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Genetics: Analysis and Principles Chapter 10
Chromosome organization and molecular structure
36
Biology
Undergraduate 2
09/13/2011

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Term
genome
Definition
complete set of genetic material in a particular cellular compartment
Term
virus
Definition
small infectious particle that contains nucleic acids as its genetic material, surrounded by a protein coat (capsid)
Term
nucleoid
Definition
region of bacterial cell composed of highly compacted circular chromosomes
Term
structural genes
Definition
nucleotide sequences that encode proteins
Term
intergenic regions
Definition
nontranscribed regions of dna located between adjacent genes in a bacterial chromosome
Term
origin of replication
Definition
nucleotide sequence that functions as an initiation site for the assembly of several proteins required for dna replication
Term
loop domains
Definition
a segment of chromosomal circular dna folded by dna binding proteins
Term
supercoiling
Definition
twisting forces that cause extra turns and loops in the dna structure
Term
topoisomer
Definition
chemically identical molecules that experience different levels or supercoiling conformations
Term
dna gyrase
Definition
also called topoisomerase II, generates negative supercoiling in bacterial dna
Term
topoisomerase I
Definition
bacterial enzyme that relaxes negative supercoils
Term
nucleus
Definition
membrane bound organelle in eukaryotes where chromatin is stored
Term
chromatin
Definition
highly compacted dna-protein complex found in eukaryotes
Term
centromere
Definition
section of eukaryotic chromosome that promotes formation of kinetochore
Term
telomere
Definition
specialized regions at the end of the eukaryotic chromosome, prevent "sticking"
Term
introns
Definition
non-coding intervening sequences in eukaryotic dna
Term
transposable elements (TE)
Definition
segments of dna that are capable of moving within the genome of a cell
Term
retroelement
Definition
type of TE that can be transcribed into rna, recopied into dna, and reinserted into the genome
Term
tandem array
Definition
short nucleotide sequence that is repeated many of times in a row (ex. aatataatataatataatat) often found in centromeric regions
Term
renaturation
Definition
experiment used to determine complexity of dna strand; repetitive sequences reassemble more rapidly than unique sequences as temperature drops
Term
nucleosome
Definition
double stranded segment of dna wrapped around an octomer of histone proteins
Term
histone proteins
Definition
a globular domain and a flexible charged amino terminus that are involved in compacting eukaryotic dna
Term
30 nm fiber
Definition
structure formed from the linkage of histone complexes
Term
nuclear matrix
Definition
interaction between 30nm fibers and filamentous network of proteins that further compacts the dna
Term
nuclear lamina
Definition
collection of fibers that line the inner nuclear membrane made of intermediate filaments
Term
internal nuclear matrix
Definition
part of matrix that attaches to nuclear lamina
Term
radial loop domains
Definition
eukaryotic compaction method involving the nuclear matrix and chromosomes
Term
MARs or SARs
Definition
matrix or scaffold attachment regions; sequences of chromosomal dna that bind to specific proteins in the nuclear matrix to for radial loop domains
Term
chromosome territory
Definition
location of a particular chromosome inside the nucleus
Term
heterochromatin
Definition
tightly compacted transcriptionally inactive regions of a chromosome
Term
euchromatin
Definition
less condensed areas of the chromosome that are capable of gene trascription
Term
constitutive heterochromatin
Definition
chromosomal regions that are always heterochromatic and are permanently transcriptionally inactive
Term
facultative heterochromatin
Definition
heterochromatin that can occasionally interconvert to euchromatin
Term
scaffold
Definition
nonhistone proteins of the nuclear matrix that hold the highly compacted lopps of a chromosome in place during metaphase
Term
condesin
Definition
structural maintenance of chromosome (SMC) protein that use energy from atp to affect changes in the dna structure; promotes the proper organization in the condensing of chromosomes
Term
cohesin
Definition
SMC protein that promotes the binding between sister chromatids after S phase
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