Biology 102/103 – Identify the major similarities and differences between prokaryotic

13 Jun Biology 102/103 – Identify the major similarities and differences between prokaryotic

Question
Biology 102/103
Lab 3: Cell Structure and Function
INSTRUCTIONS:

On your own and without assistance, complete this Lab 3 Answer Sheet
electronically and submit it via the Assignments Folder by the date listed in the Course
Schedule (under Syllabus).

To conduct your laboratory exercises, use the Laboratory Manual located under
Course Content. Read the introduction and the directions for each exercise/experiment
carefully before completing the exercises/experiments and answering the questions.

Save your Lab 3 Answer Sheet in the following format: LastName_Lab3 (e.g.,
Smith_Lab3).

You should submit your document as a Word (.doc or .docx) or Rich Text Format
(.rtf) file for best compatibility.

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Pre-Lab Questions
1. Identify the major similarities and differences between prokaryotic and eukaryotic cells.
Prokaryotes are small, single celled organisms like bacteria. Prokaryotes do not contain a
nucleus or any other organelle. Eukaryotes are larger, and often multi-cellular.
Eukaryotes are 15 times wider and up to 1,000 times greater in volume than
prokaryotes. Both eukaryotes and prokaryotes contain DNA, cell membranes,
cytoplasm, and ribosomes.

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?
DNA is housed in the nucleoid region of a prokaryotic cell and inside the nucleus of a
eukaryotic cell.

3. Identify three structures which provide support and protection in a eukaryotic cell.
1. Plasma/cell membrane- acts as a protective barrier
2. Cytoplasm- maintains cell shape
3. Cytoskeleton- provides structure and ability to move

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Experiment 1: Cell Structure and Function
Post-Lab Questions
1. Label each of the arrows in the following slide image:
A- Chromosomes
A

C
D

Onion Root Tip: 1000X

B
B- Nucleus
C- Cell wall
2. What is the difference between the rough and smooth endoplasmic reticulum?
The rough endoplasmic reticulum has ribosomes attached to the surface and the smooth
endoplasmic reticulum does not.

3. Would an animal cell be able to survive without a mitochondrion? Why or why not?
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No, an animal cell would not be able to survive without a mitochondrion, since the
mitochondrion is the power house of the cell, it takes in energy in the form of glucose and
converts it to ATP, which animal cells need to function.

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?
If the cell has a cell wall, but no nucleus or mitochondria, I could assume it is a prokaryotic
cell, most likely a bacterium.

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.
I would hypothesize that parts of plants, such as leaves and stems are green because they
are able to receive light, while parts such as the roots are not because they are not able to
receive sunlight. Since plants have chlorophyll, which makes them green and uses sunlight,
it is likely that only the parts that are reached by sunlight would be green.

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Experiment 2: Osmosis – Direction and Concentration
Gradients
Data Tables and Post-Lab Assessment
Table 3: Sucrose Concentration vs. Tubing Permeability
Band Color

Sucrose %

Initial Volume (mL)

Final Volume (mL)

Net Displacement (mL)

Yellow

30%

10mL

12.4mL

2.4mL

Red

15%

10mL

10.7mL

0.75mL

Blue

3%

10mL

9.3mL

-0.6mL

Green

3%

10mL

6.2mL

-3.8mL

Hypothesis: If the concentration of sucrose is higher in the beaker than in the dialysis
tubing, then the dialysis tubing will increase in volume.

Take a picture of your results. Include a note with your name and date on an index
card in the picture. Insert picture here:
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.

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Yellow- the solution inside was hypertonic

Red- the solution inside was hypertonic

Blue- the solution inside was isotonic

Green- the solution inside was hypotonic

2. Which tubing increased the most in volume? Explain why this happened.

The yellow tubing increased the most in volume. This is because of its hypertonic state,
the solution in the beaker was less concentrated than the solution in the dialysis tubing,
so through osmosis, it tried to balance by taking in more of the solution in the beaker,
traveling from high to low concentrations.

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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?

I don’t really understand this question? I suppose it shows the solution in the dialysis tubing
getting weaker while the solution in the beaker gets stronger.

4. What would happen if the tubing with the yellow band was placed in a beaker of distilled
water?

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If the tubing with the yellow band was placed in a beaker of distilled water, it would likely
burst due to being in a hypertonic state.

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.

Water from cells is moved to the area of low concentration, the salt accumulation in the
blood stream, and so on. Your body also processes these salts through your kidneys as well
as sweating them out, until it’s isotonic, or homeostasis is reached.

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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.

The minimum concentration of the beaker would have to be 51%, so that the solution in the
tubing (lower, at 50%) would try to flow to the solution in the beaker (higher, at 5%) in an
effort to create an isotonic solution on both ends, since you want solution to flow out of the
tubing.

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.