Lab 3: Cell Structure and Function

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Lab 3: Cell Structure and Function.

Lab 3: Cell Structure and Function

 

INSTRUCTIONS:

 

 

 

·         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.

 

 

 

 

Pre-Lab Questions

 

  1. Identify three major similarities and differences between prokaryotic and eukaryotic cells.

     

  2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?

     

     

  3. Identify three structures which provide support and protection in a eukaryotic cell.

     

 

 

 

Experiment 1: Cell Structure and Function

 

 

 

Label each of the arrows in the following slide image:

 

 

 

 

Post-Lab Questions

 

 

 

 

 

  1. What is the difference between the rough and smooth endoplasmic reticulum?

     

     

     

     

  2. Would an animal cell be able to survive without mitochondria? Why or why not?

     

     

     

     

     

  3. 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?

     

     

     

     

  4. 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

    Data Tables and Post-Lab Assessment

    Table 3: Sucrose Concentration vs. Tubing Permeability

     

 

Table 3: Sucrose Concentration vs. Tubing Permeability
Band Color % Sucrose in Beaker % Sucrose in Bag 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?

 

 

 

 

 

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

     

  2. 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.

     

  3. 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.

     

  4. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.

    Lab 3: Cell Structure and Function

    INSTRUCTIONS:

    · 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.

    Pre-Lab Questions

    1. Identify three major similarities and differences between prokaryotic and eukaryotic cells.

    2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?

    3. Identify three structures which provide support and protection in a eukaryotic cell.

    Experiment 1: Cell Structure and Function

    Label each of the arrows in the following slide image:

    image1.png

    Post-Lab Questions

    1. What is the difference between the rough and smooth endoplasmic reticulum?

    2. Would an animal cell be able to survive without mitochondria? Why or why not?

    3. 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?

    4. 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

    Data Tables and Post-Lab Assessment

    Table 3: Sucrose Concentration vs. Tubing Permeability

    Table 3: Sucrose Concentration vs. Tubing Permeability
    Band Color % Sucrose in Beaker % Sucrose in Bag 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.

    ©eScience Labs, LLC 2014

    image2.jpg

Lab 3: Cell Structure and Function

 
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LAB 5 BIO 100

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LAB 5 BIO 100. Compose answers to the questions below and save the file as a backup copy in the event that a technical problem is encountered while attempting to submit the assignment. Make sure to run a spell check.

You will be submitting your answers to the lab assignment in two parts. The first part of the lab assignment consists of the laboratory exercise questions. The second part of the lab assignment is the application question. The first textbox on the submission page corresponds to the first part of the lab. Be sure to paste the laboratory exercise questions, with your answers, into this textbox. The second textbox on the submission page will be for your response to the application question.

 

LABORATORY EXERCISE QUESTIONS

 

~~1.

a. What is the name of the pigment that captures light directly in photosynthesis? (2 points)

b. Why does the pigment appear green? (2 points)

~~2. List two variables besides the wavelength (color) of light which might affect the rate of food production in plants. (4 points)

a.

b.

~~3. Why is chlorophyll important for all biological life? (5 points)

~~4.

a. In Part I of the procedure, what is the name of the indicator used to identify the presence of CO2? (2 points)

b. What color did the indicator turn after blowing air into the water through the straw? (2 points)

~~5.

a. What color did the indicator turn after the tube was placed under a light source for 30 minutes? (2 points)

b. Why did this occur? (3 points)

 

 

 

~~6. List the functions of these four common pigments found in plants. (4 points)

a. Chlorophyll a

b. Chlorophyll b

c. Xanthophyll

d. Carotene

~~7. If the Rf factor of a pigment is .3750 and the distance that the solvent traveled is 8 cm, how far did the pigment travel? (5 points)

~~8. List the Rf values for each of the pigments extracted from the spinach leaves, as seen in the chromatography procedure (4 points).

a. Carotene

b. Xanthophyll

c. Chlorophyll a

d. Chlorophyll b

~~9. Based on the results, which pigment has the highest molecular weight? (5 points)

~~10. From the chromatography lab, which pigments were soluble in the acetone? (5 points)

~~11. The earth’s early atmosphere did not contain oxygen. This changed dramatically once the early cells underwent photosynthesis.

a. Explain how photosynthesis was able to occur in earth’s early atmosphere. (5 points)

b. How did photosynthesis eventually affect the evolution of other organisms? (5 points)

~~12.

a. In reviewing the data from the floating disk experiment, which factor had a greater impact on the rate of photosynthesis (light intensity or concentration of carbon dioxide)? (5 points)

b. Explain how you came to this conclusion? (5 points)

 

 

 

 

 

 

 

 

 

**INFORMATION NEEDED TO COMPLETE THE FOLLOWING PROBLEMS**

Independent Variable: This is the cause.

Dependent Variable: This is the response or effect.

One hundred samples of several different plants were placed in each of six sealed containers with water in them. At the end of two days the amount of oxygen produced was measured. Results are shown in the table below.

Container

 Plant Height of Plant Light Intensity Source of Light Distance from Light mL O2 Produced
1 Iris 4″ High Artificial 6″ 16
2 Iris 4″ High Natural 6″ 13
3 Iris 6″ Low Artificial 5″ 12
4 Carnation 6″ High Natural 4″ 13
5 Carnation 6″ Low Natural 4″ 9
6 Carnation 4″ Low Artificial 5″ 14

 

~~13. Multiple Choice: Based on the data presented in the table, which two containers could be correctly used to compare the rate of photosynthesis at two different light intensities? (5 points)

a. 1 and 2

b. 2 and 3

c. 1 and 5

d. 5 and 6

e. 4 and 5

~~14. Multiple Choice: Compare Containers 1 and 2. What independent variable is tested by this comparison? (5 points)

a. Kind of plant

b. Height of plant

c. Light intensity

d. Distance from light source

e. Light source

~~15. Multiple Choice: Which container had the slowest rate of photosynthesis? (5 points)

a. 1

b. 2

c. 3

d. 4

e. 5

f. 6

 

APPLICATION QUESTION

 

~~16. (Application) How might the information gained from this lab pertaining to photosynthesis and pigments be useful to you, or how can you apply this knowledge to your everyday life as a non-scientist? The application will be graded according to the rubric below. (20 points)

LAB 5 BIO 100

 
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SCI 115 Week 6 Lab Quiz

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SCI 115 Week 6 Lab Quiz. QUESTION 1

1. Most scientists who use DNA microarrays obtain them

 

from   companies that mass produce them

 

from   the government

 

by   making them in their labs

 

by   exploiting ambitious graduate students

QUESTION 2

1. “In this study, cancerous and normal skin tissue samples were excised with a scalpel. Each skin sample was then placed into a sample tube along with solvent, shaken on a vortex and centrifuged. When the sample tubes came out of the centrifuge, there was a top layer and a bottom layer. For our purposes, we went on to use ______________ for further processing.”

 

only   the top layer

 

only   the bottom layer

 

a   mixture of top and bottom layers

 

none   of the options listed

QUESTION 3

1. The purpose of the vortex instrument is to

 

vigorously   shake the tissue sample in the solvent so that it dissolves.

 

spin   the tissue/solvent mixture around to separate the solids

 

cause   the mRNA to bind to the pellets

 

dispose   of biohazardous waste safely

QUESTION 4

1. “Once the RNA is isolated from the DNA, proteins and other materials, the solvent/RNA mixture is run through a column of all beads. Each bead has several short strands of polyT RNA sticking out of it. In this step:”

 

“mRNA   sticks to the beads, while rRNA and tRNA run right through the column”

 

“tRNA   sticks to the beads, while mRNA and rRNA run right through the column”

 

“rRNA   and tRNA stick to the beads, while mRNA runs right through the column”

 

none   of the options listed

QUESTION 5

1. “Once the mRNA is isolated, you make a DNA copy of it using by adding polyT primers, labeled DNA nucleotides, and an enzyme known as:”

 

reverse   transcriptase

 

tyrosine   hydroxylase

 

alcohol   dehydrogenase

 

ATP   kinase

QUESTION 6

1. A DNA copy of a mRNA transcript is known as

 

complementary   DNA (abbreviated cDNA)

 

copied   DNA (abbreviated cDNA)

 

mitochondrial   DNA (abbreviated mtDNA)

 

recombinant   DNA (abbreviated rDNA)

QUESTION 7

1. Each spot on the DNA microarray in embedded with

 

copies   of DNA from one particular gene

 

copies   of DNA from several different genes with similar functions

 

copies   of DNA from several different genes with different functions

 

copies   of mRNA from one or more genes

QUESTION 8

1. “When we say that the cDNA derived from our sample has hybridized to a particular spot on the array, we mean that: ”

 

The   cDNA from the sample has stuck to the DNA on the microarray at that point.

 

The   cDNA from the sample is jumbled and cannot be trusted.

 

The   cDNA has been used to make an mRNA copy

 

You   need to buy microarrays from different manufacturers and triangulate the   results

QUESTION 9

1. “In this particular experiment, we used red-labeled DNA to process the sample from _____________ tissue and the green-labeled DNA to process the sample from ___________. ”

 

cancerous;   normal

 

normal;   cancerous

 

normal;   normal

 

cancerous;   cancerous

QUESTION 10

1. “After scanning the green labeled areas and the red labeled areas, when we combine the two images, the spots that show up as yellow correspond to ”

 

genes   expressed by both normal or cancerous skin cells.

 

genes   that were not expressed at all in either normal or cancerous skin cells

 

“genes   expressed by cancerous, but not normal skin cells”

 

“genes   expressed by normal, but not cancer skin cells. ”

QUESTION 11

1. “In interpreting the results of this study, spots on the microarray that are red correspond to:”

 

genes   that are turned up by cancer

 

genes   that are turned down by cancer

 

genes   that are unaffected by cancer

 

genes   that aren t expressed in normal or cancerous cells

QUESTION 12

1. “In interpreting the results of this study, spots on the the microarray that are green correspond to genes that are ”

 

genes   that are turned down by cancer

 

genes   that are turned up by cancer

 

genes   that are unaffected by cancer

 

genes   that aren t expressed in normal or cancerous cells

QUESTION 13

1. “When the DNA microarray study tells us that a large number of genes have been turned up (or turned down) by a disorder, the most likely explanation is that ”

 

the   turned up genes are likely controlled by a gene that has gone bad

 

all   of these genes are genes that have gone bad themselves

 

even   just one mutation in any of these affected genes would have been sufficient   to cause the disorder

 

the   cytoplasm has too many free radicals in it

QUESTION 14

1. A gene shown by the microarray to be expressed is :

 

“probably   making protein, but a protein expression analysis would be needed to know for   sure”

 

definitely   making protein

 

definitely   not making protein

 

probably   making protein but there’s no way to know for sure

QUESTION 15

1. “In the application of this technique to skin cancer, a gene that has gone bad ”

 

“may   or may not be identified at all, but the overall pattern of results can give   important clues”

 

can   almost always be identified via DNA microarray

SCI 115 Week 6 Lab Quiz

 
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Ways to Fight Cancer

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Ways to Fight Cancer. 1. Read the course textbook’s chapter on cell division, specifically the last section on how cells become cancerous. This is context for completing Individual Assignment 3.

2. Watch the Presentation in Module/Week 9 entitled “Ways to Fight Cancer.” Notice that the presentation outlines essentially 3 approaches to fighting cancer: a) reduction of cancer risks, b) correction of cancer genes, and c) destruction of cancerous tissue.

3. Open the “10 Discoveries in the War on Cancer” document in the Assignment Instructions folder. Scan the discoveries briefly. Then, open the assignment submission link in Module/Week 9. In the text box, number from 1 to 10 for the 10 discoveries.

4. Reflect carefully on discovery 1. Would this discovery be more useful for a) reducing cancer risks, b) correcting/restoring cancer cells to normal, or c) destroying cancerous tissue? After number 1 in your list, place in parentheses the letter representing the approach to fighting cancer that will best be served by this new discovery. (More than 1 approach may be served, but which is most likely to be helped most significantly?)

5. Repeat this analysis for each of the remaining 9 discoveries. Return to the “Ways to Fight Cancer” presentation as needed for additional perspective. When finished, your entire text box must be simple: a numbered (1-10) list of letters (a), (b) or (c). The assignment is now complete.

6. Each correct association up to 8 correct answers is granted 7 points. If you get 9 or 10 out of 10, you get a perfect score (60 pts.) on the assignment.

Submit this assignment by 11:59 p.m. (ET) on Monday of Module/Week 9.

BIOL 101

Individual Assignment 3 – 10 Discoveries in the War on Cancer

1. Virologists are modifying lentiviruses as vectors for carrying proto-oncogenes into cancer-transformed cells in culture. They are developing this virus for inserting the ras proto-oncogene directly into its correct location in the genome. The correct ras gene will already be linked to human DNA on either side of it and complexed with a recombination enzyme that will insert it into its correct location within the human genome. At the same time, the recombination enzyme will excise the defective oncogenic form of ras. The cells in culture should again come under normal hormonal control and require extra-cellular signals in order to continue dividing.

 

2. Malignant brain tumors in adults are fast-growing cancers with median survival rates of 15 months, even with aggressive treatment. Researchers have been searching for genetic “signatures” (characteristic groups of cancer-causing genes) that could help in defining the kind of brain tumor the patient has. They hope to be better able to predict the course of the disease and more accurately design the patient’s course of treatment.

 

3. Tobacco smoking is the leading cause of preventable deaths worldwide. It is a risk factor for lung cancer and several other types of cancer. Results of analysis of the entire human gene collection (the “genome”) support some previous findings that a region of human chromosome number 15 contains one or more genes that are associated with smoking intensity (the number of cigarettes smoked per day) and the closely related trait of nicotine dependency. Scanning people’s genomes for these genes will help them to determine their risk of addiction should they begin smoking tobacco.

 

4. Immunologists are working with a mutation (HER2) that is expressed on the surface of many breast, bladder, pancreatic, and ovarian cancer cells. They have made antibodies against this mutant surface protein. These antibodies have been covalently bonded to a “gene expression vector” that makes cells light up when incubated with luciferin from fire flies. The vector takes the gene for luciferin into the cancer cells. The researchers have shown that their antibody can accurately find and “light up” cancer cells. Their next step is to bond the antibody to an expression vector that carries the normal HER2 gene into mutant cancer cells.

 

5. Immunologists are investigating ways to destroy lymphocytes (white blood cells of the immune system) that have become cancerous (lymphomas). A current drug Rituximab contains antibodies that bind to the surfaces of these lymphocytes setting them up for destruction by the cancer patient’s own immune system. They are currently seeking ways to modify the antibody’s structure so that it will attract the cancer patient’s “natural killer” (NK) cells to the lymphocytes. Success of this project will bring a multi-faceted immune response against lymphomas and hasten destruction.

 

6. Biochemists have discovered a protein kinase enzyme named BRAF that is an important link in a molecular pathway that causes a cell to divide. Normally, BRAF responds to signals coming from outside the cell—signals calling for the cell to divide normally under normal conditions. But there is a mutation in BRAF enzymes that causes it activate the cell toward division continually. In this way it gives rise to melanomas and thyroid or ovarian cancers. Biochemists have also found a drug, vemurafenib, which binds selectively to mutant BRAF totally inactivating it. Cells that have inactivated BRAF undergo apoptosis—a process that leads to cell death.

 

7. Molecular biologists have taken nanoparticle-sized spheres and used them to deliver a cell-killing toxin from bee venom to tumors in mice, substantially reducing tumor growth without harming normal body tissues. Nanoparticles are known to concentrate in solid tumors because blood vessels in tumors show “enhanced permeability and retention effect” or EPR. Hence substances such as nanoparticles escape more readily from the bloodstream into tumors and the generally poor drainage of lymph from tumors further helps trap the particles in tumor tissue.

 

8. Organic chemists are exploring structural variations of the organic compound avobenzone (1-[4-Methoxyphenyl]-3-[4-tert-butylphenyl] propane-1,3-dione) for inclusion in sunblock products. Avobenzone is known for its ability to absorb a broad spectrum of ultra-violet radiations including UVB light (known to enhance the frequency of basal cell and squamous cell carcinomas [skin cancers]); and UVA rays thought to increase the frequency of melanoma cancers. New variations in the structure of avobenzone are hoped to retain the ability to absorb harmful UV radiation while having an increased stability in the presence of that radiation.

 

9. Biochemists are analyzing the many, many components of red meat (beef and pork) to determine which component, if any, will cause increased colorectal cancer rates in mice when the component is administered orally. Studies have shown that higher colorectal cancer rates in humans are associated with higher consumption rates of red meat.

 

10. Molecular biologists have developed a new sequence of human genes called an ankyrin insulator sequence. A new corrected or therapeutic gene is placed within this sequence. Its role is to create an active area on a human chromosome where the new gene can work efficiently no matter what chromosome it lands on.

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Ways to Fight Cancer

 
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