Lab 6 Paternity Testing

Lane/Well Numbers

Numbers assigned from left to right on the gel (1,2,3) to identify which sample is in each lane.

Sample/Tube Letter

The letter (A,B,C,D) that corresponds to the tube the sample came from; written above its lane

Sample Identity

A label describing what the sample is (e.g. Mothers DNA, Child DNA, Father 1 DNA)

Positive end of the gel

The bottom of the gel where DNA migrates toward; labeled with a "+”

Negative end of the gel

The top of the gel where the wells are located “-”

Marker Fragment sizes

The known base-pair sizes in the ladder (e.g. 6751, 3652, 2827, 1568, 1118, 825, 630)

Sample band sizes

Approximate fragment sizes in each sample, estimate by comparing the bands to the DNA ladder

What will travel farther in a gel? small or large fragments of DNA

Smaller fragments move faster in a gel

Is DNA positively or negatively charged

DNA is negatively charged

What are restriction enzymes?

Enzymes that recognize specific DNA sequences and cut there 

What is a RFLP and why does it cause bands of different sizes?

RFLP (restriction fragment length polymorphism) is the differences in the length of DNA fragments that result when restriction enzymes cut DNA at specific sites. Since each persons DNA sequence is slightly different, the enzymes cut at different places, creating fragments of various lengths that can be compared between individuals

What function do repetitive base sequences have in DNA?

Repetitive base sequences don’t have a function in DNA. When a DNA sequence is repeated, it can affect the size of DNA fragments. Repetitive base sequences make up 10-15% of the mammalian genome.

Could two people ever have the same DNA fingerprint?

Two people cannot have the same DNA fingerprint except identical twins. This is because everyone has minor differences in their DNA, which causes changes in where the restriction enzymes make their cut. This creates different sizes of DNA fragments, which are never identical, unless you have an identical twin.

Which potential father is the actual father of the child?

Father 1 is the biological father of the child because the child shares one band with the mother and 3 with Father 1 showing genetic contribution from both 

Why is the unrelated male not the father of the child?

The unrelated male is not the father of the child because his DNA does not match the childs unique fragment of DNA

What is DNA fingerprinting used for other than paternity testing?

DNA fingerprinting can also be used for crime investigations, missing persons, and identifying inherited disorders