Chapter 9: 9.2 Horizontal Gene Transfer in Bacteria Flashcards
Lateral gene transfer
Give an example of it happening in eukaryotic cells
Movement of genes from the mitochondria and chloroplast into the nucleus over evolutionary time
What are the steps to lateral gene transfer?
- Gene copy is made
- Gene is sent to the nucleus and incorporates into the nuclear genome
- Original gene in the mitochondria or chloroplast is degraded
What are reasons that genes move due to horizontal gene transfer?
- To get away from potential damage caused by reactive oxygen species
- Nuclear genes have more expression regulation
- Nuclear genes can undergo sexual recombination
What are ROS?
Reactive oxygen species
* Oxygen moecule with an extra electron
* Very reactive
Where are ROS produced?
Produced by oxygen removing (oxidizing) and electron from Complex IV in the mitochondria
What is the benefit of nuclear genes undergoing sexual recombination?
Increased variation
What are reasons that not all genes have moved to the nucleus due to horizontal gene transfer?
- Some genes need to be close by where their proteins are needed
- Some genes are needed to replicate the organelle, thus required to stay in the organelle
- Takes energy to import proteins from the cytoplasm into the organelle
- Evolution is constantly occurring
How does organelle DNA move to the nucleus?
Through direct DNA transfer
* Possibly through cDNA
Describe:
The process of organelle DNA moving to the nucleus
Organelle breaks down, releases DNA into the cytoplasm
1. Nuclear envelope breaks down during division, nucleus reforms around organelle DNA and nDNA
2. Organelle DNA moves through nuclear pores into the nucleus
Once in the nucleus, gets incorporated into the DNA through NHEJ
What are the two pieces of evidence within the nDNA for organelle DNA?
- NUPT
- NUMT
NUPT
Nuclear plastid sequence
* Sequences in the nucleus that originated from chloroplasts
NUMT
Nuclear mitochondrial sequences
* Sequences in the nucleus that originated from the mitochondria
