Science Fill in the blank

The nucleotides in a helix are joined together by ______ bonds.

The constriction of the chromosome at any point is called ______.

The end of the chromosome is called ______.

_____ mutation is the changes occurring in the nucleotide sequence of a gene.

______ is the enzyme, which separates the double helix of DNA, above the replication fork.

The chromatids are held together by ______.

The branch of biology that deals with the genes, genetic variation and heredity of living organisms is called ______.