Date | November 2018 | Marks available | 1 | Reference code | 18N.3.SL.TZ0.10 |
Level | Standard level | Paper | Paper 3 | Time zone | TZ0 / no time zone |
Command term | Identify | Question number | 10 | Adapted from | N/A |
Question
A section of mRNA contains the start codon for translation of a polypeptide by the ribosomes.
Identify the nucleotides of the start codon for the polypeptide.
State the chemical difference between the 5' end and the 3' end of a DNA strand.
Within the base sequence shown in the diagram, the sequence for the stop codon UGA appears. Explain the reasons for translation continuing beyond this point in the mRNA.
Describe how bioinformatics can help identify genes within the DNA of an organism.
Markscheme
AUG ✔
5′ end contains a phosphate group «on carbon 5»
OR
3′ carbon contains a hydroxyl/OH group «on carbon 3» ✔
a. the gene code occurs in triplets ✔
b. the stop codon would not be part of the reading frame ✔
c. the code for a polypeptide would contain more codons ✔
a. bioinformatics is the application of computer technology to biological information
OR
information is stored in a database
OR
bioinformatics is used in analyzing genomes ✔
b. allows for searches/comparisons/analysis of ORF/open reading frame ✔
c. the computer searches for a start codon and a stop codon «and within a distance of 60+ codons» ✔