Gentics - Part B Flashcards
Where does transcription occur?
Within the nucleus.
Where does transclation occur?
In the cytoplasm.
Characteristics of DNA.
Double stranding, deoxyribose backbone, T as one of its bases, carries gentic code, within the nucleus.
What are characteristics of RNA?
Single stranded, Uracil subs for Thymine, ends in ribose, function is to copy DNA.
what are the different types of RNA
Messanger RNA - template for translation
Transfer RNA - involved in translation of mRNA
Ribosomal RNA - involved in translation of mRNA
What happens in initiation(transcription)?
RNA polymerase bond to TATA box in the promoter region. this opens a section of the double helix.
What is the TATA box?
a DNA sequence that indicates where a genetic sequence can be read and decoded
What happens in elongation(transcription)?
RNA polymerase to complementary NTPs on the template strand, RNA is stable so it falls of and the DNA reanneals
What happens in termination(transcription)?
Specific nucleotides in the DNA sequence are termination signals, meaning when the RNA polyamerase reaches them it detaches from the DNAstrand. The mRNA r4eleases and the DNA strand reforms unchange.
Elongation(translation)
Ribosomes and tRNA molecules add amino acids to protein strand.
Termination(translation)
Occures when one of the three stop condons is reached resulting in the release of the translation complex
Initiation (translation)
the mRNA gets fed into the ribosomes and first tRNA attaches to the start condon(AUG)
What happens to mRNA before it leaves the nucleus?
A 5’ cap is added, a3’ poly-A tail is added, splices out intron sequence
What is an intron?
Sequence of DNA that is not involved in coding for a protein.
what is a exon?
expressed sequence of DNA that codes for a protein.
why does the wobble hypothesis not cause mistakes?
Because the flexibility makes the amino acid the just the nucleotides are different
what happens when Poly-A Tail is not added?
Less mRNA would be exported from the nucleus.
What happens if exons are excised?
there could be altered protein sequence or loss of protein function.
what happens if 5’ cap isnt added?
mRNA wouldnt be recognised by the ribosomes in the cytoplasm.
how to mutations arise?
Errors are typically the cause of mutations.
what are point mutations?
Gene mutations that involve changes in one or a few nucleotides.
Type of point mutations.
substitution, insertion(a 3 pair is inserted somewhere), deletion
What is the difference between point mutations and frameshift mutations?
point mutations do not affect the neighbouring nucleotides where frameshift affects the entire chain after the point of mutatioln
