E. 6 Transcription and gene expression Flashcards
Describe RNA
DNA sequences are copied in larger numbers as ribonucleic acid: RNA
Messenger RNAs (mRNAs) code for proteins
There are a large number of genes for non-coding RNAs that have other functions, eg ribosomal RNA
What are the three steps in protein production for the regulation of gene expression
-Regulation of transcription
-Regulation of mRNA processing and decay
-Regulation of translation
Describe structure of RNA
RNA can fold into secondary and tertiary structures by internal base pairing
what are the differences in RNA and DNA
-RNA is chemically less stable than DNA, especially in alkaline condition
-DNA has a 2’ deoxyribose sugars, while nucleotides in RNA has ribose sugars, making RNA less stable
-RNA has uridine instead of thymidine phosphate residues
-RNA is usually single stranded, while DNA is usually a double helix
-Single stranded RNA can fold into diverse structures and perform similar functions to proteins, including enzymes
How does RNA polymerase know when and where to start?
-no primer
-promoter sequence in DNA is needed to direct to right spot which is mediated by transcription factors
-recruitment of RNA polymerase also requires chromatin modification, including relocation and modification of the nucleosomes
how is RNA polymerase regulated in eukaryotes?
- Chromatin rearrangement- open conformation and low nucleosome density permit RNA polymerase access
- Regulation of RNA polymerase recruitment RNA polymerase has to be positioned at the transcription start site of the gene
Describe transcription factors
-Transcription factors are DNA binding proteins that recognise specific DNA sequences in the genes they control. Every gene has a unique combination of transcription factor binding sites
what structure do transcription factors have?
modular structure (one note)
how can transcriptional activators work?
by recruiting coactivator proteins that modify chromatin (more info on one note)
Describe modifications on the nucleosome
- long lasting and can be copied during DNA replication. This means that cells inherit a memory of which genes were activated long after the stimulus is gone
-Chromatin modifications can sometimes even be passed on to the next generation
what is epigenetics
study of chromatin modification
Describe basal transcription factors
bind to nearly all genes, not gene specific therefore do not cause gene specific regulation
Gene specific transcription factors cause…
gene regulation
why is transcription regulation gene specific?
because different combinations of transcription factors are used
Describe drugs targeting epigenetic regulation
-widely researched for cancer, diabetes, neurological and inflammatory diseases
-Many are natural compounds, indicating that our food commonly contains such activities
