Lecture 16 Flashcards
What is 90% of cells DNA and proteins dedicated to?
regulation
What are examples of signals?
intracellular or extracellular signals
What are examples of sensors?
Surface receptor enzymes
What is an examples of analysis of a cell?
coincidence detectors
What is the final response of the cell?
Transcription, enzymatic activity, protein stability, protein localization, cellular programs
What are cellular programs?
cell differentiation, enter or exit cell cycle, apoptosis
When is feedback regulation mainly used
Mainly used to regulate non-reversible reaction and to regulate key steps in metabolic pathways
What enzyme is involved in the synthesis of the nucleotides CTP, UTP and TTP?
aspartate transcarbamoylase
What helps regulate enzyme activity?
phosphorylation
What happens during acetylation?
removes the positive charge of the lysine and therefore modification affects interactions of the protein with other proteins or molecules (histones)
What helps with protein acetylation on lysine sidechains?
Acetyl-CoA
What is the ultimate “turn off” mechanisms
Degradation
What is the most common result of ubiquitination?
Degradation:
- proteasome
- lysosome
- autophagosome
What is the most complex regulation systems containing many phosphorylation, acetylation and ubiquitination sites?
p53
What drives vesicle formation on the ER membrane?
Sar 1
The assembly of what drives vesicle formation?
assembly of coat proteins
What is regulated by assembly/disassembly?
actin
What are transcription factors?
are DNA binding proteins that regulate transcriptioninitiation
What do transcription factors contain?
- DNA binding domains
- Transcription regulatory domains
Homeodomains form what?
form hydrogen bonds with nucleobases mostly via the major groove of the DNA
What do leucine zipper transcription factors form?
dimers
What does the term leucine zipper refer to?
the facts that the two helixes are dimerizing because of leucine side chains that form hydrophobic interface
What is the promoter?
transcription start site
What can be far upstream or downstream of transcriptional start site?
Enhancers
What interacts with seceral transcription factors/ regulators to regulate transcription initiation of a gene?
the mediator complex
What are repressors?
repressors are either physically competing for the DNA binding site or are suppressing transcription via the mediator complex
What is the transcription factor or regulator?
DNA binding protein that affects transcription initiation
What is the transcription activator?
DNA binding protein that increases transcription of a gene
what is a Transcription repressor?
DNA biding protein decreases transcriptionof a gene
What is an enhancer?
DNA sequence that is recognized by a transcription activator
silencer
DNA sequence that is recognized by a transcription repressor
What is a promoter?
DNA region usually upstream of the transcription start site that contains enhancer/silencer sequences and RNA polymerase binding site
What are the three different states of a gal promoter?
repressed, de-repressed and active
What state does inhibitor proteins keep the promoter in?
repressed state
What happens in the absence of glucose and galactose?
the repressors are not binding but the activator is blocked by Gal 80
What happens in the presence of galactose and absence of glucose?
The gal80 repressor is removed by the galactose binding protein Gal3 and the promoter is active
