2D Flashcards
Gene expression
the process by which the information stored in a gene is used to synthesises a functional product(such as a protein or RNA)
Stages involved in gene expression
- transcription
2.RNA processing
3.Translation
Transcription
involves the copying of DNA into an mRNA strand
Stages of transcription
- initiation
2.elongation - Termination
Inititation of transcription
Transcriptuon factors binds to the promtor region to initiate transcription
RNA polymerase binds to the promotor regions which signals to the weak hydrogen bonds between the DNA to break. resulting in the bases of the DNA strand to be exposed
Elongation of transcription
RNA polyermase moves along the template strand of the DNA in a 3’ to 5’ direction,
AS it moves along template strand, the complementary RNA nucloeitdies to produce a preMRNA molecule.
Termination of transcription
RNA polymerasereaches the termnation sequence so signas the termnation of transcirption
This signals the pre mRNA
molecule to be released for
processing
DNA molecule winds up and
hydrogen bonds reform between the DNA
the strands
transcription factors
proteins that turn specific genes on or off by binding to nearby DNA.
Transcription ends when
RNA polyermase reaches the termination sequence
RNA polyermase catalyses transcription through
the joining of complementary RNA nucleotides
premRNA is complementary to
the DNA template strand
in pre mRNA, adeninien binds with
uracil not thymine
to produce RNA, DNA has
DNA has to unwind
How does the processing of premRNA into mRNA occur(RNA processing/post transicrption modificaton
- remove introns which are non coding regions
- splicing exons, which are coding regions
- adding a methyl cap to the 5’ end of the mRNA molecule, this allows the mRNA molecule to bind to ribosomes during translation
- Add a poly A tail to the 3’ end of the mRNA molecule
- mature mRNA molecule exits the nucleus to the ribosomes for translation.
Alternative splicing
involves splicing of a pre mRNA in differnet ways to result in a differnt protein produced
Translation
involves the reading of mRNA molecule to of a polypeptide chain of amino acids in the ribosomes
3 stages of translation
- Inititation
2.elongation
3.termination
Initiation of translation
the 5’ end of the mRNA molecule attaches to the ribosome.
the start codon(AUG) is read, than a tRNA molecule with a complementary anticodon(UAC) binds to the ribosomes to deliver the amino acid methionine
Elongation in translation
the next codon in read, and the complementary tRNA molecule delievers a specific amino acid to the ribosome
This amino acid will bind to the adjacent amino acid to form a peptide bond
This process continues and a growing polypeptide chain on amino acids is produced.
Termination in translation
Once the stop codon is read,, this signals to the end of translation
There is no tRNA molecule that corresponds with the STOP codon
Instead a release factor binds to release a polypeptide chain of amino acids for modification
template strand vs non template strand
the strand thatRNA polyermase uses to produce mRNA
strand that has the exact same sequence to the RNA.
where does transcription occur from
transcription occurs from the 5’ to 3’ end of the non template strand(top strand).
post transcription modification
process which covnerst the prerna molecule into an mRNA molecule is known as
pre RNA molecule is made up of
non coding regions-introns
coding regions-extrons
