Biology Honors
Link to blog- abaly2020.wixsite.com/biohonors
Forensic Lab One: Hair Analysis
Overview- Students took two hairs, ideally from two different places with at least one hair having the follicle(as the follicle is the only part of the hair that has specific DNA in it), and placed them on a slide to look at under a microscope in order to determine what hair truly looks like
After completing this lab we where able to see how each how hair was different from person to person in differences between individual's cuticle, cortex, and medulla. We could see differences in cuticle, the scaly outermost part of the hair, through how thick it was, the shape and area of cross sections, color variations/patterns, and the degree of curls and kinks in an individuals hair. We could also see differences in the cortex, the middle layer of of a hair, via how much melanin it contains (visible through the pigment). And finally, we could see differences in the Medulla, the innermost part of the hair, from its thickness or patterns.
How can hair be used as a source of individual and/or class evidence?-
Hair with a follicle can most definitely be used as a source of individual evidence as the follicle of a hair contains an individual's unique DNA- but hair with a follicle is not always easy to come by as the follicle could be washed away or separated from the hair upon being ripped out. Though hair without a follicle can provide class evidence through each strand of hair's cuticle, cortex, and medulla and can reveal an individuals diet, drug history, or (if the individual has bleached their hair) even lead back to the owner of the hair.
After completing this lab we where able to see how each how hair was different from person to person in differences between individual's cuticle, cortex, and medulla. We could see differences in cuticle, the scaly outermost part of the hair, through how thick it was, the shape and area of cross sections, color variations/patterns, and the degree of curls and kinks in an individuals hair. We could also see differences in the cortex, the middle layer of of a hair, via how much melanin it contains (visible through the pigment). And finally, we could see differences in the Medulla, the innermost part of the hair, from its thickness or patterns.
How can hair be used as a source of individual and/or class evidence?-
Hair with a follicle can most definitely be used as a source of individual evidence as the follicle of a hair contains an individual's unique DNA- but hair with a follicle is not always easy to come by as the follicle could be washed away or separated from the hair upon being ripped out. Though hair without a follicle can provide class evidence through each strand of hair's cuticle, cortex, and medulla and can reveal an individuals diet, drug history, or (if the individual has bleached their hair) even lead back to the owner of the hair.
Forensic Lab Two: "Who Stole Ross's Expo Marker?"
Overview- In this lab a "crime" had taken place in which someone took Ross's black expo marker and replaced it with a dried out yellow, the suspects of the crime where Jorge and Fran and we needed to see which which suspect was guilty by matching their DNA to the DNA found on the evidence we received.
What part of DNA is tested for DNA profiling?-
The amount of base pairs repeated is what is used to determine matching DNA as it is nearly impossible for two individuals to have a matching number of base pairs.
Why does the DNA of different people appear at different locations in the Electrophoresis gel?
Upon completing the lab technicalities we saw that each persons DNA had a different pattern and that one matched the pattern found on the expo marker. we know the DNA appeared in these different patterns because each person has a unique amount of base pairs that can be heavy or light depending on amount causing them to move at different paces.
What causes the DNA to move through the Electrophoresis gel
the DNA has a negative charge so the positive charge on the opposite side causes the DNA to move. The DNA had a pattern in the gel because the larger the amount of base pairs the heavier it is (meaning it stayed nearer to the negative charge) and the DNA with less base pairs had a pattern nearer to the positive charge as it was lighter to move.
What part of DNA is tested for DNA profiling?-
The amount of base pairs repeated is what is used to determine matching DNA as it is nearly impossible for two individuals to have a matching number of base pairs.
Why does the DNA of different people appear at different locations in the Electrophoresis gel?
Upon completing the lab technicalities we saw that each persons DNA had a different pattern and that one matched the pattern found on the expo marker. we know the DNA appeared in these different patterns because each person has a unique amount of base pairs that can be heavy or light depending on amount causing them to move at different paces.
What causes the DNA to move through the Electrophoresis gel
the DNA has a negative charge so the positive charge on the opposite side causes the DNA to move. The DNA had a pattern in the gel because the larger the amount of base pairs the heavier it is (meaning it stayed nearer to the negative charge) and the DNA with less base pairs had a pattern nearer to the positive charge as it was lighter to move.