Restriction endonucleases cleave at , which are sequences that read the same, 5 to 3 , on each DNA strand.

Restriction endonucleases cleave at  DNA (Deoxy ribonucleic acid) which are sequences that read the same, 5 to 3 , on each DNA strand.

Explanation:

RESTRICTION ENDONUCLEASES-: An enzyme that cleaves DNA into fragments at or near unique recognition sites within molecules known as restriction sites is a restriction enzyme, constraint endonuclease, or restrictase. One class of the larger endonuclease group of enzymes is restriction enzymes. Restriction enzymes are typically divided into five groups, which vary in structure and whether their DNA substrate is cut at their location of recognition or whether the locations of recognition and cleavage are different from one another. Both restriction enzymes make two incisions in order to cut DNA, once through each sugar-phosphate backbone (i.e. each strand) of the double helix DNA.

In bacteria and archaea, these enzymes are contained and provide a defence mechanism against invading viruses. Within a prokaryote, in a process called restriction digestion, the restriction enzymes selectively cut up foreign DNA; meanwhile, host DNA is protected by a modification enzyme (a methyltransferase) that modifies the prokaryotic DNA and blocks cleavage. Together, these two procedures form the method of restriction alteration.

gametes or germ cells are haploid cells (example: sperm and ova) containing only one set (or n) number of chromosomes and autosomal or somatic cells are diploid cells containing 2n number of chromosomes.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.