Chapter 13.txt

One of four nitrogen-containing bases in nucleotide monomers of DNA or RNA; also refers to a nucleotide having an adenine base component.

One of a class of viruses that infects bacteria.

A genetically identical copy of DNA, a cell, or a multicelled organism.

One of the four nitrogen-containing bases in nucleotide monomers of DNA or RNA; also applies to a nucleotide that contains a cysteine base.

Deoxyribonucleic acid. Double-stranded nucleic acid twisted into a helical shape; its base sequence encodes the primary hereditary information for all living organisms and many viruses.

Type of enzyme that catalyzes the sealing of short stretches of DNA into a continuous strand during replication; also seals strand breaks.

Type of enzyme that catalyzes the addition of free nucleotides to new DNA strands during replication; also proofreads and corrects mismatches.

Any enzyme-mediated process that fixes DNA replication errors or strand breaks.

Process by which a cell duplicates its DNA molecules before it divides into daughter cells.

One of four nitrogen-containing bases in nucleotide monomers of DNA or RNA; also may refer to a nucleotide that contains a guanine base.

Type of enzyme that catalyzes breaking of hydrogen bonds during DNA replication so the two strands of double helix can unwind from each other.

Small organic compound with a five-carbon sugar, a nitrogen-containing base, and a phosphate group. Functions as coenzymes or monomers of nucleic acids.

A nucleotide base with a double ring structure; e.g., adenine or guanine.

A nucleotide base with a single ring structure; e.g., cytosine, thymine, uracil.

Type of enzymes that repairs nucleotide mismatches in a DNA strand.

[Gk. semi�, half, + L. conservare, to keep] Mechanism by which a DNA molecule is duplicated. The double helix unzips along its length, exposed bases of each strand are a template upon which a new strand is assembled, then each conserved strand and its new partner wind up in a double helix. Two double helixes, each with a parental strand and new strand of DNA, result.

Self-perpetuating, undifferentiated animal cell. A portion of its daughter cells becomes specialized; e.g., red blood cells from stem cells in bone marrow.

A cap of repetitive DNA sequence on the end of a chromosome. Each nuclear division, enzymes digest a bit of it; cells stop dividing when only a nubbin remains.

One of four nitrogencontaining bases in nucleotide monomers of DNA; also applies to a nucleotide with a thymine base component.

Film image of xrays scattered by a crystalline sample; the resulting pattern of streaks and dots can be used to calculate the spacing between the atoms in the crystal lattice.