REPLICATION, TRANSCRIPTION & TRANSLATION QUESTIONS

1. Identify the 4 bases shown below – which are Purines? Which are Pyrimidines?

2. Which ones join together to form base pairs in the DNA molecule?

3. Why is DNA replication known as semi-conservative?

4. For each DNA strand – write the complementary strand. Be sure to include the 5’ and 3’ ends

a. 5’ - C A G T G G A C C T C A C T T A G A T T G G A – 3’

b. 3’- T TT A G A C T A G G A A C C T A A G A G -5’

c. 5’ - G A T T A C A G A T T C A G A T T A C A G A T A G G A A C C T C T C A C T T A – 3’

5. For this strand below – write the complementary strand and then replicate this DNA helix through one round of replication. Write out the resulting DNA helices.

5’ - G A T T A C A G A T T C A G A T T A C A G A T A G G A A C C T C T C A C T T A – 3’

COMPLEMENTARY STRAND

Replicate both of these strands

6. In terms of DNA replication, what are the roles of:

a. DNA polymerase III -

b. DNA polymerase II –

c. DNA polymerase I -

d. Helicase –

e. Primase –

f. DNA ligase –

7. What is the purpose of a proof-reading enzyme in DNA replication? What DNA polymerases are capable of proof reading?

8. What are the three differences between RNA and DNA?

9. Where is DNA found in the cell? ______

Where is RNA found in the cell (2 places)? ______

10. Fill in the below table:

Type of RNA / Function / Basic drawing
mRNA
rRNA
tRNA

11. What is transcription?

12. What strand is the template strand used for transcription?

14. Below is a drawing of a cell. Show where transcription and translation occur. Identify the locations of the DNA and the RNA (all three types!) plus the fully assembled ribosomes:

15. What is the function of:

a. mRNA –

b. RNA polymerase II –

c. tRNA–

d.the codon –

e. the anti-codon site –

16. What three modifications are necessary to convert an RNA transcript into mRNA?

17. Using the following sense strand – what would be the eventual sequence of the RNA strand produced following transcription (don’t worry about finding a start and stop codon)?

5’ - G A T T A C A G A T T C A G A T T A C A G A T A G G A A C C T C T C A C T T A – 3’

mRNA:

a. Where would you put the cap and the tail on this RNA transcript?

b. Write the mRNA so that the codons are obvious

c. Write the anti-codon sequence

d. Write the amino acid sequence

18. What are the three stop codons?

19. What codons code for serine?

20.How many codons are there for valine? for asparagine? for tryptophan?

21. These six possible codons for arginine might appear in a molecule of mRNA. For each one, write the anticodon on the tRNA molecule that will carry arginine to the ribosome when that particular codon is read.

Codon / Anticodon
C G U
C G C
C G A
C G G
A G A
A G G

22. For the DNA sequences given below, write the correct mRNA sequence that would result following transcription. Where would you modify the mRNA with a methylated cap and a poly-A tail?What are the polypeptide strands that would result following translation? Underline the untranslated regions (if present). BE CAREFUL! You may have to replicate this DNA strand before you transcribe!

a. DNA5’ A T C A T G C G A G GG C T T A AAA C C G A C A T T A G C C T G A T TT A G GG C 3’

HINT: the mRNAsequenceis the same as the senseDNAstrand – EXCEPT the nucleotide T isnow a U

mRNA

  1. DNA5’ CCC G A G A T G GG A T TT C T C G G A AAA T T C A G G T A AA C A T G C 3’

mRNA

23. For each of the following sequences, complete the series by filling in the missing DNA, mRNA sequence, codon triplet, tRNA anticodons, & the amino acid sequences (don’t worry about finding a start codon). If several amino acid sequences might work choose any one. Stop translating once you find a stop codon.

A. DNA: A T A C G A AA T C G C G A T C G C G G C G A T T C G G

mRNA:

Codon:

Anti-codon:

AminoAcids:

B. DNA: T TT A C G G C C A T C A G G C A A T A C T G G

mRNA:

Codon:

Anti-codon:

AminoAcids:

C. DNA: T A C G GG C C T A T A C G C T A C T A C T C A T G G A T C G G

mRNA:

Codon:

Anti-codon:

Amino Acids:

D. DNA: C G A T A C A A T G G A C CC G G T A T G C G A T A T C C

mRNA:

Codon:

Anti-codon:

AminoAcids:

E.DNA:

mRNA: A U G A C U A G C U G GGGG U A U U A C U UUU A G A A

Codon:

Anti-codon:

Amino Acids:

F. DNA – sensestrand: T A C A T G C G C T C C G C C G T C G A C A A T A C C A C T

DNA – anti-sensestrand:

mRNA:

Codon:

Anti-codon:

Amino Acids:

G.DNA:

mRNA: A U G A C U A G C U G GGGG U A U U A C U UUU A G

Codon:

Anti-codon:

Amino Acids:

H.DNA:

mRNA:

codon: UAC CAC CCC CGU AUG GCU GGG AAU UAA

amino acids:

I.DNA:

mRNA:

codon: UAC CAC CCC CGU AUG GCU GGG AAU AUC

amino acids:

J.DNA:

mRNA:

codon:

AA: MET ARG GLY PHE PHE MET VAL GLY

24. For each of the following sense or anti-sense DNA sequences, complete the series by filling in the missing DNA, mRNA sequence, codon triplet, tRNA anticodons, & the amino acid sequences using the correct reading frame. If several amino acid sequences might work choose any one.

SenseDNA: A T A A T G C G A AA T C G C G A T C G C G G C G A T T C G G A A T A G

mRNA:

Codon:

Anti-codon:

AminoAcids:

Anti-senseDNA: C G A T A C A AA T G T G G A C CC G G T A T G C G A T A T G A T C C T G

mRNA:

Codon:

Anti-codon:

Amino Acids:

Anti-senseDNA: T A C C G A T G GGG C T C C G C C G T C G A T A C C A A T A C C A C T

mRNA:

Codon:

Anti-codon:

AminoAcids:

Fill in the following flowchart