1.07 - Gene Expression Flashcards
Define: Gene Expression
Gene expression is the process of synthesising a functional gene product (usually protein, can also be functional RNA), from genetic information (DNA)
Define: Gene regulation
Gene regulation is any one or combination of processes that leads to a change in the natural level of expression of a gene.
At what three main levels can a gene be regulated?
Transcription Regulation (promotor, transcription factors)
Post transcriptional regulation (isoforms, mRNA transport and stability, protein processing)
Epigenetic (DNA methylation, chromatin)
What four main ways can regulation of transcription occur?
Through:
Repressors (decrease gene signal)
Activators (make a gene become transcribed)
Enhancers (boost up a signal)
Silencers (completely stop a gene from being expressed)
What is the promotor region?
A promoter is a region of DNA that initiates transcription of a particular gene.
Promoters are located near the transcription start sites of genes, on the same strand and upstream on the DNA (towards the 5’ region of the sense strand)
What is a TATA Box?
A particular sequence recognised by generalised transcription factors that then bind to the TATA box
How do gene regulatory proteins have their effect?
Because of the tightly coiled nature of DNA, gene regulatory proteins cause the DNA to either become more tightly bound and act as repressors or silencers or alternatively, unwind the DNA and act as enhancers or activators.
What effect does phosphorylation have on a protein?
It induces a conformational change. Can either make the protein more or less active or even cause it to be degraded.
What key protein in transcription requires binding of general transcription factors (GTFs)
RNA Polymerase II. Factors include: TFIIA, TFIIB, TFIID etc.
Describe NF-kb
A protein complex that controls transcription.
Plays a role in regulating the immune response to infection, responsible for cytokine production and cell survival.
Can bind to promotor regions on a number of genes.
Explain the regulation pathway of NF-kb
Under normal conditions IkBa is inhibiting NF-kB. Activation of IKK phosporylates IkBa. This releases IkBa from NFkB (activating it). It is then able to bind to the particular target gene and promote production of a given protein
What effect does NF-kb have on apoptosis and how does regulation of NF-kb change the survivability of the cell.
NF-kb inhibits programmed cell death (apoptosis). Thus, an up regulation of NF-kb will lead to cell survival by inhibiting apoptosis and if this occurs in excess it may lead to cancer/inflammatory disease.
Alternatively, a down regulation of NF-kb leads to apoptosis, and again, if done in excess may lead to developmental disorders
Describe alternative splicing
Alternative splicing is a regulated process during gene expression that results in a single gene coding multiple proteins. The pre-mRNA is spliced into multiple different iso forms leading to the creation of different proteins with different biological functions.
Alternate or abnormal variations in splicing are implicated in disease.
What is PCR and what are the major steps involved.
PCR is a technique used to amplify a specific segment of DNA.
Denaturation of the DNA (using high heat) splits the two stands apart.
Annealing of the primers to each of the DNA strands.
Extension is performed by DNA polymerase, it moves along the strand and attaches nucleosides in the buffer solution.
How is qPCR different from standard PCR
qPCR uses a fluorescent reporter that detects increases in DNA product and will fluoresce when bound to target DNA. Allows you to perform quantitative analysis on the sampled.
