RNA synthesis Flashcards
what is the main function of transcription?
for mRNA to be synthesised in the nucleus
Does the language remain the same?
As the transcript goes from DNA to mRNA so contains the same language
what is the main function of translation?
proteins are produced from mRNA
Does the language remain the same?
Transcript of the mRNA produces the protein so therefore they contain different languages
how many nucleotides are in the human genome?
3.2x10^9
What are the two homologs found in chromosomes?
paternal and maternal
what is the key function of chromosomes and what do they contain?
22 pairs of autosomes and 1 pair of sex chromosomes
centromere and telomere
pseudo genes
centromere
is made up of DNA and key function is to keep the chromosome attached to the spindle fibre during mitosis
telomere
located at end of chromosome
double stranded and a 6 pair repeat
protects end of chromosome by preventing fusion from neighbouring chromosomes
what is the intergenic region?
region of DNA between genes which have no current function
what is a gene and its properties?
unit of heredity - contains instructions for an organisms phenotype
DNA segment containing the formation of a particular product
differ in size
differ in number of introns and exons
cluster into families
what is the promoter?
region/ DNA sequence to which RNA polymerase binds to the initiate transcription
cis acting element (only works on promoter region)
what is the TATA box?
consists of 6 nucleotides; TATAAT
appears at -10 to -25 (upstream)
found in genes that are actviely transcribed by RNA
What is TTAGACA?
-35 sequence
sequence recognised by delta factor
promoter region
What does DNA transcribe into and what does RNA polymerase catalyse?
DNA transcribes into RNA and it catalyses the formation of phosphodiester bonds
types of RNA polymerase
RNA polymerase I - most ribosomal RNA
RNA polymerase II - protein coding, microRNA, non coding RNA
RNA polymerase III - tRNA, 5S rRNA, other small RNAs
how many bases are transcribed roughly during RNA synthesis?
about 1.25-1.75kb per min so quite fast
how do polymerases work during RNA synthesis as well as their effect on the number of transripts from a gene simultaneously?
many polymerases work on the same gene
many transcripts from a gene simultaneously
Why are transcription factors required and what does the promoter contain which RNA polymerase II bind to (how many bps are there)?
requierd to initiate or regulate transcription and contains TATA box (30 bps)
transcription (initiation)
TATA box is recognized by the TATA binding protein (TBP), sub unit of transcription factor (TFIID) and binds distorting the DNA
This allows the binding of transcription factors, TFIIA (stabilizes the complex) and TFIIB (responsible for linking RNA polymerase to the complex) TFIIF is already associated with the RNA polymerase when the RNA polymerase binds to the TBP-TFIIB-TFIID complex Then other transcription factors TFIIE and TFIIH bind RNA polymerase II assembles at promoter: transcription initiation complex is formed TFIIH breaks apart the double helix at the transcription starting point It also phosphorylates RNA polymerase II, so it can begin transcription
transcription (elongation)
RNA strand gets longer by the addition of nucleotides at the growing 3’ end
transcription (termination)
when a sequence of DNA, known as a terminator and located after the stop codon, is reached transcription ends
what are untranslated regions and what are they required for?
transcribed but not translated as they are required for regulation
what is the 5 primer UTR responsible for?
involved in the regulation of translation
