Assessment Task – Year 11 – Term 4, 2016
Human Biology General Unit 2
Task Description: Gel electrophoresis and DNA profiling
This investigation will help you to understand the process of gel electrophoresis and its applications in the
different areas of science, forensics and medicine.
Background:
Students are required to plan and conduct investigations in which they
 analyse data, draw conclusions, evaluate investigation design and findings
 evaluate the impact of advancements in human biology on individuals and society
 communicate understandings of human biology.
Learning
Outcomes
 Science
understanding
 Science
inquiry skills
Assessment
Description
PART A:
This investigation requires you to plan your own
experiment. You will be working in a group to develop
the aim, hypothesis, what materials & equipment to use,
the method and how you will record your results. You
will be doing this preliminary planning stage in class.
You will be individually assessed.
Pre-lab groupwork 13
 Science as a
human
endeavour
PART B:
Gel electrophoresis experiment
Investigation
PART C:
You will be required to complete a worksheet
Worksheet
Student:
_____________________________________
PART A
13
Teacher: Mrs Brown
PART C
14
TOTAL
27
PART A
BACKGROUND INFORMATION
Gel electrophoresis is a method of separating compounds into their component chemicals. It can be
used for a range of substances, including DNA and dyes. Gel electrophoresis is used extensively in
DNA profiling for a number of applications in different areas of science. It is based on the principle
that you should be able to identify an unknown substance by comparing it to the properties of known
substances. In the case of gel electrophoresis, it is through the comparison of band patterns that
unknown substances can be identified.
This investigation will dyes instead of DNA to simulate the process so that you can gain an
understanding of gel electrophoresis. You will be given 4 known dyes and 2 unknown mixtures of
these dyes. You will be required to identify the mixtures. The dyes are as follows:






Bromophenol blue
Methyl green
Orange G
Xylene cyanol
Mixture A
Mixture B
AIM
1. Discuss and develop the aim for this investigation.
(2 marks)
VARIABLES
2. Discuss and decide on the independent variable and the dependent variables for this
investigation.
Independent variable
(1 mark)
Dependent variables
(2 marks)
2
HYPOTHESIS
3. Discuss and develop an hypothesis for this investigation
(2 marks)
MATERIALS & EQUIPMENT
Materials & equipment
 Agar gel
 Electrophoresis kit
 Buffer solution
 Micropipette
 Food dye
 Plastic gel molds
There are 2 kits available
METHOD
Agar gel
 Put a fresh tip onto the micropipette
 Practice using the micropipette to place one of the food dyes into the plastic mold until you are
confident with the procedure.
 Discard the used tip and place a fresh one on the micropipette.
 Select the food dyes you will be testing
 Decide on the order the food dyes will be placed into the agar gel slits
 Using the micropipette, select the first food dye and place the required amount into the first
agar gel slit.
 Discard the used tip and place a fresh one on the micropipette.
 Repeat steps 4 & 5 until all of the dyes have been placed into the slits.
Electrophoresis chamber & power supply
 Place the gel into the electrophoresis chamber.
 Add the buffer solution until it is just covering the agar gel.
 Place the lid on top of the chamber.
 Plug the leads into the power supply.
 Set the power supply to run at 100 volts for 5 minutes.
 After 5 minutes, reduce to 40 volts and let it run for at least an hour.
 Check regularly for results.
3
4. What steps will need to be taken to ensure that all variables are controlled and the results will be
valid and reliable?
(4 marks)
RESULTS
5. Discuss and decide on the how data will be collected and presented.
(2 marks)
4
PART C
RESULTS
Describe your observations
(4 marks)
5
CONCLUSION
6. What can you conclude from the results?
(4 marks)
Mixture A:
Mixture B:
DISCUSSION
Short tandem repeats are the sections of DNA that are used in DNA profiling. Every person has a
unique combination of STR’s. Closely related individuals have more STR’s in common than people
who are unrelated. Each person’s STR’s will form a unique band pattern in gel electrophoresis. This
is sometimes called a DNA ‘fingerprint’.
7. What are the applications for gel electrophoresis and DNA profiling in:
(6 marks)
Criminal investigations
Genetic counseling
Paternity testing
6