Edexcel IGCSE Biology 3.17B Protein synthesis
Practise converting DNA sequences into mRNA and comparing DNA with RNA, especially strand structure, bases and uracil use.
- Syllabus
- First assessment 2019
- Course
- Biology 4BI1
Exam points
- write complementary mRNA sequences from DNA, using U instead of T in RNA
- distinguish DNA and RNA by strand number, helix structure, sugar or base type
3.17B RNA structure question 1
[Maximum number: 2]
Apples contain an enzyme called phenol oxidase.
When apple tissue is exposed to oxygen in the air, this enzyme turns the apple tissue brown.
A genetically modified (GM) variety of apple has been produced that does not turn brown when exposed to air.
These apples have a gene in their DNA that produces a section of mRNA with a complementary sequence to the mRNA for the phenol oxidase gene.
State two differences between DNA and mRNA.
1
2
An answer that makes reference to three of the following points:
1. DNA is double stranded / RNA is single stranded
2. DNA has T / RNA has U
3. DNA is a helix / RNA is not a helix
4. DNA has deoxyribose / RNA has ribose
Accept DNA is
a double helix
= mp1 and
mp3
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