BLOCK 5-2 week-6TOPIC: genetics testing OBJ: 11-12DO NOW: EXT: DUE DATE: DW: 13.2 LAB

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EXIT: CIRCLE-level of understanding of today’s objectiveON BACK NONE

HANDOUTS to PICK-UP:-13.2 LABTURN IN to ABS box:

SEMINAR 2:

BEFORE/AFTER SCHOOL:DW: 13.2 VIRTUAL LAB

-DW13.2 VIRTUAL LAB-ELECTROPHORESIS LAB

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GENERAL

BLOCK

LEVEL OF UNDERSTANDING

DW GRADE __________ / __________

13.2 VIRTUAL LAB

5

Write this in your Weekly Organizer in RED PEN

13.2 VIRTUAL LAB-GRADE RUBRIC

5-WHAT IS EXPECTED-All areas COMPLETED

3-ALMOST WHAT IS EXPECTED

-50% COMPLETED

0-NOT COMPLETED

GEL ELECTROPHORESIS1-What is your job?  -determine lengths of DNA2-IDENTIFY the FUNCTION of GEL ELECTROPHORESIS?  -SORT & MEASURE DNA strands by length3-How does GE work?  -gel acts as a filter

-separates molecules (electrical charge) -sorts DNA strands (banded pattern)

SEQUENCE steps of DNA moving thru gel

GEL ELECTROPHORESIS4-Do LONG or SHORT strands move more quickly thru the gel?  -SHORT

5-Can we see single strands of DNA in the gel?  -NO—they are too small even under a microscope

GEL ELECTROPHORESIS6-LIST 5 basic steps of GE-______________________________________-______________________________________-______________________________________-______________________________________-______________________________________ MODEL 5 steps of GE with picture procedures

Make gel

Set up apparatus

Place DNA samples in holes at end of gelADD electric current

Stain-ANALYZE

GEL ELECTROPHORESISWALK THRU LAB7-DETERMINE what each is made of

AGAROSE: -seaweedBUFFER: -salt water solution

8-why do buffer & agarose need to be heated?  -melt agarose into buffer9-why does the mold have tape on each end?

-holds melted agarose10-IDENTIFY why a COMB placed in the gel at one end

-makes “wells” (small holes) to hold DNA samples 11-ANALYZE 2 reasons buffer solution is added to GE box

-conducts electric current -keeps gel from drying out

GEL ELECTROPHORESIS12-DETERMINE 2 functions of loading buffer

-contains a dye making sample easy to see-makes DNA sample thicker so it doesn’t float away 

13-PREDICT in a real lab difficulties loading samples   -NOT easy—might take some practice 14-why would we use a standard DNA size sample?

-contains DNA strands of known lengths-provides reference to estimate lengths of DNA

strands15-CONCLUDE why electricity is used to run the wells

-DNA negative charge attracted to + charge

GEL ELECTROPHORESIS16-how can you check to make sure your current is running?

-should see tiny bubbles17-does DNA move to + or – end?

-+18-why is the gel stained and how does it work?

-cannot see DNA but can see dyes -can see large groups of stained DNA strands-dye binds to DNA-shows up under flouresent lights

GEL ELECTROPHORESIS19-ENTER bp— base pairs —size estimates

-6000-3500-1500

13.2 LAB

OBJECTIVE:-student will DEMONSTRATE the separation technique known as gel electrophoresis.

-student will use this process to IDENTIFY dye samples by molecular mass.

-student will use this information to IDENTIFY the composition of an UNKNOWN mixture of dyes found at crime scene

13.2 LABINTRO/ BACKGROUND:-How can a mixture of molecules, too small to be seen with even a high-powered microscope, be separated from one another? Such was the dilemma facing scientists until the development of a process that has now become standard in many laboratories worldwide- gel electrophoresis.

-Laboratories rely heavily on this proven and reliable technique for separating a wide variety of samples, from DNA used in forensics and for mapping genes, to proteins useful in determining evolutionary relationships.

-In 1950 gel electrophoresis was invented. The process involves applying an electrical current to a gelatin-like substance containing biological samples. When mixtures of materials are placed within the wells of the gel and an electric current is applied, the molecules travel through the gel and separate from one another according to each molecule’s charge, size, shape. The gel acts as a type of molecule strainer and prevents all the molecules from moving too quickly. Smaller molecules typically mover through the gel at a faster rate than the larger ones. When the current is turned off, all the molecules are stopped within the gel. If a dye is added to the samples placed in the wells, individual groups of molecules can be identified by a distinct, colored band within the gel. When the distance each band (group of molecules) traveled is measured and compared to the other colored bands within the gel, the measurement can readily distinguish smaller molecules from larger molecules

13.2 LABPROBLEM:Yesterday, there was a home break-in. No fingerprints were found at the scene but forensic investigators found multiple threads of what appears to be clothing. The thread’s colored was unable to be determined as it appears the clothing was also slightly burned, thereby affecting the ability to see the color. Since many clothing dyes are made from plants, the DNA can be extracted from the dye of the cloth and matched with the crime scene thread. Here is the list of suspects:

1-Dereck Simien – 49, Male, wore a green t-shirt at the time of the robbery2-Jamie McDonald – 33, Female, wore an burnt orange hoodie at the time of the robbery3-Martha Dougal – 34, Female, wore a blue denim coat at the time of the robbery4-Louis Castillon – 20, Male, wore a red jacket at them time of the robbery5-Scott Hackman – 25, Male, wore a K-State polo at the time of the robbery

GEL ELECTROPHORESIS

1- Gather needed materials and make sure working area is ______________ and ____________. 2- Place the electrophoresis unit in a ____________________ position on the countertop. 3- Place the “gel drawing worksheet” on the counter next to or below the electrophoresis unit.  4- Number the wells on the paper from #1 at the _______ to #6 at the __________. 5- Withdraw ________microL of dye from each tube by filling only the needle tip of the pipet. 6- USE A CLEAN PIPET FOR EACH DYE SAMPLE TO AVOID CONTAMINATION. 7- Make sure you follow the data table for the correct dye in each numbered well. 8- Once all dyes have been transferred to the wells, NOTIFY YOUR TEACHER-

-The TEACHER will load your gel into the electrophoresis unit.

CLEANDRY

HORIZONTAL

LEFT RIGHT

6

PART 4: Testing for the HD gene

LOADING INSTRUCTIONS:GETTING THE SAMPLE

PART 4: Testing for the HD gene

LOADING INSTRUCTIONS:LOADING THE GEL

1 2 3 4 5 6

13.2 LABPRE-LAB Q’s:-Using the information in the chart / background knowledge answer the following questions.

1-PREDICT the DIRECTION of migration for each unknown dye sample. (+ or -)GREEN + -ORANGE + -BLUE + -RED + -PURPLE + - 

2-PREDICT which dye will move through the gel the: FASTEST ______________ SLOWEST ______________

 

13.2 LABPRE-LAB Q’s:3-LIST a BRIEF FUNCTION for each part used in gel electrophoresis

AGAROSE GEL--”microscopic strainer” / separates BIG molecules

from SMALL

BUFFER--conductor / carries electric current

WELLS IN GEL--hold the DNA sample

ELECTRIC CURRENT--provides force that MOVES the sample

13.2 LAB15- Use the [GEL DRAWING] template to make an accurate drawing of the bands in the gel.

-USE COLORED PENCILS 16- Measure the distance each gel migrated in mm. Record in data table.[DATA TABLE] 17- Record the charge for each dye molecule by noting which pole (+/-) the dye sample was traveling when the power was shut off. [DATA TABLE] 18- Use the recorded migration distances to complete the last column of the data table by ranking the five known dye samples from fastest (#1) to slowest (#5) [DATA TABLE] 19- CLEAN-UP lab station.

_____- dispose of gel in trash can_____- rinse AND dry petri dish (return to cart in front of room)_____- wipe down lab station_____- return all equipment to original location. [see board for

reminder of location]