of the alveoli. Alveoli or an alveolus is the deepest part of the human respiratory system. This part of the respiratory system is a place where gas exchange between oxygen and carbon dioxide occurs from inhaled air to the blood cells<span>.</span>
archaebacteria
Explanation:
The first organism on earth belonged to the archaebacteria kingdom. They were the first group of organisms that colonized the surface of the earth.
- They are of three major types methanogens, halophilic and thermoacedophilic.
- The first archaebacteria that evolved separately from bacteria and blue-green algae.
- They formed billion of year of ago.
- They lacked the characteristics of a true cell and they are known to be prokaryotes.
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Answer:
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Explanation:
