The Central Dogma Flashcards
What is true of cells and their expression of genes?
Often, cells are always expressing genes, but at different amounts and rates, due to a difference in the ability of specific transcription factors.
What are 5 general places to regulate gene expression?
Chromatin remodeling, transcription factor regulation, mRNA splicing/maturation, destruction of mRNAs, or protein level phosphorylation
Nucleosome
Histone octamer surrounded by DNA
Inactive genes [methyl/acetyl]
Methylated DNA in promoter, and methylated, deacetylated histones
Active genes
acetylated, non-methylated histones
What do acetyl groups do to histones?
It spreads them apart, unwinding the DNA
Promoter
sequence that starts the sequence of an active gene
What are CpG islands?
They are places where a transcription factor binds and activates a promoter to transcribe the active gene
Where is DNA methylation high?
In primordial germ cells, right before fertilization, and at the embryo stage.
General transcription factors
bind to gene promoters and organize the transcriptional machinery
Regulatory transcription factors
bind to enhancers to make transcription more or less efficient
Where is the TATA box located?
In the promoter sequence.
What must be true before RNA polymerase can bind to the gene?
Several General transcription factors must be present
How to regulatory transcription factors interact with enhancers?
They can create a 3d complex such as the mediator complex which more easily allow RNA polymerase to bind.
Where in relation are enhancers located to the active gene?
Usually far away
What are two properties of regulatory transcription factor binding that promotes differentiation and variation?
Combinations of transcription factors, and cascades can induce variability
How do transcription factors ensure differential gene expression?
Specific tissues have specific transcription factors that activate tissue specific enhancer sequences
MyoD1 [explanation, sufficiency/necessity]
Can induce differentiation into muscle. is sufficient, but not necessary, as this works with myf5 as well
What is the technical name of something that promotes differentiation into muscle?
myogenic factors
Pax6
induces differentiation into eye tissue
How can you study transcriptional regulation without changing the gene’s natural function?
Fuse the regulatory DNA associated with a gene to a “reporter” e.g GFP
Splicing
taking specific exons out of the nRNA , can make many combinations.
5’ cap
translatability
3’-UTR
mRNA localization, regulation of translation
poly A tail
mRNA stability, translation
Polyadenylation element
AAUAAA catalyze addition of As to the tail.
Where do RNAs usually end up in the Oocyte?
In the vegetable pole
What is nanos mRNA
mRNA that is being currently translated
What section of mRNAs attach to microtuble motors?
The 3’-UTR region
Which direction do kinesins travel?
Toward the posterior end of the cell [Positive]
Which direction do dyneins move?
Toward the anterior end of the cell [Negative]
What do bicoid mRNAs attach to? [which motor]
Dyneins
What do oskar mRNAs attach to? [which motor]
Kinesins
What are two ways that mRNA translatability can be affected?
The Maskin/CPEB/4E complex, and the Bicoid/Caudal complex.
How is the Maskin/CPEB/4E complex changed after fertilization?
CPEB is phosphorylated, poly(A)polymerase is recruited, building As which can bind poly(A) binding protein(PABP), which can finally initiate translational cofactors at the 5’ end.
The maternal to zygotic transition varies in time between species [true/false]
true
What is the name of small RNAs that regulate mRNAs?
micro RNAs, [miRNAs]
First stage of a microRNA
pri-miRNA (primary micro RNA)
Pri-miRNA is processed to ____ by ____ in the second step
Pri-miRNA is processed to pre-miRNA by Drosha
Pre-miRNA is processed by ____ into short double stranded RNA duplexes.
Dicer
RISC choices
if the mRNAs match, then the mRNA is destroyed. If the match is inexact, translation is blocked.
Degradation of proteins is marked by ____ to be sent to the ____ for destruction
Degradation of proteins is marked by ubiquitins to be sent to the proteasome for destruction
What famous signaling pathway that we have been studying uses proteasome?
Wnt B catenin signaling. In the absence of Wnt signaling, GSK-3, and APC add ubiquitins to Beta catenin, destroying it.
