CHAPTER 10 Molecular Structure of Chromosomes and Transposable Element
30-nm Fiber Compact structure of associated nucleosome units that
is 30 nm in diameter
Alu Sequence Short stretch of DNA. Alu elements are the most
abundant transposable elements, containing over one
million copies dispersed throughout the human
genome. Alu elements were thought to be selfish or
parasitic DNA, because their sole known function is
self-reproduction. However, they are likely to play a
role in evolution and have been used as genetic markers
Autonomous Element Transposable element that contains all the information
necessary for (retro)transposition to occur
CCCTC Binding Factor (CTCF) Protein that recognizes CCCTC base sequences and
binds to the DNA and to another CTCF molecule,
thereby promoting the formation of a loop domain
Centromere Segment of a eukaryotic chromosome that provides an
attachment site for the kinetochore
Chromatin The complex of DNA and proteins that is found within
eukaryotic chromosomes
Chromosome Territory Region in the cell nucleus occupied by a chromosome;
the chromosome territories are nonoverlapping
Cohesin Multiprotein complex that facilitates the alignment of
sister chromatids
Condensin Multiprotein complex that plays a role in the
condensation of interphase chromosomes to produce
metaphase chromosomes
Constitutive Heterochromatin Regions of chromosomes that are always heterochro-
matic and are permanently transcriptionally inactive
Core Histones H2, H3, H4 histone proteins
Direct Repeats (DRs) Short DNA sequences that flank transposable element
in which the DNA sequence is repeated in the same
direction
, DNA Gyrase Enzyme that introduces negative supercoils into DNA
using energy from ATP and that can also relax positive
supercoils as they occur. AKA topoisomerase II
DNA Supercoiling Formation of additional coils in DNA due to twisting
forces
Endonuclease Enzyme that can cleave a bond between adjacent nu-
cleotides within a DNA or RNA strand
Euchromatin Less compacted regions of chromosomes, where DNA
may be transcriptionally active
E-Value With regard to results from the BLAST program, the
number of times that the match or a better one would be
expected to occur by random chance in a search of an
entire database
Exon Shuffling Phenomenon in which an exon and its flanking introns
from one gene are inserted into another gene
Facultative Heterochromatin Heterochromatin that differs among different cells of
the body
Heterochromatin During interphase, highly compacted regions of
chromosomes in which the DNA is usually
transcriptionally inactive
Highly Repetitive Sequence Base sequences that are found tens of thousands or even
millions of times throughout a genome
Histone Proteins/Histones Group of proteins involved in forming the nucleosome,
repeated structural unit within eukaryotic chromatin
Insertion Element (IS Element) Simplest TE; commonly found in bacteria
Integrase Enzyme that functions in the integration of viral DNA
or a retrotransposon into a chromosome
Intergenic Region In a chromosome, a region of DNA that lies between
two different genes
Inverted Repeats (IRs) DNA sequences found in transposable elements that are
identical (very similar) but run in opposite directions
Kinetochore Group of proteins that attach to the centromere during
meiosis and mitosis
30-nm Fiber Compact structure of associated nucleosome units that
is 30 nm in diameter
Alu Sequence Short stretch of DNA. Alu elements are the most
abundant transposable elements, containing over one
million copies dispersed throughout the human
genome. Alu elements were thought to be selfish or
parasitic DNA, because their sole known function is
self-reproduction. However, they are likely to play a
role in evolution and have been used as genetic markers
Autonomous Element Transposable element that contains all the information
necessary for (retro)transposition to occur
CCCTC Binding Factor (CTCF) Protein that recognizes CCCTC base sequences and
binds to the DNA and to another CTCF molecule,
thereby promoting the formation of a loop domain
Centromere Segment of a eukaryotic chromosome that provides an
attachment site for the kinetochore
Chromatin The complex of DNA and proteins that is found within
eukaryotic chromosomes
Chromosome Territory Region in the cell nucleus occupied by a chromosome;
the chromosome territories are nonoverlapping
Cohesin Multiprotein complex that facilitates the alignment of
sister chromatids
Condensin Multiprotein complex that plays a role in the
condensation of interphase chromosomes to produce
metaphase chromosomes
Constitutive Heterochromatin Regions of chromosomes that are always heterochro-
matic and are permanently transcriptionally inactive
Core Histones H2, H3, H4 histone proteins
Direct Repeats (DRs) Short DNA sequences that flank transposable element
in which the DNA sequence is repeated in the same
direction
, DNA Gyrase Enzyme that introduces negative supercoils into DNA
using energy from ATP and that can also relax positive
supercoils as they occur. AKA topoisomerase II
DNA Supercoiling Formation of additional coils in DNA due to twisting
forces
Endonuclease Enzyme that can cleave a bond between adjacent nu-
cleotides within a DNA or RNA strand
Euchromatin Less compacted regions of chromosomes, where DNA
may be transcriptionally active
E-Value With regard to results from the BLAST program, the
number of times that the match or a better one would be
expected to occur by random chance in a search of an
entire database
Exon Shuffling Phenomenon in which an exon and its flanking introns
from one gene are inserted into another gene
Facultative Heterochromatin Heterochromatin that differs among different cells of
the body
Heterochromatin During interphase, highly compacted regions of
chromosomes in which the DNA is usually
transcriptionally inactive
Highly Repetitive Sequence Base sequences that are found tens of thousands or even
millions of times throughout a genome
Histone Proteins/Histones Group of proteins involved in forming the nucleosome,
repeated structural unit within eukaryotic chromatin
Insertion Element (IS Element) Simplest TE; commonly found in bacteria
Integrase Enzyme that functions in the integration of viral DNA
or a retrotransposon into a chromosome
Intergenic Region In a chromosome, a region of DNA that lies between
two different genes
Inverted Repeats (IRs) DNA sequences found in transposable elements that are
identical (very similar) but run in opposite directions
Kinetochore Group of proteins that attach to the centromere during
meiosis and mitosis
