UMUC Biology 102-103 Lab 3 Cell Structure and FunctionPre-Lab Questions
Identify three major similarities and differences between prokaryotic and eukaryotic cells.
Where is the DNA housed in a prokaryotic cell Where is it housed in a eukaryotic cell
Identify three structures which provide support and protection in a eukaryotic cell.
Experiment 1: Cell Structure and Function
The structure of a cell dictates the majority of its function. You will view a selection of slides that exhibit unique structures that contribute to tissues function.
concept_tab_l
Materials:
Onion (allium) Root Digital Slide Images
Procedure
Examine the onion root tip digital slide images on the following pages. Then, respond to the Post-Lab Questions.
Onion Root Tip: 100X
Onion Root Tip: 100X
Onion Root Tip: 1000X
Onion Root Tip: 1000X
Onion Root Tip: 1000X
Onion Root Tip: 1000X
Onion Root Tip: 100X. Each dark circle indicates a different nucleus.
Onion Root Tip: 100X. Each dark circle indicates a different nucleus.
Onion Root Tip: 1000X
Onion Root Tip: 1000X
Post-Lab Questions
1. Label each of the arrows in the following slide image: A=Chromosomes, B=Nucleus, C=Cytoplasm, D=Cell Wall
Lab3_Experiment1_PostLabQuestion1
2. What is the difference between the rough and smooth endoplasmic reticulum
3. Would an animal cell be able to survive without a mitochondria Why or why not
4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria
5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.
Experiment 2: Osmosis – Direction and Concentration Gradients
In this experiment, we will investigate the effect of solute concentration on osmosis. A semi-permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. This selective permeability allows us to examine the net movement of water across the membrane. You will begin the experiment with a 30% sucrose solution, and perform a set of serial dilutions to create lower concentration solutions. Some of the sucrose concentrations will be membrane permeable; while others will not be permeable (can you determine why this is ).
concept_tab_2
Materials
(3) 250 mL Beakers
(1) 10 mL Graduated Cylinder
(1) 100 mL Graduated Cylinder
Permanent Marker
*8 Rubber Bands (2 blue, 2 green, 2 red, and 2 yellow)
60 g Sucrose (Sugar) Powder, C12H22O11
4 Waste Beakers (any volume)
*Paper Towels
*Scissors
*Stopwatch
*Water
*(4) 15 cm. Pieces of Dialysis Tubing
*Contains latex. Please handle wearing safety gloves if you have a latex allergy.
*You Must Provide
*Be sure to measure and cut only the length you need for this experiment. Reserve the remainder for later experiments.
Procedure
Use the permanent marker to label the three 250 mL beakers as 1, 2, and 3.
Cut four strips of dialysis tubing, each 15.0 cm long. Fill Beaker 3 with 100 mL of water and submerge the four pieces of dialysis tubing in the water for at least 10 minutes.
After 10 minutes, remove one piece of tubing from the beaker. Use your thumb and pointer finger to rub the tubing between your fingers; this will open the tubing. Close one end of the tubing by folding over 3.0 cm of one end (this will become the bottom). Fold it again and secure with a yellow rubber band (use
Tie a knot in the remaining dialysis tubing just above or just below the rubber band. This will create a seal and ensures that solution will not leak out of the tube later in the experiment.
To test that no solution can leak out, add a few drops of water to the tubing and look for water leakage. If any water leaks, tighten the rubber band and/or the knot in the tubing. Make sure you pour the water out of the tubing before continuing to the next step.
Repeat Steps 4 – 5 with the three remaining dialysis tubes, using each of the three remaining rubber band colors.
Reconstitute the sucrose powder according to the instructions provided on the bottle’s label (your kit contains 60 g of sucrose in a chemical bottle) . This will create 200 mL of a 30% stock sucrose solution.
Use Table 2 to create additional sucrose solutions that are 30%, 15% and 3% concentrated, respectively. Use the graduated cylinder and waste beakers to create these solutions. Set these solutions aside.
Table 2: Serial Dilution Instructions
Sucrose Solution
mL of Stock Sucrose Solution Needed
mL of Water Needed
30%
10
0
15%
5
5
3%
1
9
3%
1
9
Pour 150 mL of the remaining stock sucrose solution into Beaker 1.
Use some of the remaining stock sucrose solution to create an additional 200 mL of a 3% sucrose solution into Beaker 2.
Hint: Use your knowledge of serial dilutions to create this final, 3% sucrose solution.
Measure and pour 10 mL of the remaining 30% sucrose solution into the dialysis bag with the yellow rubber band. Seal the top of this tubing with the remaining yellow rubber band.
Measure and pour 10 mL of the 15% sucrose solution in the bag with the red rubber band, and seal the top of the dialysis tubing with the remaining red rubber band. 10 mL of the 3% sucrose solution in the bag with the blue rubber band, and seal the dialysis tubing with the remaining blue rubber band. The final 10 mL of 3% sucrose solution in the bag with the green rubber band. Seal the dialysis tubing with the remaining green rubber band.
Verify and record the initial volume of solution from each bag in Table 3.
Figure 8: The dialysis bags are filled with varying concentrations of sucrose solution and placed in one of two beakers.
Figure 8: The dialysis bags are filled with varying concentrations of sucrose solution and placed in one of two beakers.
Place the yellow, red, and blue banded tubing in Beaker 2. Place the green banded tubing in Beaker 1 (Figure 8).
Hypothesize whether water will flow in or out of each dialysis bag. Include your hypotheses, along with supporting scientific reasoning in the Hypotheses section at the end of this procedure.
Allow the bags to sit for one hour. While waiting, pour out the water in the 250 mL beaker that was used to soak the dialysis tubing in Step 1. You will use the beaker in Step 19.
After allowing the tubing to sit for one hour, remove them from the beakers.
Carefully open the tubing. The top of the tubing may need to be cut off/removed as they tend to dry out over the course of an hour. Measure the solution volumes of each dialysis bag using the 100 mL graduated cylinder. Make sure to empty and dry the cylinder completely between each sample.
Record your data in Table 3.
Table 3: Sucrose Concentration vs. Tubing Permeability
Band Color
Sucrose %
Initial Volume (mL)
Final Volume (mL)
Net Displacement (mL)
Yellow
Red
Blue
Green
Hypothesis:
Post-Lab Questions
1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.
2. Which tubing increased the most in volume Explain why this happened.
3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker
4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water
5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body Be sure to explain how this process works in terms of tonicity.
6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be Explain your answer using scientific evidence.
7. How is this experiment similar to the way a cell membrane works in the body How is it different Be specific with your response.
Our Service Charter
-
Excellent Quality / 100% Plagiarism-Free
We employ a number of measures to ensure top quality essays. The papers go through a system of quality control prior to delivery. We run plagiarism checks on each paper to ensure that they will be 100% plagiarism-free. So, only clean copies hit customers’ emails. We also never resell the papers completed by our writers. So, once it is checked using a plagiarism checker, the paper will be unique. Speaking of the academic writing standards, we will stick to the assignment brief given by the customer and assign the perfect writer. By saying “the perfect writer” we mean the one having an academic degree in the customer’s study field and positive feedback from other customers. -
Free Revisions
We keep the quality bar of all papers high. But in case you need some extra brilliance to the paper, here’s what to do. First of all, you can choose a top writer. It means that we will assign an expert with a degree in your subject. And secondly, you can rely on our editing services. Our editors will revise your papers, checking whether or not they comply with high standards of academic writing. In addition, editing entails adjusting content if it’s off the topic, adding more sources, refining the language style, and making sure the referencing style is followed. -
Confidentiality / 100% No Disclosure
We make sure that clients’ personal data remains confidential and is not exploited for any purposes beyond those related to our services. We only ask you to provide us with the information that is required to produce the paper according to your writing needs. Please note that the payment info is protected as well. Feel free to refer to the support team for more information about our payment methods. The fact that you used our service is kept secret due to the advanced security standards. So, you can be sure that no one will find out that you got a paper from our writing service. -
Money Back Guarantee
If the writer doesn’t address all the questions on your assignment brief or the delivered paper appears to be off the topic, you can ask for a refund. Or, if it is applicable, you can opt in for free revision within 14-30 days, depending on your paper’s length. The revision or refund request should be sent within 14 days after delivery. The customer gets 100% money-back in case they haven't downloaded the paper. All approved refunds will be returned to the customer’s credit card or Bonus Balance in a form of store credit. Take a note that we will send an extra compensation if the customers goes with a store credit. -
24/7 Customer Support
We have a support team working 24/7 ready to give your issue concerning the order their immediate attention. If you have any questions about the ordering process, communication with the writer, payment options, feel free to join live chat. Be sure to get a fast response. They can also give you the exact price quote, taking into account the timing, desired academic level of the paper, and the number of pages.