The following base sequence represents part of a larger DNA molecule that is going to be analysed for the presence of open reading frames.

Explain how this DNA can have six possible reading frames.

State the type of codon that helps to identify open reading frames.

Once an open reading frame is identified, explain the steps researchers would follow to determine a potential function for that sequence.

a. «three» reading frames can occur in either strand 

b. from 5' « to 3' » 

c. reading frame can start from any of the first three nucleotides 

d. from the top strand: GTG or TGA or GAA as first triplet  OWTTE
OR
from the bottom strand: ATA or TAT or ATT as first triplet

start codon/AUG
OR
stop codon/UAA/UAG/UGA

a. use a database 

b. conduct BLAST search
OR
BLASTn allows DNA sequence alignment 

c. «sequence alignment software used» to identify/compare similar sequences in different organisms 

d. gene function can be studied using model organisms with similar sequences with known function OWTTE

e. BLASTp allows protein alignment
OR
EST may be used to identify gene activity 

f. can change sequence and create “knockout” study organism 

g. changes in phenotype due to knockout procedure allow determination of function 

h. valid example provided