DNA Electrophoresis

Data Sheet: Activity – DNA Electrophoresis

 

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Name	Course	Date

 

Activity Data Code      

 

Procedure I – DNA Fragment Size

 

In the table below indicate which sample contains the smallest DNA fragment and which sample contains the largest DNA fragment. Note: Sample 1 is in Lane 1 of the gel, etc.

 

Lane 1 Fragment	Lane 2 Fragment	Lane 3 Fragment	Lane 4 Fragment	Lane 5 Fragment

 

 

Observations and Questions

 

[1] What is the composition of a DNA fragment? That is, what is a DNA fragment made of?

 

 

 

 

 

 

 

[2] Using the lane numbers on the electrophoresis instrument, list the samples from smallest DNA fragment to largest DNA fragment. Label the largest and smallest.

 

 

 

 

 

 

[3] What accounts for the different final locations of the different size DNA fragments? That is, why do different sized DNA fragments end at different locations on the electrophoresis instrument?

 

 

 

 

 

 

Procedure II – Crime Scene DNA

 

In the table below indicate the number of DNA fragments each sample has in common with the crime scene sample (Lane 2). Note: Sample 1 is in Lane 1 of the gel, etc.

 

Tip: It is helpful to use a ruler when attempting to match up DNA fragments in the gel. A bank/ATM/credit card works well too.

 

 

Lane 1 Student	Lane 2 Crime Scene	Lane 3 Suspect	Lane 4 Suspect	Lane 5 Suspect
	6

 

 

Observations and Questions

 

[4] Does the crime scene sample contain bands in common with the student? Explain why or why not.

 

 

 

 

 

 

 

[5] Which suspect (if any) CANNOT be excluded from suspicion? Explain your answer.

 

 

 

 

 

 

 

 

Procedure III – Paternity Case

 

In the table below indicate the number of DNA fragments each sample has in common with the child/calf sample (Lane 2). Note: Sample 1 is in Lane 1 of the gel, etc.

 

Tip: It is helpful to use a ruler when attempting to match up DNA fragments in the gel. A bank/ATM/credit card works well too.

 

Lane 1 Mother	Lane 2 Calf	Lane 3 Male	Lane 4 Male	Lane 5 Male
	6

 

 

Observations and Questions

 

[7] Which sample is from the father of the calf? Explain your answer.

 

 

 

 

 

 

[8] How many bands does the calf have in common with its mother? How many bands does the calf have in common with its father? Propose a plausible explanation for the number of bands from each parent.

 

 

 

 

 

 

 

 

[9] After adding the probe and filter, what additional information have you learned about the genotype of the calf?

 

 

 

 

 

 

 

[10] Given that the probe pairs with a specific DNA strand in the matrix, what can you conclude about the nucleotide sequence of the Baby’s DNA fragment that pairs with the probe sequence?

 

 

 

 

 

 

[11] Discuss reasons that it might be useful to find out whether a newborn carries a specific gene or allele.

 

 

 

 

 

 

 

 

Procedure IV – Species DNA Comparison

 

 

Observations and Questions

 

[12] In your own words, explain why it is necessary to include only one chain-terminating/synthesis-terminating nucleotide in each well of the electrophoresis instrument.

 

 

 

 

 

 

 

 

[13] Determine the DNA sequence by analyzing the location of each nucleotide across the four lanes of the electrophoresis instrument. Provide the DNA sequence as your answer here.

 

Important: remember that your sequence starts from the shortest fragment!

 

 

 

 

 

 

 

 

 

[14] What is the significance of finding that DNA sequences are highly similar for two different species?

 

 

 

 

 

 

[15] Below, align the newly determined DNA sequence with the sequences of the three known plant species (see data under the Activity Form tab). Next, compute the percent alignment of the bases for the three comparisons.

 

Show the alignment and percent alignment calculation for Plant 1. Highlight the Plant 1 differences in yellow.

 

 

 

 

 

Show the alignment and percent alignment calculation for Plant 2. Highlight the Plant 2 differences in yellow.

 

 

 

 

 

Show the alignment and percent alignment calculation for Plant 3. Highlight the Plant 3 differences in yellow.

 

 

 

 

 

Which known species has a genotype that is most similar to that of the unknown plant?

 

 

 

[16] A biologist at World University used Procedure IV to conduct an additional study and found the sequence following below. Using your knowledge of central dogma generate the amino acid sequence that results from this sequence.

 

Given DNA sequence: CAC GAC GGA TTC GTA