Cell and Plasma Membrane

UMUC Biology 102/103
Lab 3: Cell Structure and Function
INSTRUCTIONS:
On your own and without assistance, complete this Lab 3 Answer Form electronically and submit it via the Assignments Folder by the date listed on your Course Schedule (under Syllabus).
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Experiment 1: Labeling (consult the Lab 3 Introduction for more details)

Bacteria: Nucleoid region, cell wall, plasma membrane, ribosomes, flagella

Protist: Macronucleus, micronucleus, plasma membrane, cytoplasm, contractile vacuole

Plant Cell: Nucleus, cell wall, plasma membrane, cytoplasm, chloroplast, mitochondria, vacuoles

Animal Cell: Nucleus, nucleolus, plasma membrane, cytoplasm, mitochondria, golgi apparatus, rough ER, ribosome

Questions
1. For each structure identified, do you think its location affects its ability to function? Why or why not? (Hint: those buried deep in the cell probably do different things than those closer to the cell membrane)

The cell is structured to where everything within the cell is able to work very efficiently. The protein building process starts deep within the cell and reaches the outer parts of the cell as the protein reaches completion.

2. Draw a labeled diagram of a small section of the plasma membrane and briefly describe its structure and function.

3. Describe the differences between animal and plant cells.

Both, animal and plant cells have eukaryotic cells. Animal cells have centriole and lysosome which will not be found in plant cells. The plant cell contains central vacuole, cell wall, and chloroplast (for photosynthesis) which you will not find in an animal cell.

4. Which of the following structures are present in both prokaryotic and eukaryotic cells?

Plasma membrane, cytosol, chromosomes, ribosomes

5. Where is genetic material found in plant cells?

DNA in the nucleus

6. Mitochondria are the only organelles that contain their own DNA (circular) and have a double membrane. Why do you think this might be so?

Mitochondria may have evolved from prokaryotes

Hint 1: Where else do we see circular DNA?)
Hint 2: What do you know about the relative age of eukaryotic cells?)

7. How is the structure of the plant’s cellulose-based cell wall related to its function?

Cellulose forms fibrils in the walls that enclose plant cells. It is a major component of wood and other structural components of plants. The cellulose based cell wall protects the cells, maintains cell shape, and keeps the cell from absorbing so much water that they burst.

8. Defects in structures of the cell can lead to many diseases. Pick one structure of a eukaryotic cell and develop a hypothesis as to what you think the implications would be if that structure did not function properly.

The lack of energy is a result of the mitochondria inability to produce sufficient amounts of ATP.

9. Using books, articles, the internet, etc. conduct research to determine if your hypothesis was correct.

My hypothesis seems correct, however there are many other symptoms that occur when one has mitochondrial disease.

http://www.medicinenet.com/mitochondrial_disease/article.htm

Experiment 2: Directions and Concentration Gradients

Table 2: Water Movement
Initial Volume
Sucrose %
Prediction: Will water move in or out?
Final Volume
Bag #1 10 mL
30
Out
16
Bag #2 10 mL
15
Out
12
Bag #3 10 mL
3
In
9
Bag #4 10 mL
3
in
7

Questions
1. For each of the bags, identify whether the solution inside was hypertonic, hypotonic or isotonic in comparison to the beaker solution it was placed in.

The solution in Bag #1 was hypertonic.
The solution in Bag #2 was hypertonic.
The solution in Bag #3 was isotonic.
The solution in Bag #4 was hypotonic.

2. Which bag increased the most in volume? Why?

Bag #1 increased the most because the water will move to higher sucrose concentrations. The sucrose was unable to move through the membrane which led to the water being drawn into bag #1.

3. What does this tell you about the relative tonicity between the contents of the bag and the solution in the beaker?

Water is able to diffuse through the membrane and will move to the higher concentrated solute until both concentrations are equal. The solute is hypertonic when the concentration is higher in the membrane. It is isotonic when it is equal and it is hypotonic when the solute in the membrane has a lower concentration.

4. What would happen if bag 1 is placed in a beaker of distilled water?

The volume would have increased more than if it would have been placed into a 3% solution.