Chapter 11 Flashcards
What are the 4 differences between eukaryote and prokaryote transcription?
1.) More genes that are far apart
2.) 3 RNA polymerase types
3.) Transcription happens in the nucleus
4.) DNA is packaged into chromatin
What do general transcription factors do?
They bind sequences in the promoter.
What is the preinitiation complex?
Complex RNA pol II and general transcription factors.
What is mRNA capping?
Adding methylated guanine on the 5’ end of the mRNA to protect decay from exonuclease.
What is mRNA polyadenylation?
Conserved sequences in the 3’ UTR signal for cleavage of RNA from RNA pol II and additional of the poly-A taile protects from decay.
How are different proteins encoded by splicing?
Cutting introns out or leaving them in certain areas of the genes therefore the proteins made are varied.
What is the difference between transcription factors and coregulators?
Coregulators cannot bind to DNA directly but transcription factors can.
Transcription factors and coregulators can either be?
Repressors or activators
What is the core promoter?
A region surrounding the transcription start site where the transcription factor binds.
What are coregulators?
These are factors that can bridge the interaction between transcription factors and RNA pol II.
What are the 2 required elements for transcription?
1.) DNA binding domain
2.) Activation/repression domain
What are the 2 optional elements for transcription?
1.) Dimerization domain
2.) Ligand binding domain
In the absence of glucose other than lactose what carbon source can be used as energy?
Galactose
Which enzymes are used to import and metabolize galactose?
Gal2
Gal1
Gal7
Gal10
What are the regulatory proteins that can regulate transcription of the enzyme enoding genes?
Gal4
Gal3
Gal80
What happens when galactose is absent?
The following are not expressed:
Gal2
Gal1
Gal7
Gal10
What happens when galactose is present?
The following are expressed:
Gal2
Gal1
Gal7
Gal10
Which of the following Gal are always expressed?
Gal4
Gal3
Gal80
What is the relationship between Gal4 and Gal80?
Gal80 is the repressor for Gal4.
What happens to Gal3 when galactose is present?
It undergoes conformational changes.
What are nucleosomes?
These are basic units of chromosomes that include histone proteins and DNA is wound around it because DNA is negatively charged and histones are positively charged.
What do histone octomers consist of?
H2A
H2B
H3
H4
(2 of each)
What do the histone tails do?
These tails are flexible and they interact with adjacent nucleosomes and proteins.
What is heterochromatin?
This is when the histones and the DNA are tightly compacted with one another.
What is constituitive heterochromatin?
This is when the chromatin is always tightly compacted.
What is facultative heterochromatin?
This is when the chromatin switches between very compacted to not.
What is euchromatin?
This is when the histone proteins loosen their compaction.
What is acetylation?
The addition of an acetyl group to the tails and it leads to reduce chromatin compaction and creates a protein binding domain called bromodomain for transcriptional co-activators that cannot bind to DNA directly.
What is HAT?
Histone acetyltransferase which adds the acetyl groups and makes the compaction euchromatin.
What is HDAC?
Histone deactylase which removes the acetyl groups and makes then more compacted heterochromatin.
What are the CPG islands in expressed genes?
Unmethylated
What are the CPG islands in unexpressed genes?
Methylated
What are CPG Islands?
These are regions that found in most gene promoters.
What do unmethylated CPG islands do?
Open chromatin and activate transcription.
What do methylated CPG islands do?
Close the chromatin and repress transcription.
What is the epigenetic mechanism?
Identical genes will be either active or inactive depending on the inheritance pattern from the mother or the father.
