genetics chapter 12
Bacterial chromosomes structures are...
Circular, double-stranded DNA compacted into nucleoid
chromatin remodeling- to accommodate ________-_____________ interactions, ________________ structure must change
DNA-protein, chromatin
Topoisomerases
Enzymes that cut one or both DNA strands
bacterial chromosomes DNA is associated with..
HU and H-NS DNA-binding proteins (Histone-like Nucleoid Structuring Protein)
Viral Chromosome Structures are...
Nucleic acid, either DNA or RNA, single or double stranded
heterochromatin replicates later in ___ _____________ than euchromatin
S phase
viral and bacterial chromosomes are...
Single nucleic acid molecule
acetylation is the addition of _________ group to ____________ charged amino group on side chain (lysine) changes net charge of protein by _____________ positive charge
acetyl, positively, neutralizing
some chemical modifications include...
acetylation, methylation, phosphorylation
acetylation enzyme is histone ____________________
acetyltransferase (HAT)
euchromatin is uncoiled and _________?
active
chromosome banding
allows cytogeneticists to identify each chromosome in a karyotype
methylation adds methyl group to ____________ and __________ residues in histones
argine and lysine
viral and bacterial chromosomes are largely devoid of...
associated proteins
Nucleosomes resemble?
beads on a string
Puff regions are...
bulges where DNA has uncoiled that are visible manifestations of high level gene activity (transcription that produces RNA)
___________ _____________ are important to genetic function
chemical modifications
what do chromatins do during cell division?
chromatin coils and condenses back into visible chromosomes
heterochromatin telomere maintains...?
chromosome integrity
Viral Chromosome Structures are ____________ or ___________ molecules
circular or linear
supercoiled dna is more _______ and ____________ than linear forms
compact, sediment more rapidly
nucleosomes are ___________ several times to form __________ _________________
condensed, intact chromatids
heterochromatin is __________ and __________ together
dna, proteins
histones make ________________ bonding to negatively charged _____________ possible
electrostatic, phosphate
Supercoiled DNA and topoisomerases are found in _____________
eukaryotes
viral and bacterial chromosomes are much smaller than ________ and contain less _____________
eukaryotic chromosomes, genetic information
Electron microscopic observations of chromatin revealed...
fibers composed of linear array of these spherical particles (Nucleosomes)
Histone tails provide potential targets along the chromatin ____________ for _______________ modifications
fibers, chemical
Lampbrush Chromosomes are sites of _______ __________
gene activity
Topoisomerases wind or unwind _______ before _____________ ends
helix, resealing
phosphorylation adds phosphate groups to _________________ groups of amino acids ___________ and ___________
hydroxyl, serine and histidine
in heterochromatin, condensed areas are mostly ____________
inactive
heterochromatin is genetically __________ meaning that it lacks _________ or contains repressed ___________
inactive, genes, genes
viral genetic material is __________ until released into ______ _______
inert, host cell
during _____________ , chromatin is dispersed throughout nucleus
interphase
phosphorylation enzyme is _______________
kinase
Lampbrush Chromosomes are very _______ with extensive ________ ___________
large, DNA looping
Polytene Chromosomes can be visualized by...
light microscopy
the viral Chromosome Structure is able to package....
long DNA into a small volume just like bacteria and eukaryotic cells
histones contain large amounts of ____________ and __________
lysine and arginine
methylation enzyme is ______________
methyltransferase
Polytene chromosomes can be seen in...
nuclei of interphase cells
Polytene Chromosomes represent _________ ___________ and are ___________
paired homologs, unusual
lampbrush chromosomes are similar to...
polytene chromosomes puffs
histones are __________ charged proteins associated with ____________ DNA in ____________
positively, chromosomal, eukaryotes
Lampbrush Chromosomes are easily isolated in...
prophase I of meiosis
Unlike viral chromosomes, bacterial chromosomes are...
readily replicated and transcribed
To allow replication and gene expression, chromatin must...
relax compact structure, exposure regions of DNA to regulatory proteins, have a reversal mechanism for inactivity
Polytene chromosomes undergoes many rounds of _______________ without __________ ____________ or _______________ ____________
replication, strand separation or cytoplasmic division
Polytene chromosomes are found in various tissues (4 types) : __________, ___________, ___________ and ___________ _____________
salivary, rectal, midgut, and excretory tubules
heterochromatin appear _________ during interphase, why?
stained, because it's so dense
____________ facilitates compaction of DNA
supercoiling
in both prokaryote and eukaryote DNA, Replication and transcription create...
supercoils downstream as double helix unwinds
chromatin are formed when eukaryotic chromosomes ___________ and ___________ during ______________
uncoil, decondense, interphase
euchromatin appears ____________ during interphase
unstained
lampbrush chromosomes are found in most ____________ _____________ and ____________ of some insects
vertebrate oocytes and spermatocytes of some insects
