Date | May 2018 | Marks available | 2 | Reference code | 18M.2.HL.TZ1.4 |
Level | Higher level | Paper | Paper 2 | Time zone | Time zone 1 |
Command term | List | Question number | 4 | Adapted from | N/A |
Question
Sickle cell anemia is due to a single base substitution in DNA. Using the diagram, outline how this translates into the production of an abnormal hemoglobin molecule by completing the spaces labelled I, II and III.
DNA codes for the amino acid sequence of polypeptides. List two other functions of DNA.
Distinguish between the purpose of free and bound ribosomes.
Markscheme
a. I: GUG
AND
II: CAC
b. III: Val/valine
Both required. Do not accept GAG to GTC.
a. promotion/repression/regulation of gene expression
b. introns (have functions in regulation of gene expression)
c. telomeres (form caps at the end of chromosomes)
d. coding for tRNAs/rRNAs
e. allows genes/traits/heritable characteristics to be passed to offspring
free ribosomes produce proteins for use inside the cell/cytoplasm whereas bound ribosomes produce proteins for secretion/for use outside the cell/for use in lysosomes