Polyploidy and Epigenetics

Polyploidy

Possession of two complete sets of chromosomes. Caused by non-disjunction during mitosis or meiosis. Heritable.

Autoployploidy

Multiple sets from 1 species

Allopolyploidy

Multiple sets from more than one species

Give example of polyploidal animals

Tetraploid - Salmonidae fish, Xenopus leavis frogs

Octoploid - Acipenser sturgeon

Dodecaploid - Xenopus ruwenzoriensis frog

Give examples of polyploidal crops

Triploid - apple, banana, citrus, ginger, watermelon

Tetraploid - apple, durum or macaroni wheat, cotton, potato

Octoploid - strawberry, dahlia, pansies, sugar cane

Benefits of polyploidy

Can make plant, leaves, flowers or fruit bigger

More resistant to recessive allele effects

What is epigenetics?

Chemical reaction that switch part of the genome on and off.

What is a transcription factor?

Binds to DNA at a binding site and regulates the production of protein from a gene

DNA methylation

Determines tightness of chromatin structure.

Occurs at CpG islands

C is methylated

Can lead to specific genes not being transcribed. Prevents binding of transcription factors to promote regions.

Histone modification

Addition of methyl, acetyl etc groups to the histone.

Condenses chromatin structure.

Condensed chromatin blocks transcription factors from accessing DNA

miRNA

MircoRNA produced by cells to regulate gene’s translation.

Perfect match → mRNA degradation

Imperfect match → translational repression