Question

transcription and translation reinforcement

1. use the codon chart to write the amino acid that corresponds to each codon found in mrna:

agg ____ agu ____
cag ____ uac ____
gca ____ cgu ____
uuu ____ cca ____

1. write the codon that corresponds with each amino acid. there may be more than one.

arginine ____ glycine ____
valine ____ phenylalanine ____
histidine ____ threonine ____

1. a single codon is used to signal the beginning of protein synthesis. it is commonly called the start codon. locate the start codon on your codon chart.

what are the three bases of this codon? ______
what is the amino acid associated with these letters? ______

1. there are three codons that signal the end of synthesis, these are called stop codons.

what are the three stop codons? ______

1. for each sequence of dna shown below, write the complementary rna sequence. then use the codon chart to determine the amino acid sequence. be sure to begin at the start codon and end at the stop codon.

dna: g a c t a c g g a a g t a c t g c
rna :
amino acids :
dna: t t a c a t g g t c t a g a t t
rna :
amino acids:
dna: a c a t a c c a g a c c a t c t t
rna :
amino acids :

Explanation:

Step1: Match mRNA to amino acids

Using standard codon chart:

• AGG: Arginine
• CAG: Glutamine
• GCA: Alanine
• UUU: Phenylalanine
• AGU: Serine
• UAC: Tyrosine
• CGU: Arginine
• CCA: Proline

Step2: List codons for amino acids

Using standard codon chart (common options):

• arginine: CGU, CGC, CGA, CGG, AGA, AGG
• valine: GUU, GUC, GUA, GUG
• histidine: CAU, CAC
• glycine: GGU, GGC, GGA, GGG
• phenylalanine: UUU, UUC
• threonine: ACU, ACC, ACA, ACG

Step3: Identify start codon

Locate standard start codon:

• Bases: AUG
• Amino acid: Methionine (Met)

Step4: Identify stop codons

List standard stop codons:
UAA, UAG, UGA

Step5: Transcribe DNA to mRNA (1st sequence)

Complementary base pairing (T→A, A→U, C→G, G→C):
DNA: G A C T A C G G A A G T A C T G C
RNA: C U G A U G C C U U C A U G A C G

Step6: Translate 1st mRNA to amino acids

Start at AUG, stop at UGA (stop codon):
Amino Acids: Methionine (Met) - Proline (Pro) - Serine (Ser)

Step7: Transcribe DNA to mRNA (2nd sequence)

Complementary base pairing:
DNA: T T A C A T G G T C T A G A T T
RNA: A A U G U A C C A G A U C U A A

Step8: Translate 2nd mRNA to amino acids

Start at AUG, stop at UAA (stop codon):
Amino Acids: Methionine (Met) - Tyrosine (Tyr) - Proline (Pro) - Aspartic Acid (Asp)

Step9: Transcribe DNA to mRNA (3rd sequence)

Complementary base pairing:
DNA: A C A T A C C A G A C C A T C T T
RNA: U G U A U G G U C U G G U A G A A

Step10: Translate 3rd mRNA to amino acids

Start at AUG, stop at UAG (stop codon):
Amino Acids: Methionine (Met) - Valine (Val) - Tryptophan (Trp)

Answer:

1.

• AGG: Arginine
• CAG: Glutamine
• GCA: Alanine
• UUU: Phenylalanine
• AGU: Serine
• UAC: Tyrosine
• CGU: Arginine
• CCA: Proline

2.

• arginine: CGU, CGC, CGA, CGG, AGA, AGG
• valine: GUU, GUC, GUA, GUG
• histidine: CAU, CAC
• glycine: GGU, GGC, GGA, GGG
• phenylalanine: UUU, UUC
• threonine: ACU, ACC, ACA, ACG

3.

• Three bases of start codon: AUG
• Amino acid: Methionine (Met)

4.

• Stop codons: UAA, UAG, UGA

5.
First sequence:

• RNA: C U G A U G C C U U C A U G A C G
• Amino Acids: Methionine - Proline - Serine

Second sequence:

• RNA: A A U G U A C C A G A U C U A A
• Amino Acids: Methionine - Tyrosine - Proline - Aspartic Acid

Third sequence:

• RNA: U G U A U G G U C U G G U A G A A
• Amino Acids: Methionine - Valine - Tryptophan