Answer:
The presence of an additional chromosome
Explanation:
Look at "pair" 21. See how there are THREE chromosomes instead of TWO? Normally, there would only be two chromosomes in each pair but this karyotype shows a trisomy (see def. below) of the 21st pair. This was caused by a nondisjunction mutation of the 21st pair. The is also the karyotype of a person with Down's Syndrome.
Definition of Trisomy:
A condition of the presence of three chromosomes in a pair instead of two. This normally causes developmental irregularity.
Bacteria produce restriction endonucleases, or restriction enzymes, that recognize and cut up foreign DNA, including certain phage DNA.
An acid has <em><u>c. more </u></em> hydrogen ions than a base.
The tissue in which all cells contact the basement membrane, even though some appear (at first glance) to be stacked on top of others, is called pseudostratified <span>columnar epithelium.
</span> The pseudostratified columnar epithelium has epithelial cells whose nucleis are at different levels.
<span>The upper respiratory tract epithelium is example of this type of epithelium.</span>
