Gene organisation and transcription 1 Flashcards
explain the basic differences between DNA and RNA
D- Thymine R - uracil
D - deoxyribose as base (derivative) R - ribose (parent)
D - double stranded R - single stranded
What is transcription
The process in which nucleotide information in the DNA is copied into RNA
List the major classes of RNA and the classes of RNA polymerases involved in synthesising each of these
tRNA - RNA polymerase 3
mRNA - RNA polymerase 2
rRNA - RNA polymerase 1
5S RNA - RNA polymerase 3
what is a transcription factor
protein that regulates the transcription of a gene, either increases it or decreases it
binds to DNA
what is a gene promotor
DNA sequence where the initiation complex assembles
elongation reaction requires this initiation step
Describe the basic process of transcription
DNA unzips - helicase
complementary ribonucleotides base pair 5’-3’ to the antisense strand
joined by RNA polymerase 2 - forming phosphodiester bonds
Types of transcription factors
Transcriptional activators - can activate gene expression
Transcriptional repressor - suppress gene expression
Act collectively to bring specific/developmental/inducible gene expression
What is the anatomy of the gene promotor
Transcription binding site - control rate transcription
TATA - initiation point - transcription - platform to make initiation complex
Describe the basal transcription complex
Transcription binding site - control rate transcription
TATA - initiation point - transcription - platform to make initiation complex
Describe the function of the basal transcription complex
allow RNA II Pol to be phosphorylated produce basal (low) level of transcription
Action of Transcription factors
bend DNA
interact with each other and DNA - modulate transcription
remodel chromatin - recruit enzymes that modify histones - acetylated histones are open, deacetylated histones are closed hyper/hypoacetylation correlates with gene expression
Factors affecting transcription factor expression
cell lineage external signals: hormones growth factors mechanical stress heat cell contact light touch voltage
What do we say about a gene that is used in a cell
it is expressed
What is the name of genes expressed in all cells
housekeeping genes
what are housekeeping genes used for
normal cell function and viability
What do we mean by gene expression
initial product is RNA
can be functional - tRNA, mRNA, snRNA
template - mRNA
occurs in nucleus
How is gene regulation involved in human disease
Mutated transcription factords in disorders
abnormal TF expression in cancer
Mutation affecting regulation of specific genes in human diseases
Inflammation and TF
IkB - inhibitor for NFkB
NFkB -TF for cytokines that produce inflammatory response
initiator of inflammation casue IkB to be broken down - NFkB leaves cell and cytokines are produced.
Asparin and inflammation
Aspirin stop break down of IkB
NFkB stays in cell
no inflammatory response
Transcription factors and leukaemia
TF mutated by translocation - Philadelphia chromosome
TF activated - growth of tumours
oestrogen and TF
cells that respond to oestrogen have oestrogen receptor
Oestrogen receptor is a TF, over half breast cancer over express this TF
What are induced pluripotent stem cells (iPS)
pluripotent stem cell generated directly from adult cell
How can iPS be generated
inserting 4 TFs into adult cell
What is encode
The ENCyclopaedia Of Dna Elements funded by national human genome research institute
what is the aim of encode
Identify regions of transcription, TF association, chromatin structure and histone modification.
Proportions within noncoding DNA
20% functional 60% non-functional
What does functional non-coding DNA do
involved in regulation of the expression of coding genes - regulatoruy sites close and distant from gene
Number point mutations involved in human disease in non-coding
90%
places where regulation of gene expression can occur
transcription RNA processing RNA transport RNA turnover Translation protein activity
