BIO3: Control of Gene Expression: Biotechnology Flashcards
polycistronic
Polycistronic mRNA can encode more than one polypeptide separately within the same RNA molecule (e.g. bacteria)
Describe monocistronic
Monocistronic mRNA (primarily in eukaryotes) contain the coding sequence only for one polypeptide
How do prokaryotes control gene expression?
Operons that result in multiple genes per mRNA (polycistronic mRNA) only exist in prokaryotes
operons
Operons are a group of genes controled by a single promoter (all or nothing expression)
How do eukaryotes control gene expression?
- Transcription regulation
- Changes in gene number
- Translation regulation
- Failure to control
- DNA and chromatin structural modifications
operator
Operators are regions of DNA which enables the regulation of genes on the operon
What type of proteins bind regulate transcriptional activity in prokaryotes?
Activator and repressor proteins (decrease rate of transcription)
Describe the lac operon
Lac operon plays a catabolic role where transcription of lac is induced by the presence of lac (the substrate) that the operon’s enzymes break down
Describe the trp operon
Trp operon play an anabolic role where transcription of trp is represssed by the presence of trp (the product) of the operon’s enzymes
What are the components of the Lac Operon?
- Promoter region (P region) - RNA pol binds to begin transcription
- Operator region (O region) - repressor binds to decrease transcription
- Structural genes - lac Z, lac Y, lac A
How is gene expression controlled in bacteria?
In prokaryotes, gene regulation occurs at the transcription level (since transcription and translation occur simultaneously); the stronger the affinity between RNA pol and the promoter, the higher the transcription rate
Where does regulation of gene expression occur in bacteria?
Repressor proteins bind to the operator region of DNA; activator proteins bind to the enhancer region of DNA
transcription factor (TF)
TFs are proteins that control the rate of transcription by activating/repressing the activity of RNA Pol and modulate the interaction of RNA Pol and the promoter
RNA processing
The addition of a 5’ cap and 3’ poly-A tail that increases the stability of RNA, making it last longer in the cytosol
How many times can RNA be translated?
mRNA can continuous be read to make proteins
RNA interference
RNA molecules reduce translation by degrading some specific mRNA molecules
What types of RNA are involved in RNA interference?
- miRNA
2. siRNA
miRNA
miRNA are single stranded RNA molecules that are complementary to the mRNA molecule, bind to it, and degrade it
siRNA
siRNA are double stranded RNA that forms a complex with a protein, binds to a specific mRNA molecule, cleiving it
gene amplification
Gene amplification (or gene duplication) is the duplication of a region of DNA resulting in an increase in the number of copies of a gene
anueploidy
Having an abnormal # of chromosomes (an entire chromosome has been duplicated or lost)
angiogenesis
Development of new blood vessels
Describe the cancer growth process
Normal cells undergo apoptosis when DNA mutations occur but cancer cells avoid apoptosis. Cancer cells undergo angiogenesis which fuels tumor groups. Cancerous tissue invades and damages surrounding organs
oncogenes
Genes that regulate cell growth, differentiation, and the process of apoptosis and can potentially cause cells to become cancerous
proto-oncogenes
Normal genes involved in cell growth that get mutated
tumor suppressor genes
Genes that have the potential to prevent cancer (trigger apoptosis, DNA repair, or decrease cell division)
epigenetics
Changes in gene expression not due to change in DNA sequence (e.g. chromatin remodeling)
chromatin remodeling
Changing arrangement of chromatin between heterochromatin/euchromatin that leads to changes in gene expression
What types of covalent modifications occur to histone proteins in chromatin remodeling?
- Acetylation/deacetylation
- Methylation/demethylation
- Phosphorylation
rDNA
Recombinant DNA are DNA molecules made from combining DNA from 2 or more different sources
restriction enzymes
endonucleases that recognize and cleave specific DNA sequences (producing “sticky ends” and rDNA when annealed)
endonuclease
enzyme that cleaves a nucleotide chain in the middle of the chain
exonuclease
enzyme that cleaves a nuscleoide from the end of a chain
phosphodiester bonds
joins nucleotides
FISH
Flourescent in situ hybridization - used to determine gene expression in a specific tissue
What questions does FISH address?
Is a certain gene expressed? If so, how much and in what region of tissue?
PCR
Polymerase chain reaction - used to amplify DNA to determine quantity of DNA present
Describe the PCR process
Repeated cycles of heating and cooling (denature and anneal) and DNA extension
Gel eletrophoresis
Used to separate macromoles of DNA and proteins by size and charge
Describe the gel eletrophoresis process
Sample is placed at - (cathode) end of gel and electrical field is applied so negatively charged molecules migrate towards + (anode) opposite end of gel
SDS-PAGE
Separate denatured proteins by their molecular weight
Native-PAGE
Proteins separated by size in their native conformation
Southern blot
Detect a certain fragment of DNA from a sample
Northern blot
Detect a certain fragment of RNA from a sample
Western blot
Detect a specific protein from sample
Sanger sequencing
Method of DNA sequencing using ddNTP to terminate nucleotide chain elongation and generate various fragments to map to
