Q10: Final Review: GENETICS

Comparative Genomics

The comparison of genomes both within and between species

Gene Duplication

arises via unequal crossovers due to repetitive elements

Alternative splicing

ex. gene duplication of Hox genes

Paralogs

genes that are a result of a duplication event within the same genome

Exon Shuffling

Exons from the 2 or more different genes are combined gene/spicing pattern

Can also arise via unequal crossovers

Multigene Families

Group of genes with similar sequence and function

Duplication of genes allows for speciation of function
Different tissues have different functional needs = allows specialization without increasing gene number = different variants

Dispersed Multigene

group of relates genes that are scattered across different location in the genome

Often on different chromosomes

Ex. Actin genes (simpler structure)

Clustered Multigene

Group of related genes that are located next to each others (or very close) on the same chromosome

Usually arising from tandem duplication

Ex. Globin genes

Pseudogene

Arises from gene duplication or mutation of a functional gene

Same intro-exon structure as original gene

Promoter usually present (inherited from original gene)

May retail regulatory sequences

Processed Pseudogenes

Arises from reverse transcription of mRNA and reintegration into the genome

No intron cause derived from spliced mRNA → processed

Promoter is absent or incomplete

Lacks regulatory sequences

Reverse Transcription

Insertion of cDNA by a retrotransposon-encoded reverse transcriptase into a new place in the genome

Gene Fusion

Fusion or rearrangement of existing genes through genomic deletions or new splicing signals

De Novo Derivation

New coding genes can be derived de novo from intronic or intergenic sequences

Horizontal Gene Transfer

movement of genes from one species to another

• Common mechanism in bacteria and archaea