BIOL 142 Lecture Notes - Lecture 20: Prokaryote, Lac Operon, Alternative Splicing
Biology 142- Lecture 20- Genomics Continued 2& Gene Regulation
Transposons
• Transposons are DNA in the genome that can change its position
• Because transposons can change location, they can also create or reverse mutations
based on where they inset along the genome
o This could be potentially dangerous because mutations can lead to illness and
disease
• Transposons can alter cell genetic identity
• The genome also increases in size throughout our life span because of transposons
• 95-99% of the genome has no obvious function (these portions of the genome are
scattered throughout)
• 50% of the genome is repetitive sequences
• 45% of the genome is transposons
o 21% are long interspersed nuclear elements/long interspersed elements (LINE)
▪ LINEs are transcribed into mRNA and translated into protein that acts as a
reverse transcriptase. The reverse transcriptase makes a DNA copy of the
LINE RNA that can be integrated into the genome at a new site.
o 11% are short interspersed nuclear elements/short interspersed elements (SINE)
▪ SINEs are transcribed into mRNA and translated into protein that acts as
a reverse transcriptase. The reverse transcriptase makes a DNA copy of
the SINE RNA that can be integrated into the genome at a new site.
• Gene number and alternative splicing also contributes to human complexity
o This doesn’t create more genes, rather it results in more gene products
o Alternative splicing is a process where a gene can code for multiple proteins
o 1 gene can give approximately 3 transcripts (3 proteins)
Gene Regulation
• gene regulation is used by cells to increase or decrease the production of specific gene
products
• there are different levels of gene regulation according to the central dogma (DNA-
(transcription)->RNA-(translation)->Protein
o transcriptional control
▪ this is the most effective, slower, permanent gene regulation response
o translational control
o post-translational control
▪ requires more resources because it has to work with proteins and mRNA
that have already been made
