Gene duplication
by recombination or errors in replication
Gene Variation
by accumulating mutations
Gene clusters
group of adjacent genes that are identical or related
tandem repeated genes
Unequal crossing-over (nonreciprocal recombination)
results from an error in pairing and crossing-over
- produces on recombinant with a deletion of genetic material and one with a duplication
Unequal crossing-over rearranges gene clusters BUT..
rare during an individuals lifetime, but significant over the course of evolution
Gene number can be changed by...
unequal crossing-over
HbH disease
disproportionate amount of the
abnormal tetramer ?4 relative to the amount of normal
hemoglobin (?2?2)
hydrops fetalis
absence of the hemoglobin ? gene;
fatal
Hb Lepore
unusual globin protein resulting from
unequal crossing-over between the ? and ? genes
Hb anti-Lepore
fusion gene that has the N-term of ?globin and the C-term of ?-globin
Hb Kenya
fusion gene of the A?- and ?-globin genes
Nontranscribed spacers
#NAME?
Genes in an rDNA cluster all have an...
Identical sequence
nucleolus
- discrete region of the nucleus where
ribosomes are produced ? high transcription rate
nucleolar organizer
#NAME?
Highly repetitive DNA, satellite DNA or Simple sequence
DNA
short repeating DNA sequences, no coding function
present in MOST eukaryotic genomes
Often the major constituent of centromeric Heterochromatin
minisatellite
10-100 bp
microsatellite
<10 bp
Euchromatin
Most of the genome in the interphase nucleus
less tightly coiled than heterochromatin
contain most of the active or potentially active single-copy genes
in situ hybridization
used to identify the location of highly repetitive DNA
Satellite DNA is useful for DNA profiling because..
Analysis of the differences between individuals
based on restriction fragments that contain short
repeated sequences, or by using PCR