The Dynamic Genome Flashcards
(20 cards)
organsims/cells contain one (haploid) or two (diploid) sets of chromosomes
euploid
have more than two sets of chromosomes (triploid, tetraploid, pentaploid, etc), or can have fewer sets than they should (e.g. monoploid)
polyploids
the addition or loss of one chromosome in the set
aneuploidy
a failure in chromosome segregation
nondisjunction
extra set of chromosomes comes from parents within the same species, which can happen through complete nondisjunction, two sperm fertilize one ovum, or induced with colchicine (a microtubule inhibitor)
autopolyploidy
extra set of chromosomes come from two different (closely related) species
allopolyploidy
2n +1
trisomy
2n -1
monosomy
the relationship between the number of copies of gene and the number of transcripts produced for that gene
gene dosage effect
X chromosome inactivation occurs randomly in each cell during development.
The inactive X is found in a “Barr body” in the nucleus.
Nearly all genes will be repressed
X Chromosome Dosage Compensation
Move directly from one position to another within the genome; an enzyme known as transposase cuts a DNA transposon out of one location and inserts it in another
DNA transposons
move in the genome by being transcribed to RNA, reverse transcribed to DNA by reverse transcriptase, and inserted into the genome by integrase
Retrotransposons
functional; contain genes for reverse transcriptase and integrase
autonomous
nonfunctional; lacks reverse transcriptase and/or integrase
non-autonomous
mechansims prevent transposition in germline cells
genome surveillance
result in gene dosage changes
unbalanced rearrangements
do not result in gene dosage changes
balanced rearrangements
missing alleles can result in expression of recessive phenotypes
pseudodominance
Inversions that include a centromere
pericentric
inversions that do not include a centromere
paracentric
