Blitvak Week 2
From LMU BioDB 2015
Contents
Individual Journal Assignment Week 2
Given Strand of DNA
5’-cgtatgctaataccatgttccgcgtataacccagccgccagttccgctggcggcatttta-3’
- Given strand is written from 5’ to 3’; each strand has a complementary antiparallel strand
- The given strand is the mRNA-like strand
Given Strand and the Complementary Strand
5’-cgtatgctaataccatgttccgcgtataacccagccgccagttccgctggcggcatttta-3’ - Given, mRNA-like strand 3’-gcatacgattatggtacaaggcgcatattgggtcggcggtcaaggcgaccgccgtaaaat-5’ - Found, template strand
- Since the given strand runs from 5’ to 3’, the complementary strand will run from 3’ to 5’
- Complementary strand was found by applying the base pairing of C-G, and A-T
- Under each base letter of the given strand, the corresponding base letter (that forms a base-pair) is written to find the complementary strand
- Since the given strand is 5’ to 3’, it is the strand that is the mRNA-like strand. This is due to the fact that DNA/mRNA must be synthesized from the 5’ to 3’ direction (via the template strand)
Reading Frames of the mRNA-like strand
+1 Reading Frame
Transcribed mRNA codons
5’-cgu aug cua aua cca ugu ucc gcg uau aac cca gcc gcc agu ucc gcu ggc ggc auu uua-3’
Translated Amino Acid Sequence
Nter-RMLIPCSAYNPAASSAGGIL-Cter
+2 Reading Frame
Transcribed mRNA codons
5’-c gua ugc uaa uac cau guu ccg cgu aua acc cag ccg cca guu ccg cug gcg gca uuu ua-3’
Translated Amino Acid Sequence
Nter-VC(STOP)YHVPRITQPPVPLAAF-Cter
+3 Reading Frame
Transcribed mRNA codons
5’-cg uau gcu aau acc aug uuc cgc gua uaa ccc agc cgc cag uuc cgc ugg cgg cau uuu a-3’
Translated Amino Acid Sequence
Nter-YANTMFRV(STOP)PSRQFRWRHF-Cter
- Convert the DNA strands to mRNA by applying A-U pairing rather than A-T pairing
- A reading frame is one of the ways of dividing a strand into triplets (or codons)
- Stop codons are designated by (STOP)
- There are three possible reading frames with the mRNA-like strand, the +1, +2, and +3
- +1 reading frame is from the first base to the last base in a given mRNA-like strand (the entire strand)
- +2 reading frame excludes the very first base from the reading frame
- +3 reading frame excludes the first two bases from the reading frame
- It is helpful to group the sequences into triplets and exclude incomplete triplets
- Use an RNA Codon Table to find the amino acids that correspond to the codons (triplets) in mRNA
- Different reading frames lead to different sequences of amino acids
- All reading frames are from 5’ to 3’
Reading Frames of the template strand
-1 Reading Frame
Transcribed mRNA codons
5’-uaa aau gcc gcc agc gga acu ggc ggc ugg guu aua cgc gga aca ugg uau uag cau acg-3’
Translated Amino Acid Sequence
Nter-(STOP)NAASGTGGWVIRGTWY(STOP)HT-Cter
-2 Reading Frame
Transcribed mRNA codons
5’-u aaa aug ccg cca gcg gaa cug gcg gcu ggg uua uac gcg gaa cau ggu auu agc aua cg-3’
Translated Amino Acid Sequence
Nter-KMPPAELAAGLYAEHGISI-Cter
-3 Reading Frame
Transcribed mRNA codons
5’-ua aaa ugc cgc cag cgg aac ugg cgg cug ggu uau acg cgg aac aug gua uua gca uac g-3’
Translated Amino Acid Sequence
Nter-KCRQRNWRLGYTRNMVLAY-Cter
- Finding reading frames is the same for the template strand as it is for the mRNA-like strand, but each is designated as -1, -2, and -3 respectively
- Since there are also 3 possible reading frames for the template strand, there are 6 total reading frames in double-stranded DNA
- Since the complementary template strand is 3’ to 5’, it must be reversed so that it is 5’ to 3’ (prior to finding its reading frames)
Open Reading Frames
- The +1, -2, and -3 reading frames are all open reading frames since they all contain no stop codons in their mRNA sequences
Brandon Litvak
BIOL 367, Fall 2015
| Weekly Assignments | Individual Journal Pages | Shared Journal Pages |
|---|---|---|
|
|
|
|
