Question

looking for answers only questions #4 And #5 and #6
1 1 - + O Fit to page Page View A Read aloud Add notes 6 8 % 1. Why do individuals have two copies of each STR region? (Hint: Humans have maternal and paternal chromosomes.) Below is a DNA profile of three individuals using two different STRs: AGGCT and CAATG ) The DNA profile below shows the band pallerns of three individuals that resulted from gel electrophoresis separating the DNA fragments for the two STRs. The DNA from each individual was added at the top of the gel. The numbers along the left side of the gel represent how many times each DNA STR is repeated. For example, if a band is at 7, the STR sequence would be repeated 7 times and if the band is at 3, the STR sequence would be repeated 3 times, making the DNA fragment at 7 longer than the DNA fragment at 3. Remember, the shorter the DNA fragment the further it travels through the gel (v). Please refer to Infographic 7.5 and 7.6 in the textbook for more information to complete this activity. Individual 1 Individual 2 Individual 3 DNA added here-> Using the DNA profile above answer the following questions: 2. How many times is the STR (AGGCT) repeated for each of the two DNA bands for individual 12 3. What would be the reason individual 2 has one thick DNA band for AGGCT?

Answer 1

4. 5 times. Because the DNA band at number 5 or near to will repeat for CAATG sequence 5 times, these band are depicted in orange in the given figure.

How DNA fragments separate in gel Electrophoresis :- When the samples are loaded and allowed to separate they separate according to the size. The fragment with large size will not move to the longer distances where as the fragment with the short size will move to longer distances.

5. Individual 2

6. Individual 3

By calculating the number of STR repeating sequences we can easily determine the the length of the fragment. for above example, individual has more STR repeating sequences than individual 2