Biology  5/e   Raven/Johnson
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Synaptonemal complex: A synaptonemal complex is a homologous pair of chromosomes held together by a lattice of protein. The complex is formed in prophase I of meiosis.

Triplet reading frame: Amino acids are specified by a triplet of nucleotides. Additions or deletions to the strand of nucleotides would cause a change in the set of nucleotides that are read as a triplet.

Repression of gene transcription: Gene transcription can be blocked or "repressed" by the presence of a repressor regulator protein that blocks the movement of RNA polymerase.

Heterochromatin: Heterochromatin is DNA that remains coiled and does not code for hereditary traits.

Crossing-over: In prophase I of meiosis, homologues pair tightly and exchange portions of chromosomes. Thus, genes "cross over" to the other homologue.

Independent assortment: In mitosis and meiosis, the destination pole is determined randomly. Thus, genes located on different chromosomes from each other are assorted randomly and independently.

Cell cycle "check points": At several "check points" in the cell cycle, further progress depends upon successful tests that measure the condition of the cell. This regulation is carried out by a variety of cyclins and cyclin-dependent protein kinases.

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