HeLa Cell Lab Observing Chromosomes

Vocabulary Diploid – The state of the cells in which all chromosomes are two in number and structurally identical with those of the species from which it is derived. Chromatids – A strand of chromosome attached to another chromosome through a centromere Centromere – The region of a chromosome where the chromatids are held together Histones – Proteins associated with DNA in the chromosomes. Help the DNA fold to compact within the chromosomes. Metaphase – The state of mitosis where chromosomes are fully developed but attached on the equatorial plane with a spindle fiber. The easiest state to study chromosomes.

Facts Diseases can be genetically inherited. – Autosome Chromosome not involved in determining sex (chromosomes 1-22) – Hereditary Transmission of traits from ancestor to descendent – Sex chromosomes Chromosomes involved in determining sex (chromosome 23) Instructions on chromosomes determine traits Genetically inherited traits are found on chromosomes

HeLa Cell Lab Observe Human Chromosomes – Tumor cell line grown in a laboratory to see chromosome spread – This line is created in a laboratory from Henreitta Lacks in 1951.

Step 1 Get the following pieces of equipment – Transfer pipette – Bulb – Microscope Slide Place your initials on the edge of the slide using a sharpie.

Step 2 Place the microscope slide at a 45 degree angle

Step 3 GENTLY Resuspend cells in tube – Slowly pipette the cells in the tube 3 times

Step 4 Practice with WATER before Attempting the drop!!!!!! Remove a SMALL sample of the cell suspension into the pipette. Hold the pipette 2 feet above the microscope slide Allow 1 drop of suspension to “splat” onto the slide – Hit the upper end so the suspension will flow down towards the ground. Apply 5 more drops – But only place 1 drop at a time!!!!

Step 5 Place the slide horizontally on the lab bench. You may GENTLY blow on the slide to dry it. IT MUST BE DRY BEFORE PROCEEDING TO STEP 6!!!!!

Step 6 Dip the slide into Stain #1 for 1 second (use clamps!!!!!!!!!!) Remove the slide REDIP the slide into Stain #1 for 1 second Remove the slide REDIP the slide into Stain #1 for 1 second Remove the slide Allow the stain to COMPLETELY DRAIN OFF THE SLIDE Wipe the bottom of the microscope slide with a paper towel.

Step 7 Dip the slide into Stain #2 for 1 second Remove the slide REDIP the slide into Stain #2 for 1 second Remove the slide REDIP the slide into Stain #2 for 1 second Remove the slide Allow the stain to COMPLETELY DRAIN OFF THE SLIDE

Step 8 Completely remove the stain from the microscope slide by rinsing the slide – USE THE WATER BOTTLE AT THE BENCH – DO NOT USE THE SINK!!!!!!

Step 9 Allow the slide to air dry

Step 9 Place 2 drops of the permount to the stained area on the slide. Place a coverslip over where the permount is located. – Gently apply pressure to the coverslip – If there is a large stained area, you can place 2 coverslips side by side

Step 10 Observe the chromosomes at all 4 objectives using the microscopes. – Move the microscope slide around until you find 5 cells that have cracked open – You will be able to see the chromosomes spilled out on the slide! – REMEMBER, YOU WILL ONLY USE THE 100X OPTICAL LENS WITH OIL IMMERSION Draw what you see at the 100X view.

Step 11 Draw the chart on a sheet of paper: Cell SpreadNumber of Chromosomes Counted

Step 12 Count the number of chromosomes in 5 different cells. Record the results in the chart. Record the results of the other group at the table in your chart as well. Draw one cell (at the highest objective) on your paper as well. – Take your time and detail your drawing.

Step 6 Answer these questions and then turn in your lab sheet: 1. Did each of the cell spreads have the same number of chromosomes? 2. Did the number of chromosomes you counted in the cell spreads differ from the normal number of human chromosomes in a cell? If the counts were different, how did they differ? 3. Describe how the chromosomes within a single spread were similar or different from each other. 4. Describe how the chromosomes of different cell spreads were similar or different from each other. 5. Describe what you would expect to see if you made a chromosome spread of non-cancerous human cells. 6. Why do all the normal cells in the human body have the same number of chromosomes?