Questions and Answers
What direction is transcription carried out in?
5'->3'
Distinguish between the sense and antisense strands of DNA.
The antisense strand is the template DNA strand which is transcribed, while the sense strand has the same base sequence as the mRNA with thymine instead of uracil.
Explain transcription.
Transcription goes from DNA to mRNA, involving RNA polymerase binding to the promoter, uncoiling DNA, using one strand as a template, adding nucleotides in a 5'→3' direction, and stopping at the terminator.
Eukaryotic RNA needs the removal of introns to form mature mRNA.
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Study Notes
Direction of Transcription
- Transcription occurs in the 5' to 3' direction.
Sense and Antisense Strands of DNA
- The antisense strand (non-coding strand) serves as the template for transcription.
- The sense strand (coding strand) has the same base sequence as the resulting mRNA, with thymine instead of uracil.
Process of Transcription
- Transcription involves converting DNA to mRNA, initiated by RNA polymerase binding to the promoter region, which precedes the gene.
- RNA polymerase unwinds DNA, breaking hydrogen bonds between complementary base pairs.
- The template strand used for transcription is the antisense strand.
- Free nucleoside triphosphates pair with complementary bases on the template strand to form mRNA.
- In RNA, uracil pairs with adenine instead of thymine.
- RNA polymerase creates covalent bonds between nucleotides and continues along the DNA until it reaches a terminator sequence, signaling the end of transcription.
- Upon reaching the terminator, RNA polymerase detaches, mRNA separates from the DNA, and the double helix re-forms.
Eukaryotic RNA Processing
- Eukaryotic RNA requires intron removal to produce mature mRNA.
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Test your knowledge of transcription with these flashcards. Cover topics including the direction of transcription and the difference between sense and antisense DNA strands. Ideal for HL biology students looking to reinforce their understanding of genetic transcription.
