1. Regulation of Gene Expression – Part II
Spring Althoff Reference: Mader & Windelspecht Ch. 13)
Lec 19
• Eukaryotic Regulation

2. Eukaryotic Regulation
With few known exceptions….____________ of a multicellular eukaryote has a complete complement of genes.
Cell type differences (i.e., muscle vs. nerve vs. liver vs. etc.) result because only a certain set of genes is “___________” in the ___________…thus, a different set of proteins are “active” in the cytoplasm.
There are 5 primary levels of control: 3 pertain to the __________, 2 of them pertain to the _____________

3. Eukaryotic Regulation – 5 types of control1
Chromatin Structure – in the nucleus
Transcriptional Control – in the nucleus
Posttranscriptional Control – in the nucleus
Translational Control — in the cytoplasma
Posttranslational Control – in the cytoplasma 2 3 4 5

4. 1
Nucleus 2 3
Cytoplasma 4 5

5. Type: Chromatin Structure1
Chromatin packing is used as a way to keep genes turned ____. If genes are not accessible to ________________, they cannot be ___________.
Chromatin structure is one method of __________ ___________ = transmission of genetic information “__________” the ______________ of a gene.
Chromatin is a “stringy” variety of proteins material… most prevalent during interphase of the cell cycle

6. Type: Chromatin Structure1
One class of DNA-associated proteins are ____________. They play an important role in ________________ of DNA.
Without histones, DNA could not fit inside the nucleus. Each human cell contains about 2 meters of DNA…yet the nucleus is only 5-8 цm in diameter.
_______________ chromatin = ______________

7. Nucleus with staining showing… heterochromatin and euchromatin
nucleolus

9. nucleosome DNA Unpacking _____________ promoter chromatin remodeling1
chromatin
remodeling
___________
promoter 2 3
DNA to be __________

10. Type: Chromatin Structure1
Heterochromatin is not transcribed…
Heterochromatin does not permit access by RNA polymerase
Genes contained by heterochromatin __________ _______ get transcribed…therefore they are not expressed
Example: Barr body in mammalian females (XX): chromatin adheres to inner edge of the nuclear membrane—resulting in one inactive X chromosome (i.e., produces no products)

11. Type: Chromatin Structure1
__________ Inheritance: sometimes caused by histone modification…changes that result not in sequence of DNA nucleotides.
Epigenetic inheritance term is not restricted to the genes themselves causing variation.
Epigenetic inheritance may explain unusual patterns of inheritance …and may play a role in growth, aging, and cancer.

12. Type: Transcriptional Control2
This is considered the _____________ of the 5 control levels
Keep in mind that the first step towards transcript is availability of DNA
A eukaryote may have many different types of _________________—proteins that help regulate transcription by assisting RNA polymerase to bind to the _______________.
There may be __________________ transcription factor active at a single promoter…thus, the absence of one can prevent transcription from taking place

13. Type: Transcriptional Control2
Even with all transcription factors present, transcription might not begin without the presence of a DNA-binding protein called a _____________ ______________
Transcription activators bind to regions of the DNA called _______________.
Enhancers may not be located near promoters…
“Distance” reduced with _____________ in the DNA

14. _________________________1
enhancer 2
transcription
activator 3
_________________________

15. Type: Posttranscriptional Control
Occurs in the nucleus
Includes alternative mRNA splicing and controlling of the _____ with which mRNA leaves the nucleus
During pre-mRNA splicing, ________ (non-coding regions) are excised…and ________ (expressed regions) are joined together to form an mRNA.
Result: if an exon is _________, it may be is excised along with flanking introns…the result…
….the ___________ has an altered sequence and the protein it encoded is altered
Example: in thyroid, a slightly different calcitonin than what the hypothalamus produces. 3

16. what happens in the nucleus in the cytoplasma what happens
Protein product 1
Protein product 2

17. Type: Translational Control
Occurs in the cytoplasma
Happens __________ a protein product is made
Associated with activity of the mRNA for translation at the ______________
Affected by the presence…or…absence… of the 5’ cap and the length of the poly-A (i.e., adenine nucleotide) tail at the 3’ end…this can affect the whether a) __________________…or for _____ _____ the mRNA is active.
Example: persistence 5’ end caps and long 3’ poly-A tails long-life of mRNAs that code for hemoglobin in mammalian red blood cells 4

18. Type: Posttranslational Control
Occurs in the cytoplasma
Begins once the __________________________ and become active.
It represents the last chance the cell has for influencing gene expression
This highlights the fact that not all proteins are “active” after synthesis. Value of this: a protein is only activated when it is appropriate to do so. Example: bovine proinsulin is “held” as such before special bonding process that results in “active” insulin. 5

19. Type: Posttranslational Control
Length of time a protein remains active in a cell usually regulated by ____________ = enzymes that breakdown proteins.
Proteases usually confined to ____________ or special structures called _________________. 5

20. Type: Posttranslational Control
For a protein to enter a proteasome, it has to be “tagged” with a signaling protein recognized by the proteasome’s cap.
When the cap recognizes the tag, it opens up and allows the protein to enter the core of the structure where it is ___________________________.
This is gene expresssion control” because it regulates the amount of protein product in the cytoplasma 5

21. Posttranslational Control: “________”5
Which leads to ________ into proteasome
where…

22. Posttranslational Control: “___________”5
…break down to _______________________.

23. modification of DNA via
In summary….
modification of DNA via
chromatin structure
transcriptional
posttranscriptional
translational
posttranslational
transcription
translation
mRNA
protein
DNA