1. EVPP 110 Lab Molecules & Process of Life (Activities 3 - 5)
Week of February 12th, 2018

2. Molecules & Process of Life –
Activity 3 – DNA Extraction and Damage by a Pollutant

3. What is DNA?
Why is it important?
Where is it located in the cell?
Do all organisms have it?

4. 4. DNA is spooled onto a wooden stirrer.
1. DNA is in the nucleus of the cell (in eukaryotes).
2. The cell membrane is disrupted with a detergent.
DNA
3. Alcohol is added to the tube to separate DNA from other cell components and DNA migrates upward into alcohol layer.
4. DNA is spooled onto a wooden stirrer.
Alcohol
Protein and RNA
DNA

5. Soak strawberry in simulated pollutant.
Mash strawberry in plastic bag and mix with DNA extraction buffer.
Wait 5 minutes
Filter mashed mixture into tube.
Add enzymes (contact lens solution.)
Wait 2 minutes
Add cold alcohol.
It will form a layer at the top and DNA will rise.
DNA can be observed and spooled onto a wooden stirrer (do not stir – just twist).
Cheesecloth
Filter

6. Strawberry exposed to pollutant
Sketch appearance of both test tubes (normal and pollutant- exposed) containing the filtered strawberry mash, alcohol and DNA in Figure 3.1.
Normal strawberry
Strawberry exposed to pollutant
DNA
Alcohol
Water
Figure 3.1. Sketch of test tube and contents at end of DNA extraction procedure.

7. Table 3.1. Qualitative description of extracted DNA of strawberries, as viewed with unaided eye
Characteristic
Normal Strawberry
Strawberry Exposed to Pollutant
Color
Whitish
Purplish
Size
Really small, tough to see
Humungous
Quantity
A lot, huge amount
Very small amount, hard to find
Structure
Long strands
Record qualitative observations of the DNA (normal strawberry and exposed to pollutant) in Table 3.1.

8. Strawberry exposed to pollutant
Sketch of DNA (normal strawberry amd exposed to pollutant) as viewed through a microscope at 400X (Fig. 3.2).
Normal strawberry
Strawberry exposed to pollutant
Figure Sketch of extracted strawberry DNA stained with methylene blue and viewed with a compound light microscope at 400X.

9. Molecules & Process of Life –
Activity 4 – Diffusion and Osmosis – Part A

10. A form of passive transport.
Diffusion
A form of passive transport.
Movement of a substance from higher concentration to lower concentration.
Diffusion
Solute
High concentration Low concentration

11. Osmosis Special case of diffusion.
Solution A
Solution B
Water
Solute
Selectively permeable membrane
Solution A is hypotonic relative to Solution B
Solution B is hypertonic relative to solution A
Low solute concentration High solute concentration
High water concentration Low water concentration
Osmosis
Special case of diffusion.
Diffusion of water across a semi-permeable membrane.

12. Dialysis tubing
Comes flat in a roll.
To “open” your piece into a tube, hold it under running water and rub it between thumb and index finger.

13. Starch indicator solution
Iodine-based.
In absence of starch = “-”
Amber/yellowish color.
In presence of starch = “+”
Inky/blue-black color.

14. Glucose test strips
Test for the presence of glucose.
Container may be labeled “urine test strips”, “urinalysis” or “glucose” test strips.
Color changes in presence of glucose.

15. Make dialysis tubing “sausage”:
Close off bottom first; tie string tight to prevent leakage.
Use pipette OR squeeze bottle to add glucose + starch solution.
Close top; cut off excess string.
Rinse outside thoroughly.
Hold under running water and rub between thumb and forefinger to open
Put fluid in bag, fold over, tie
soak
Fold over and tie one end

16. Use pipette to add tap water to 2 wells on spot plate.
Put tap water in beaker.
Use pipette to add tap water to 2 wells on spot plate.
Test for starch in one well and glucose in the other.
Add starch indicator solution (iodine) to water in beaker.
Use pipette to add starch + glucose solution to 2 wells on spot plate.
Test for starch in one well, test for glucose in other well.
Place tubing sausage in beaker.
Iodine solution.
Dialysis tubing
Starch solution.

17. Record initial and final observations and test results (Table 4.1.)
Table Presence (+) or absence (-) over time of starch and glucose in beaker solution versus dialysis tubing solution, turgidity of dialysis tubing, color of beaker water, and tubing solution
Time (min)
Observation / Test
Container
Initial (0)
Final ( 60 )
Results of test for presence of starch
(“+” = positive, “-” = negative)
Beaker (+/-) +
Tubing (+/-) -
Results of test for presence of glucose (“+” = positive, “-” = negative)
Turgidity of dialysis tubing:
Color of beaker water after adding iodine:
Color of solution in tubing:
Evidence that water moved from tubing into beaker? (yes / no)
Evidence that water moved from beaker into tubing? (yes / no)

18. Molecules & Process of Life –
Activity 4 – Diffusion and Osmosis – Part B

19. Osmosis:
Special case of diffusion.
Diffusion of water across a semi-permeable membrane
Driven by differences in concentrations of water and solutes on either side of membranes.
Hypertonic
Isotonic
Hypotonic

20. Solution is hypertonic
Solution with a higher concentration of solutes (i.e. lower concentration of water) than the solution on the opposite side of the membrane.
Solution A is hypertonic relative to solution B.
Solution A has a higher concentration of salt (=solute) than solution B.
Solution is hypertonic A B
20% salt
Water moves out of cell
10% salt
= water molecules

21. Water moves in both directions
Isotonic
Solution has same concentration of solutes (and, therefore, a same concentration of water) as the solution on the opposite side of the membrane.
Solution A is isotonic relative to solution B.
Solution A has the same concentration of salt (=solute) as solution B.
Solution is isotonic A B
10% salt
Water moves in both directions
10% salt
= water molecules

22. Hypotonic Solution is hypotonic
Solution with a lower concentration of solutes (and, therefore, a higher concentration of water) than the solution on the opposite side of the membrane.
Solution A is hypotonic relative to solution B.
Solution A has a lower concentration of salt (=solute) than solution B.
Solution is hypotonic A B
10% salt
Water moves into cell
20% salt
= water molecules

23. Use wax marker to label three 25mL test tubes “A,” “B,” “C,”; place on test tube rack.
Use single-edge razor to cut three pieces of potato into approximately equal size cubes that can fit into a 25 mL test tube.
Determine mass (with electronic balance) of 1st potato cube, record initial mass (Table 4.2), place in tube “A.”
Determine mass of 2nd cube of potato, record initial mass, place in tube “B.”
Determine mass of 3rd cube of potato, record initial mass, place in tube “C.”
Table 4.2. Mass of potato cubes initially and after 1 hour in three solutions
Potato mass (g)
Solution A
De-ionized water B
0.9% saline C
9.0% saline
Time
Initial
After 1 hour
Difference =

24. Tube “A”: de-ionized water. Tube “B”: 0.9% saline solution.
Tube “C”: 9% saline solution.
Add enough liquid to cover the potato cube!
Table 4.2. Mass of potato cubes initially and after 1 hour in three solutions
Potato mass (g)
Solution A
De-ionized water B
0.9% saline C
9.0% saline
Time
Initial
After 1 hour
Difference =

25. Repeat for potato cubes in tubes “B” and “C”.
After 1 hour:
Remove potato cube from tube “A,” pat dry with paper towel, record mass (Table 4.2).
Repeat for potato cubes in tubes “B” and “C”.
Table 4.2. Mass of potato cubes initially and after 1 hour in three solutions
Potato mass (g)
Solution A
De-ionized water B
0.9% saline C
9.0% saline
Time
Initial
After 1 hour
Difference =

26. Determine and record the difference between the initial mass and the mass “after 1 hour” for the potato cube in each solution (Table 4.2).
Table 4.2. Mass of potato cubes initially and after 1 hour in three solutions
Potato mass (g)
Solution A
De-ionized water B
0.9% saline C
9.0% saline
Time
Initial
After 1 hour
Difference =

27. Molecules and Processes of Life –
Activity 5 – Photosynthesis and the Role of Environmental Parameters

28. The instructions, data sheets, and write-ups are posted in a file in the lab section on BlackBoard.

29. Photosynthesis:
Process by which certain organisms can make their own food (carbohydrates) using carbon dioxide, water and sunlight.

30. Environmental parameters can affect the rate of photosynthesis.
An increase or decrease in:
Reactant;
Availability of light energy; or
Temperature
Leads to an increase or decrease in the rate of photosynthesis (to an extent).

31. Carbon dioxide concentration
Rate of photosynthesis
Light intensity
Temperature
Carbon dioxide concentration

32. Site allows you to change three environmental factors that affect the rate of photosynthesis:
Temperature.
Carbon dioxide concentration.
Light intensity.

33. Rate of photosynthesis is shown by production of bubbles, representing production of oxygen gas (product of photosynthesis).
More bubbles = higher rate of photosynthesis.
Run all 18 combinations of environmental parameters.
Use timer function included in animation, count # bubbles produced during 30 seconds, record result.
Complete column headed “rate of photosynthesis # bubbles/min” by multiplying the value from the previous column by 2.

34. Rate of photosynthesis
Temperature
Light intensity
CO2
Total bubbles
Rate of photosynthesis 10 5
med 25 50
high 40
Table 5.2. Rate of photosynthesis as bubbles per minute for 18 combinations of three environmental parameters.

35. 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2
Median CO2
High CO2
Medium CO2
10 °C
25 °C
40 °C
# bubbles per minute
Figure 5.1. Rate of photosynthesis (bubbles per minute) at light intensity 5, medium and high concentrations of CO2 and three temperatures.

36. 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2
Median CO2
High CO2
Medium CO2
10 °C
25 °C
40 °C
# bubbles per minute
Figure 5.2. Rate of photosynthesis (bubbles per minute) at light intensity 25, medium and high concentrations of CO2 and three temperatures.

37. 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2
Median CO2
High CO2
Medium CO2
10 °C
25 °C
40 °C
# bubbles per minute
Figure 5.3. Rate of photosynthesis (bubbles per minute) at light intensity 50, medium and high concentrations of CO2 and three temperatures.

38. What’s Due Weekly Data Sheets (Due Today): P. 83 ,93 103.
Weekly Write-Ups (Due Next Class):
P , 97-98,
P. 83: OK to hand in hard copy
PowerPoint at