Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
|
Gene Expression
|
transfer of information from genes to an ultimate protein that is functional
|
|
|
Regulatory Proteins (trans)
|
bind to the promoter to regulate RNA Pol, TF, activators and repressors
|
|
|
Negative Regulation (trans)
|
- Bound repressor inhibits trans
- molecular signal causes dissociation of regulatory protein form DNA - needs a signalling molecule which binds to operator, repressing trans |
|
|
Positive regulation (trans)
|
- binding of molecular signal causes the activator to bind and facilitate transcription
|
|
|
Regulatory Sequence
|
- have DNA binding motifs
- interact with specific sequences (activator/operator) - specific; depends on H-bond donor/acceptors - most common AA involved: Asn, Gln, Glu, Lys, Arg |
|
|
Helix-turn-Helix Domain
|
20 AA long with 2-alpha segments - onesegment is “recognition Helix”
|
|
|
Zinc Finger Domain
|
-30 AA long
-loops are coordinated b/w Zn2+ -DNA binding is weaker ***Thusproteins may have more than one Zn finger - Can act as an RNA-binding protein |
|
|
Homeodomain
|
Found in eukaryotes
- 60 AA long - Similar to H-T-H |
|
|
Leucine Zipper Domain
|
Leu occurs every 7th position
- Interact with proteins - Partially interacts with DNA (Lys/Arg) |
|
|
Helix-Loop-Helix
|
Only one Leu residue
Interact with proteins Partially interacts with DNA (Lys/Arg) |
|
|
Eukaryotic Gene expression
|
- Access to promoters is restricted by chromatinstructure
- Positive regulation most common - Transcription and translation separated bynucleus (more complex regulation) |
|
|
Chromatin
|
DNA+ histones (H1, H2A, H2B, H3, H4)
|
|
|
Transcriptionally Active Chromatin
|
-Deficient in H1
- enriched with H3.3 and H2AZ |
|
|
Histone Modification
|
SWI/SNF proteins needed
- Methylation (cytosine in CpG) - phosphoryltion - acetylation (regulated by HATs and HDACs) - ubiquination - sumoylation |
|
|
HMG
|
High Mobility Group
- help in activation of regulatory proteins that help to assemble pre-initiation complex |
|
|
UAS
|
Upstream Activator Sequence
- turned off by repressors |
|
|
Eukaryotic Gene Expression
|
Mediator modifies/remodels enzymes
- then remodels complex TBP binds to TATA - forces Pol-II to bind there |
|
|
Activation Domains in Trans.Factors
|
“---“ Acidic AAs--> Asp and Glu
“ppp”--> Proline “QQQ”--> Gln |
|
|
Regulation of Trans. Factors
|
- Steroids and vitamins
- Covalent modifications Nuclear receptors mainly with multiple domains |
|
|
Alternative Splicing
|
A gene can have 2 or more Poly-A sites
- can lead to cleavage in different ares, making completely different proteins (i.e. calcitonin and CGRP) |
|
|
miRNA: Regulation
|
Silence genes by binding to mRNA
- results in mRNA degradation or trans. inhibition - done by endonucleases Drosha and Dicer |
|
|
siRNA: Regulation
|
Bind to mRNA and silence
- constructed by Dicer to make stRNA - Dicer makes double stranded RNA and makes siRNAs |
|
|
Hormonal Gene Expression: Hsp70
|
Hormone comes into NR-Hsp70 complex
- Hsp70 removed to leave NR-hormone to dimerize - binds to HRE on DNA near Pol II - turns target gene ON - makes mRNA with specific changes in cell fun like heat-shock proteins |
|
|
Hormonal Gene Expression: corepressor
|
Hormone takes corepressor off DNA which have it currently turned OFF
- hormone binds to HRE near Pol II - turns gene ON - change in cell fxn |
