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1. The DNA sequence above has been re-written in Table 2 below. Transcribe and t

ID: 73803 • Letter: 1

Question

1.      The DNA sequence above has been re-written in Table 2 below. Transcribe and translate the DNA sequence, recording your answers in the boxes below. Look for punctuation codons (start and stop) because it signals the ribosome when to start and when to stop.

Table 2: Normal DNA: Transcribe and translate the amino acid sequence. Pay attention to punctuation codons. Type your answers in all capital letters.

Code word

1

2

3

4

5

6

7

DNA

G A G

T G G

T A C

A T G

T C A

A G C

A C T

mRNA

Amino acids

What would happen to the protein if 3rd base code word 4 in the DNA sequence above were changed from a “G” to a “C” as in the example below?

Table 3: Mutated DNA: Transcribe and translate the amino acid sequence. Pay attention to punctuation codons. Type your answers in all capital letters.

Code word

1

2

3

4

(mutation)

5

6

7

DNA

G A G

T G G

T A C

A T C

T C A

A G C

A C T

mRNA

Amino acids

B. Consider the following hypothetical gene. Indicate the sequence of the bases in the mRNA produced during transcription, and the sequence of the amino acids in the polypeptide produced during translation.

Table 4: Effect of Mutation: Original Sequence

Code word

1

2

3

4

5

6

7

DNA

T A C

G G C

A G T

C C T

T C T

G C A

A C T

mRNA

Amino acids

Table 5: Effects of Mutation: Base Substitution

Code word

1

2

3

4

5

6

7

DNA

TAC

TGC

AGT

CCT

TCT

GCA

ACT

mRNA

Amino acids

Table 6: Effects of Mutation: Base Addition

Code word

1

2

3

4

5

6

7

DNA

TAC

GGC

CAG

TCC

TTC

TGC

AAC

T

mRNA

Amino acids

Table 7: Effects of Mutation: Base Deletion

Code word

1

2

3

4

5

6

7

DNA

TAC

GCA

GTC

CTT

CTG

CAA

CT

mRNA

Amino acids

Code word

1

2

3

4

5

6

7

DNA

G A G

T G G

T A C

A T G

T C A

A G C

A C T

mRNA

Amino acids

Explanation / Answer

Code word

1

2

3

4

5

6

7

DNA

GAG

TGG

TAC

ATG

TCA

AGC

ACT

mRNA

CUC

ACC

AUG

UAC

AGU

UCG

UGA

Amino acids

Leucine

Threonine

Methionine

Tyrosine

Serine

Serine

Stop codon

The amino acid sequence is Leucine- Threonine- Methionine- Tyrosine- Serine- Serine

Table 3:

Code word

1

2

3

4

5

6

7

DNA

GAG

TGG

TAC

ATC

TCA

AGC

ACT

mRNA

CUC

ACC

AUG

UAG

AGU

UCG

UGA

Amino acids

Leucine

Threonine

Methionine

Stop codon

Serine

Serine

Stop codon

The mutated DNA will give rise to the amino acid sequence as Leucine- Threonine- Methionine

B. Table 4: Effects of mutation: original sequence

Code word

1

2

3

4

5

6

7

DNA

TAC

GGC

AGT

CCT

TCT

GCA

ACT

mRNA

AUG

CCG

UCA

GGA

AGA

CGU

UGA

Amino acids

Methionine

Proline

Serine

Glycine

Arginine

Arginine

Stop codon

Translated amino acid sequence is Methionine-proline-serine-glycine-arginine-arginine

Table 5: Effects of mutation: Base substitution

Code word

1

2

3

4

5

6

7

DNA

TAC

TGC

AGT

CCT

TCT

GCA

ACT

mRNA

AUG

ACG

UCA

GGA

AGA

CGU

UGA

Amino acids

Methionine

Threonine

Serine

Glycine

Arginine

Arginine

Stop codon

Translated amino acid after base substitution is methionine-threonine-serine-glycine-arginine-arginine

Table 6: Effects of mutation: Base addition

Code word

1

2

3

4

5

6

7

DNA

TAC

GGC

CAG

TCC

TTC

TGC

AAC

T

mRNA

AUG

CCG

GUC

AGG

AAG

ACG

UUG

A

Amino acids

Methionine

Proline

Valine

Arginine

Lysine

Threonine

Leucine

Translated amino acid sequence after base addition is Methionine-proline-valine-arginine-lysine-threonine-leucine

Table 7: Effects of mutation: Base deletion

Code word

1

2

3

4

5

6

7

DNA

TAC

GCA

GTC

CTT

CTG

CAA

CT

mRNA

AUG

CGU

CAG

GUU

GAC

GUU

GA

Amino acids

Methionine

Arginine

Glutamine

Valine

Aspartic acid

Valine

Asp or Glu

Translated amino acid sequence after base deletion is Methionine-arginine-glutamine-valine-aspartic acid-valine-Asp or Glu

Code word

1

2

3

4

5

6

7

DNA

GAG

TGG

TAC

ATG

TCA

AGC

ACT

mRNA

CUC

ACC

AUG

UAC

AGU

UCG

UGA

Amino acids

Leucine

Threonine

Methionine

Tyrosine

Serine

Serine

Stop codon