101: Lec 23

What is the first level that eukaryotic gene expression is regulated?

Chromatin modification

What is heterochromatin and euchromatin?

Highly condensed DNA and less condensed DNA respectively

How do we make DNA in chromatin available for transcription?

Adding acetyl groups to the histone tails to loosen chromatin structure (acetylation)

What is methylation of chromatin?

Adding methyl groups to histone tails that makes chromatin more condensed

What is epigenetic inheritance?

When the available and unavailable regions of DNA remain so in the 2 new daughter cells after cell division

What is the second level at which eukaryotic gene expression can be regulated?

At initiation of transcription

How does initiation of transcription regulate gene expression?

Via transcription factors, which start and regulate transcription. Some of them can promote or repress transcription, and this is the most frequent way in which cells control gene expression

What is the third level at which eukaryotic gene expression is regulated?

RNA processing

How does RNA processing regulate gene expression?

Different mRNAs are made from the same pre-mRNA

What is the fourth level at which eukaryotic gene expression is regulated and give an example?

Translation, binding of proteins to 5’ end of mRNA to prevent binding to small subunit

What is the fifth level at which eukaryotic gene expression is regulated?

Degradation of mRNA

Describe the time of mRNA degradation for pro and eukaryotes

Within minutes, and hours-weeks respectively

What is the stability of mRNA determined by?

The nucleotide sequence of UTRs in mRNA

What is the sixth (final) level at which eukaryotic gene expression is regulated?

Protein processing and degradation

Describe what is regulated in protein processing and degradation

Glycosylation/phosphorylation are required to make the final functional protein (regulated). Trafficking of proteins to correct organelles is also regulated

What is the length of time that a protein functions regulated by?

Selective degradation, which is marked by ubiquitin

What % of the human genome codes for protein?

1.5%

What % of DNA in human cells is transcribed into pre-mRNA?

75%

How do non-code RNA segments regulate gene expression?

Influencing chromatin packaging, translation and mRNA degradation

What is a totipotent cell and give an example?

No loss of genetic information and ability to make a clone of the animal e.g. mammary cells