BIOLOGY 305 Lecture Notes - Lecture 17: Multinucleate, Blastula, Plasmid

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21 Jul 2016

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All organisms start as a single fertilized cell. Through mitosis, the cell can become an organism. Move the cells around and change the cells around for proper development. It is a given that all cells start with the same type of dna. Totipotency means that a cell can give rise to any other type of cell that is found in the body. It turns out that cells don"t stay in this state forever. They lose their ability to become any other cell. After a while they may become pluripotent (make several kinds of cells but not all) Eventually, they become determined meaning that they can only make that type of cell. It would be good to know what happens there. If we could control this, we can regenerate more organs/tissues. This is the promise of stem cell research. We know that determination and differentiation are the result of differential gene expression.

Related Questions

Below is a paragraph describing HIV infection as they relate to the progress of infection. Please help choose the correct answer in each parentheses.

HIV initially infects (CD4+, or CD8+, or B) cells. These are helper T cells that activate (CD4+ or ,CD8+ or, B) cytotoxic T cells and (CD4+, or CD8+, or B) cells which produce antibodies. If HIV kills (CD4+, or CD8+) T cells then they cannot to do their job of activating these cells thus causing HIV infected people to be immunocompromised. Sometimes HIV infected people enter a latency period where the virus is inactive. This latency period can last for several years. During latency HIV (DNA, or RNA) becomes integrated into the (CD4+ or CD8+, or B) host cells genome and stops producing viral HIV RNA and new HIV virions. However, for some unknown reason, HIV comes out of dormancy and the viral (RNA, or DNA ) that was integrated in the (CD4+ , or CD8+,) T cell genome begins to transcribe more viral (DNA , or RNA) to make more viral (DNA, or RNA) using the host cells machinery. The viral (DNA, or RNA) then gets translated by host cell ribosomes to make viral proteins that eventually become packaged into new HIV virions. Consequently, after the latency period HIV becomes activated in the host cell. These cells present HIV antigen on their cell surface and alert (CD8+ or CD4+ or B) cells to kill them. As they are killed the infected (CD4+, or CD8+, or B) cells release the HIV virions into the blood stream to infect other (CD4+ or CD8+) cells such as macrophages and dendritic cells. This explains why after latency we see (CD4+, or CD8+) T cells continue to decrease while at the same time viral (DNA, or RNA) levels increase.

Based on your answers to the fill in paragraph, which statement is true?

A. Once active in CD8+ T cells, HIV can now replicate with impunity and infect other cells which explains the increase in HIV RNA after latency.

B. The increase in active HIV after latency accounts for why HIV can remain dormant for years after the initial infection.

C. CD4+ levels stabilize after the latency period and explain why there is little increase in HIV RNA levels.

D. Opportunist infections can occur after HIV latency because there are very few helper T cells to left to activate cytotoxic T cells and B cells to mount an immune response.

1. Asbestosis is a disease that results in damage to the lungsbecause (there may be more than one answer)

a. the asbestos gets broken down by the lysosomes

b. the asbestos gets broken down by the lysosomes

c. the lysosomes that absorb the asbestos release enzymes thatkill the lung tissue cells

d. the lung tissue becomes scarred and can nolonger function tobring oxygen into the blood

2. Which of the phases of cellular respiration breaks down theglucose molecule?

a. glycolysis

b. transition reaction

c. citric acid cycle

d. electron transport chain

3. Which of the following is NOT a function of the plasmamembrane?

a. allows all substances to enter the cell

b. helps bind cells to eachother so that they can form tissuesand organs

c. allows the cell to recognize other cells

d. allows cells to "talk" to eachother

4. Which of the following mechanisms of transport across thecell requires energy?

a. osmosis

b. endocytosis

c. facilitated diffusion

d. active transport

5. Which of the following organelles acts as the "powerhouse" ofthe cell, i.e. it produces the cell's energy.

a. nucleus

b. mitochondria

c. smooth endoplasmic reticulum

d. rough endoplasmic reticulum

6. Figure 3.9 in your textbook demonstrates what happens to ared blood cell when it is put into varying solutions. The bags inthe beakers represent a single red blood cell.

What happens to a red blood cell when it is put into ahypertonic solution?

a. stays the same and is fully functional

b. shrinks and no longer functions the way it's supposed to

c. gets larger and no longer functions the way it's supposedto

d. the shape stays the same but the red blood cell is no longerfunctional

7. Which of the following real-life situations would result inthe blood (note that this is referring to the liquid part of theblood, not the blood cells - the accurate name for this wouldactually be "blood plasma") becoming too hypotonic?

a. getting stranded in the middle of a dessert and becomingseverely dehydrated

b. drinking gatorade to replenish fluids during a basketballgame

c. drinking too much water so that your body can't get rid ofthe water quickly enough to maintain the appropriate blood plasmatonicity

d. being stranded in the middle of the ocean, drinking the saltyocean water

8. The golgi complex acts as the "UPS" of the cell - itprocesses and packages materials and sends them to theirdestinations.

True

False

9. The lysosome acts as the "stomach" of the cell; it digestsparticles that are no longer needed in the cell or have been takenup into the cell to be broken down.

True

False

10. We need oxygen to survive because oxygen is needed to breakdown glucose to form ATP. When we are deprived of oxygen, our cellssuddenly stop producing ATP and we can only survive for a fewminutes with whatever ATP remains in our cells.

True

False

tancockroach913

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 ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°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 âCentral Dogmaâ 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 prokaryotesâ ability to âfixâ 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 athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs 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 (â70Sâ ribosomes) than eukaryotic cells (â80Sâ 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 cellâs 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 theyâre 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:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ 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?

BIOLOGY 305 Lecture Notes - Lecture 17: Multinucleate, Blastula, Plasmid

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