Lecture 12 Flashcards
(30 cards)
chromosomal duplications are
repeated segment of chromosome
how do duplications arise
through replication error prior to meiosis
through unequal crossing over between synapsed chromosomes during meiosis
what are three results from duplications?
gene redundancy
phenotypic variation
source of genetic variability during evolution
redundancy is
ribosomal RNA
redundancy
multiple copies of genes code for rRNA
is a single copy sufficient in redundancy?
no
DNA that codes for rRNA is called
rDNA
what is essential in abundance in a cell to support protein synthesis
gene product
how do new genes arise?
non-functionalization
neo-functionalization
sub-functionalization
inversions are
rearrangement of linear gene sequence
during inversions the segment of a chromosome turns how far within a chromosome
180 degrees
is there a loss of genetic information in inversions
no
how many breaks do inversions require
2
when does the chromosomal loop form
prior to breakage
what do inversions create to close together and rejoin
sticky ends
what may the inverted segment not include
centromere
paracentric inverision
does not include centromere
pericentric inversion
includes the centromere
when does linear (normal) synapse not occur
it is not possible if only one member of homologous pair has inverted segment
inversion heterozygotes are
organisms with one inverted chromosome and one non-inverted homolog
pairing between inversion heterozygotes require an
inversion loop
how many recombinants does a crossover of paracentric inversions produce
two- dicentric and acentric
dicentric chromatid
two centromeres
acentric chromatid
lacking a centromere