Lecture 6 - Horizontal Gene Transfer and Transposable Elements Flashcards
What is horizontal gene transfer?
The movement of genetic material from one organism to another by other means than parent to offspring.
Give an example of how horizontal gene transfer has been detected.
In HMGCoA reductase gene in Archaean taxon, found to be acquired from bacterial lineage.
Where does yeast mitochondrial Heat Shock Protein 70 (hsp70) originate from?
S. cervisiae hsp70 more closely related to proteobacterial proteins than to other forms of yeast cells.
In what organisms does horizontal gene transfer normally occur?
Prokaryotes
Give an example of horizontal gene transfer in animals.
The coffee berry borer beetle has protein similar to mannanase, which breaks down a polysaccharide in coffee beans.
Mannanase has bacteiral origin.
Donor lineage is likely to be beetle’s own gut bacteria.
What kind of genes are transferred horizontally in prokaryotes?
- Pathogenicity factors
- Antibiotic resistance genes
What is a transposable genetic element?
A genetic element that can move from one position on a chromosome to another position on the same or a different chromosome, many laving a copy behind.
Who discovered transposable elements?
Barbara McClintock, 1940s/50s
What were transposable elements originally thought to be?
Junk DNA
What is the aleurone layer of maize?
The coloured protein layer, which is triploid
How are genes inherited in maize?
Two sets of alleles inherited from maternal line, and one from paternal line.
What is special about chromosome 9 of maize?
Readily breaks and is correlated with colour change.
What are the roles of the following alleles in maize?
a) C’
b) C
a) C’ = dominant allele, prevents colour from being exposed to aleurone layer.
b) C = recessive allele, leads to colour development in layer.
What are the roles of the following alleles in maize?
a) Bz
b) bz
a) Bz = dominant allele, produces purple colour.
b) bz = recessive allele, produces dark brown colour.
What is the role of the Ds allele in maize?
It is the genetic location where chromosome breakage occurs.
What kind of kernel would you expect with the presence of a C’ allele in maize?
Why might you not?
- A colourless kernel
- Due to breakage in some F1s, C’ is absent, resulting in pigmentation.
