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Your friend has isolated plasma membranes and reassembled themembranes into small vesicles. Using fluorescently labeled lectin,he sees that some of his vesicles are fluorescently labeled andsome are not. Recall that lectin binds to carbohydrates.Furthermore, his labeled lectin cannot permeate membranes.

A. Which population of vesicles has a surface similar to that ofthe cell? Why?

B. How do you explain the other population of vesicles?

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Bunny Greenfelder
Bunny GreenfelderLv2
28 Sep 2019

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Related questions


Class 6: Viruses (and Cells, continued)


Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.


Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80°C (175°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organisms’ enzymes that function best ~37°C (98°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this “Central Dogma” of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotes’ ability to “fix” nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athlete’s foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid – cholesterol.
9. During retrovirus infection, a DNA copy is made of the virus’s RNA genome. A cut is made in the host cell’s DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (“70S” ribosomes) than eukaryotic cells (“80S” ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.



2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cell’s chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however they’re unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).


When you have completed the matching activity, answer these follow-up questions:
• What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
• Why are these drugs (above) safe for you to take? That is, why don’t they kill your cells?
• Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

1.1 Maria is a genetic counselor and has a son who looks very much like her. Total strangers often say “He is your little clone—he looks just like you!” She’s tempted to retort, “No he’s not! You obviously don’t know anything about genetics!” but instead just says “Thank you.”

a. Based on what you know about genetics explain why Maria’s son could not be her clone.

b. Would it be legal to for Maria to make a clone of herself? Should it be? Explain your answer in 1-2 sentences.

1.2 When I was an undergraduate, a friend of mine who knew I was working on genetics offered to pay me a tidy sum to clone his dog Mitzi, who he loved dearly, so that he would never have to be without her. Although I could have used the money, I declined.

a. If I had cloned Mitzi, would Mitzi’s clone have been identical to Mitzi in appearance and behavior?

b. If she would not have been identical, explain why not in terms of genetics and gene expression.

1.3 (2 pts) List an example of a clone that is found in nature (rather than made in agricultural practice or the lab) in each of the following categories and escribe the characteristic(s) that qualify it to be considered a clone, in 1-2 sentences.

a. Single-celled organism

b. Plant

c. Animal

1.4 Plants have been genetically modified for many different reasons, which can be loosely grouped into two categories:

To increase yield. Examples include pesticide resistance, longer shelf-life modification and drought resistance.

To directly improve human health. Examples include: increasing the nutritional value of crops, removing allergenic substances, and using crops to produce vaccines.

Find one example of a crop in each category, then answer the following questions for each. Do not use examples we will discuss in class, which are BT, Round-up ready crops and Golden Rice, or other crops modified to make beta carotene.

a.GMO plants to increase yield (3 pts)

i.Name the GMO (e.g corn) and the gene or genes that were added or changed.

ii.What benefit(s) does the gene/s confer to the crop?

iii.Is this product in commercial use today?

iv.What are the regulations on the use of this product? Does it need to be labeled? Do farmers have to have a special permit to grow it?

v.What is one concern regarding the use of this crop?

b.GMO plants to benefit human health (3 pts)

i.Name the GMO (e.g corn) and the gene or genes that were added or changed.

ii.What benefit(s) does the gene/s confer to humans?

iii.Is this product in commercial use today?

iv.What are the regulations on the use of this product? Does it need to be labeled? Do farmers have to have a special permit to grow it?

v. What is one concern regarding the use of this crop?

The Case of the Aging Surfer

Seth, a thirty-eight year-old white male of Scandinavian descent, has lived his entire life in Southern Florida. He is very concerned with maintaining a "healthy" appearance. Seth is very athletic and especially enjoys surfing. He has been surfing since the age of twelve and he started making surfboards while he was in high school. After obtaining a college degree in marketing Seth decided to start his own business making surfboards and giving surfing lessons for a local resort near his home. During a routine physical examination the physician assistant that Seth sees commented on the presence and appearance of a small growth (approximately 2-cm in diameter) above Seth's right eyebrow. This growth was shiny with a pearly border, a central ulcer and engorged surface blood vessels. The physician assistant was concerned that this might be a tumor and asked Seth a number of questions to aid in the diagnosis. Seth reported that he noticed this growth approximately six months ago but thought nothing about it since he often developed "pimples" when he was working on surfboards because of the heat and dust. Seth noticed that the growth would occasionally bleed, but he thought the bleeding most often occurred when he absently scratched above his eyebrows when he was working. Seth also reported that after bleeding the growth would "crust over" and appear to heal, but not disappear. Seth also thinks the lesion has increased in size, but he can't be certain.

The physician assistant asks Seth to come back in two days to visit with the attending physician and encourages Seth to be sure to use sunscreen whenever possible, especially when he is surfing or teaching surfing classes. Upon returning to see the physician, Seth is told that he probably has a basal cell carcinoma. This, the physician explains, is a cancer that while not benign, rarely metastasizes and grows very slowly. This type of cancer usually occurs in areas that have the greatest exposure to the sun (i.e. the face, head, and neck). While this cancer would probably not metastasize, the physician suggests surgical removal to minimize damage to any underlying tissues and a histological examination of the excised tissue to confirm the diagnosis.

Seth is concerned that if this is indeed cancer he will have to undergo radiation and/or chemotherapy and suffer from both hair loss and nausea like his mother did when she was being treated for breast cancer 10 years ago. The physician assures Seth that these treatments are not required for basal cell carcinoma and explains that this cancer usually remains localized to the specific area of the skin and does not usually spread to other tissues, so radiation and chemotherapy would not be necessary. Seth then asks why it is necessary to remove the tumor if it will not spread and is told that while the tumor does not spread to other body areas it will continue to grow and also invade deeper layers of the skin, such as the dermis, and destroy normal tissues. Seth agrees to the procedure and schedules a follow-up appointment to discuss the results of the biopsy the following week. At the follow-up appointment, Seth is told that the lesion was indeed a basal cell carcinoma. He is told that it will be important for him to try to use both sunscreens, specifically those containing para-aminobenzoic acid or PABA, and protective clothing as much as possible to minimize the effects of the ultraviolet (UV) rays of the sunlight. Seth is also told that while he should not be overly concerned, he should also pay close attention for similar lesions in the future, since a person with a single basal cell carcinoma is likely to develop additional basal cell carcinomas in the future.

http://emedicine.com/derm/topic47.htm

http://www.skincancer.org

The Case of the Aging Surfer:

Define the bold terms in the text.

How are benign and malignant tumors similar and different from each other?

Identify and briefly describe the three most common types of skin cancer and the risk to individuals who have developed each of them.

What are oncogenes and how are they believed to be related to cancer?.

Identify both the primary risk factors that Seth presents with and other risk factors that may or may not relate to Seth's case.

The procedure that Seth experiences is called the Mohs Surgery. What does it involve?

How do chemotherapy and radiation therapy act as treatments for cancer?

8) Explain why tanning booths are actually more dangerous than sunlight exposure in increasing the risk of developing some form of skin cancer.

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