10. Molecular Structure of Chromosomes and Transposable Elements Flashcards
the structures within living cells that contain the genetic material.
Chromosome
all of the chromosomes and DNA sequences that an organism or species can possess.
Genome
a short segment of DNA that can be inserted in multiple locations within chromosomal DNA.
Transposable Element (TE)
genes that produce mRNA and encode polypeptides
Protein-Coding (Structural) Genes
in a chromosome, a region of DNA that lies between two adjacent genes.
Intergenic Region
a site on a chromosome that functions as an initiation site for the assembly of several proteins that begin the process of DNA replication.
Origin of Replication
short DNA sequences that occur many times within a species’ genome.
Repetitive Sequences
a darkly staining region that contains the genetic material of mitochondria, chloroplasts, or bacteria.
Nucleoid
a loop of DNA that is found in a bacterial chromosome and is typically 10 kbp in length.
Microdomain
a set of DNA-binding proteins found in bacteria that facilitate chromosome compaction and organization.
Nucleoid-Associated Proteins (NAPs)
the formation of additional coils in DNA due to twisting forces.
DNA Supercoiling
DNA conformations that differ with regard to supercoiling.
Topoisomers
an enzyme that introduces negative supercoils into DNA using energy from ATP and that can also relax positive supercoils when they occur.
DNA Gyrase (Topoisomerase II)
an enzyme that alters the degree of supercoiling in DNA; it relaxes negative supercoils.
Topoisomerase I
Noncoding Intervening sequences
Introns
a region of an RNA molecule that remains after splicing has removed the introns. In mRNA, the coding sequence of a polypeptide is contained within it.
Exons
a segment of a eukaryotic chromosome that provides an attachment site for the kinetochore.
Centromere
a group of proteins that attach to the centromere during meiosis and mitosis.
Kinetochore
specialized repeated sequences found at the ends of eukaryotic chromosomes.
Telomeres
the number of times a particular base sequence appears throughout the genome of a given species.
Sequence Complexity
base sequences that are found a few hundred to several thousand times in a genome.
Moderately Repetitive Sequence
base sequences that are found tens of thousands or even millions of times throughout a genome.
Highly Repetitive Sequences
a region in DNA in which a very short nucleotide sequence is repeated many times in a row.
Tandem Array (Repeat)
a process in which a short segment of DNA called a transposable element is inserted into a new location in the genome.
Transposition
a site in a chromosome that tends to break at a fairly high rate due to the presence of a transposable element.
Mutable Site (Locus)