Various types of expression phenomenon present in eukaryotic genome.

1. GENE EXPRESSION
IN EUKARYOTES
Presented by
Shubhajit Roy
MSc (Biotechnology)
RA2332001010094

2. Prokaryotes vs. Eukaryotes
Prokaryotic transcription and translation occur simultaneously in the cytoplasm, and regulation
occurs at the level of transcription. In eukaryotes, transcription and translation are physically
separated, and gene expression is regulated at many different levels.

3. Eukaryotic Gene Regulation
Epigenetic
Modification
Transcriptional
Control
Post-
transcriptional
Modification
Translational
Control
Post-
translational
Control

4. Epigenetic Control
In each chromosome, DNA is wound
around histone proteins to pack it into the
nucleus of a cell.
Nucleosomes can slide along DNA. (A) When
nucleosomes are spaced closely together, transcription
factors cannot bind and gene expression is turned off.
(B) When nucleosomes are spaced far apart,
transcription factors can bind, allowing gene
expression to occur

5. Transcriptional Control
Each gene has a promoter upstream of the coding
sequence. The promoter binds to transcription
factors and helps RNA polymerase to bind and start
transcription.
Many genes also have upstream enhancers.
Enhancers bind activators, bend around, and help
RNA polymerase start transcription.

6. Post-transcriptional Modification
Before a RNA can be translated, introns must be removed
by splicing. Pre-mRNA can be alternatively spliced to create
different proteins.
The protein-coding region of mRNA is flanked by 5′
and 3′ untranslated regions (UTRs). RNA-binding
proteins at the 5′ or 3′ UTR influence the stability of
the RNA molecule.

7. Translational Modification
• Translation can also be regulated at the level of binding of the mRNA to the
ribosome.
• Once the mRNA bound to the ribosome, the speed and level of translation
can still be controlled.
• An example of translational control occurs in proteins that are destined to
end up in an organelle called the endoplasmic reticulum (ER).
• The first few amino acids of these proteins are a tag called a signal
sequence.
• As soon as these amino acids are translated, a signal recognition particle
(SRP) binds to the signal sequence and stops translation while the mRNA-
ribosome complex is shuttled to the ER.
• Once they arrive, the SRP is removed and translation resumes.

8. Post-translational Control

9. Protein Degradation
Ubiquitination: Proteins with ubiquitin tags are marked for
degradation within the proteasome.
Methylation
Acetylation
SUMOylation
Glycosylation
Formylation
Oxidation
Hydroxylation
Other types of PTM

10. Thank You