I’m working on a biology exercise and need an explanation to help me learn.
Skill Check Worksheet NAME:_______________________
DNA: It’s All in Our Genes Lab Section: _________________
Pre-Lab: Read through the basic tutorial and then answer the following questions.
1.What does gel electrophoresis allow scientists to do with DNA?
2.In order to make the DNA move through the gel, what must be done to it?
3.What direction does the DNA move (+ to – or – to +)
Why do you think it moves in that direction?
4.Which DNA strands will move farthest (smaller or larger strands)? Explain why.
You will now virtually make and run your own gel. Please follow the 5 steps carefully and answer the corresponding questions.
Step 1: Make the gel
1. List the ingredients to make a gel:
2. What is agarose made from?
3.Why does buffer have to be added to make the gel?
Step 2: Set up gel apparatus
1. What do you need to set up the gel apparatus?
Step 3: Load DNA into gel
1. What solutions/items are needed to load DNA into the gel?
2. Why do you need to add loading buffer to the samples (Two reasons!)?
3. Why do you need to add a DNA standard to the gel? What will it be used for?
Step 4: Hook up electrical current to run gel
1. The black plug is (+ or -)?
The red plug is (+ or -)?
2. Once you turn on the power supply, how do you know the current is running?
Step 5: Stain gel and analyze results
1. What is the chemical used to stain the DNA in the gel?
2. How does this stain work?
3. Is this stain harmful to your DNA? Should gloves be worn when staining DNA?
4. What are the estimated sizes of the three DNA strands? What does bp stand for?
Activity 3: Analysis of Forensic Samples
This photo is an actual photo of a gel that was run using the samples outlined in this lab. From left to right:
Lane 1: A HindIII DNA digest used as the control for the size standards
Lane 2: Crime scene sample
Lane 3: Suspect 1: Dr .Pete Moss
Lane 4: Suspect 2: Dr. Forest Moss
Lane 5: Suspect 3: Mr. Bud Wieser
Lane 6: Blood sample from the victim, Dr. Dinah Soares
You will need to look at the bands on the gel very carefully, as some of the bands are quite faint. That does not make them any less important just because the bands may be faint.
In order to make sure that you do not miss any of the bands the first thing that you should do is make a drawing in the space below; draw the band pattern in each of the lanes. Be sure to label the lanes as to their contents, and then draw the bands in proportion to their positions on the gel. Be sure to account for faint bands.
Question 1: Do you see any of the band patterns in the different lanes that appear to match each other? Which lanes?
Question 2: Do any of the suspect samples appear to have recognition sites at the same location as the DNA from the crime scene?
Question 3: Based on the analyses you have done, do any of the suspect samples of DNA seem to be from the same individual as the DNA from the crime scene? Describe the scientific evidence that supports your conclusion.
Activity 4: Summary of Data Analysis
Write a summary of your evidence, and who (if anyone) it points to as the alleged murderer. Be sure to discuss your electrophoresis process, how you analyzed the data, and summarize your results and conclusions. Is this data sufficient to convict your suspect do you think? What other evidence do you think you should have to take this to court?