chapter 8

  • Transformation: The process of transferring genetic information between cells by DNA molecules.

  • Transforming factor: The molecular agent of transformation; DNA.

  • Covalent bonds: Chemical bonds that result from electron sharing between atoms. Covalent bonds are formed and broken during chemical reactions.

  • Hydrogen bond: A weak chemical bonding force between hydrogen and another atom.

  • Deoxyribonucleic acid (DNA): A molecule consisting of antiparallel strands of polynucleotides that is the primary carrier of genetic information.

  • Ribonucleic acid (RNA): A nucleic acid molecule that contains the pyrimidine uracil and the sugar ribose. The several forms of RNA function in gene expression.

  • Nucleotide: The basic building block of DNA and RNA. Each nucleotide consists of a base, a phosphate, and a sugar.

  • Nitrogen-containing base: A purine or pyrimidine that is a component of nucleotides.

  • Purine: A class of double-ringed organic bases found in nucleic acids.

  • Pyrimidine: A class of single-ringed organic bases found in nucleic acids.

  • Adenine and guanine: Nitrogen-containing purine bases found in nucleic acids.

  • Thymine, uracil, and cytosine: Nitrogen-containing pyrimidine bases found in nucleic acids.

  • Sugar: In nucleic acids, either ribose, found in RNA, or deoxyribose, found in DNA. The difference between the two sugars is an OH group present in ribose and absent in deoxyribose.

  • Phosphate group: A compound containing phosphorus chemically bonded to four oxygen molecules.

  • Ribose and deoxyribose: Pentose sugars found in nucleic acids. Deoxyribose is found in DNA, ribose in RNA.

  • Semiconservative replication: A model of DNA replication that provides each daughter molecule with one old strand and one newly synthesized strand. DNA replicates in this fashion.

  • DNA polymerase: An enzyme that catalyzes the synthesis of DNA using a template DNA strand and nucleotides.

  • Chromatin: The DNA and protein components of chromosomes, visible as clumps or threads in nuclei.

  • Histones: DNA-binding proteins that help compact and fold DNA into chromosomes.

  • Nucleosome: A bead-like structure composed of histones wrapped with DNA.

  • Centromere: A regions of a chromosome to which spindle fibers attach during cell division. The location of a centromere gives a chromosome its characteristic shape.

  • Telomere: Short repeated DNA sequences located at each end of chromosomes.

  • Telomerase: An enzyme that adds telomere repeats to the ends of chromosomes, keeping them the same length after each cell division.