lecture 10 Flashcards
chromosomal modifications
a change in the total chromosome number
how can chromosomal modifications occur?
deletion or duplication of gene segments, or rearrangements of genetic material among or among chromosomes
what are the types of chromosome mutations?
deletion, duplication, inversion, and translocation
aneuploidy
monosomy: loss of a single chromosome from a diploid genome
trisomy: gain of a single chromosome
euploidy
complete haploid sets of chromosomes are present
polyploidy
more than two sets of chromosomes are present
what is autopolyploidy?
the addition of one or more sets of chromosomes identical to the haploid complement of the same species
what its allopolyploidy?
combination of chromosome sets from different species as a consequence of hybridization
autopolyploidy
each identical set of chromosomes is identical to the parent species
how does autopolploidy arise?
a diploid gamete is produced or two sperm fertilize one ovum (rare)
what is autopolyploidy more prevalent in?
natural population; produces balanced gametes
in autopolyploidy, is each additional set of chromosomes identical or different to the parental species?
identical
triploids
often genetically unbalanced gametes with odd numbers of chromosomes
tetraploids
(AAAA and so on), more likely to produce genetically balanced gametes
diploid gametes
produced when chromosomes fail to segregate during meiotic division
what forms a triploid zygote?
two sperm fertilizing an ovum
what does allopolylpoidy result from?
hybridizing two closely related species, may be sterile
do allopolylpoidy organisms have homologous chromosomes?
no
