A nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously effect single and double stranded breaks in their target molecules. In living organisms, they are essential machinery for many aspects of DNA repair. Defects in certain nucleases can cause genetic instability or immunodeficiency.[1] Nucleases are also extensively used in molecular cloning.[2]
Depiction of the restriction enzyme (endonuclease) HindIII cleaving a double-stranded DNA molecule at a valid restriction site (5'–A|AGCTT–3').
There are two primary classifications based on the locus of activity. Exonucleases digest nucleic acids from the ends. Endonucleases act on regions in the middle of target molecules. They are further subcategorized as deoxyribonucleases and ribonucleases. The former acts on DNA, the latter on RNA.[2]
A haploid cell is one that contains one set of complete chromosomes.
Answer:
a. different alleles of the seed shape gene.
Explanation:
Mendel crossed different varieties of pea plants and he observed how phenotypic traits passed to the progeny. From these experiments, Mendel formulated the 'First Law of Segregation', where he observed that traits may exist in pairs that segregate (separate) at meiosis. During meiosis, i.e., gamete formation, these two factors separate from each other, thereby each gamete has the same probability of receiving either factor. Nowadays, we know that these two factors represent two different gene variants or 'alleles' for a given gene <em>locus</em>. Alleles can be classified into dominant or recessive as in the example above described, where the R factor (round) dominates on the r factor (wrinkled) to determine the seed shape.
The cell membrane allows substances to enter and leave the cell and gives the cell structure.
