Flashcards in Topic 4c - DNA replication, transcription & translation Deck (12):
How many H bonds between T & A?
How many H bonds between G & C?
Where does bonding of nucleotides occur?
between the 3rd carbon of the sugar molecule of the upper nucleotide and the phosphate of the lower nucleotide
Human chromosomes range in length from ? to ?...?
from 23 million to 246 million bases
How fast is eukaryotic DNA replicated?
50 bases per second
T or F - DNA molecules are replicated in small chunks simultaneously
true - use replication bubbles
Transcription occurs where & produces what?
Nucleus & produces mRNA
Translation occurs where and produces what?
cytoplasm & produces proteins from amino acids from nucleotide sequences in mRNA
Stages of transcription...
1. Initiation - RNA polymerase binds to promoter region of DNA separating double helix near promoter
2. Elongation - RNA polymerase travels along DNA template strand synthesising RNA by catalysing addition of ribose nucleotides into RNA molecule.
3. Termination - end of gene, RNA polymerase encounters termination signal (DNA sequence) -> RNA polymerase detaches from DNA & releases RNA molecule
4. Conclusion of transcription - DNA rewinds into double helix. RNA -> cytoplasm for translation. RNA moves to another gene for transcription once again
T or F - in prokaryotes there is simultaneous transcription & translation
Stages of translation...
1. Initiation - tRNA + met bound to small ribosome subunit (preinitiation complex); then the complex binds to mRNA (tRNA anticodon pairs with AUG); then large subunit binds to small subunit & met tRNA binds to P site on large subunit
2. Elongation - second tRNA pairs with next codon at A site on large subunit; catalytic site catalyses peptide bond formation between 2 amino acids now at the A site; then the empty tRNA fucks off while the tRNA with the 2 AA's moves to the P site and leaves the A site vacant.
3. Termination - This is repeated until a stop codon is encountered, then mRNA & peptide are released from ribosome & subunits separate.