Unit 1 KA3 - Gene expression Flashcards
what is transcription and what are it’s needs?
the synthesis of mRNA from a section of DNA.
template DNA gene, RNA nucleotides, ATP and RNA polymerase.
describe the first stage of transcription.
RNA polymerase unwinds the gene from its double helix and breaks the hydrogen bonds between the complementary base pairing.
describe the second stage of transcription.
RNA polymerase makes a complimentary copy of the template DNA strand by adding complementary RNA nucleotides.
describe the third stage of transcription.
sugar-phosphate backbone forms on messenger RNA strand.
the primary transcript is formed.
describe the fourth stage of transcription.
weak hydrogen bonds break between primary transcript and the template DNA.
describe RNA splicing.
the process where introns are removed from the primary transcript, forming a mature transcript.
this is the version of mRNA that leaves the nucleus and goes to the ribosome, where translation occurs.
what is translation and where does it take place?
when a complementary mRNA copy of a gene is made, takes place in the nucleus.
describe the first stage of translation.
the mRNA carries a copy of the genetic code to the ribosome.
describe the second stage of translation.
the ribosome must bind to the START codon of the mRNA strand before translation can begin.
describe the third stage of translation.
each tRNA molecule attaches to its specific amino acid and transports it to the ribosome.
describe the fourth stage of translation.
the anticodons of the tRNA pair up with the codon on the mRNA through complementary base pairing.
describe the fifth stage of translation.
the amino acids are lined up in a specific sequence determined by the genetic code.
describe the sixth stage of translation.
peptide bonds form between neighbouring acids.
describe the seventh stage of translation.
the amino acid separates from the tRNA molecule and the tRNA molecule leaves the ribosome and returns to the cytoplasm to pick up another amino acid.
describe the eighth stage of translation.
the process continues until the STOP codon is reached.
this releases the polypeptide from the ribosome.
this required ATP.
