Bio 106 - Exam 3 - Chapter 27

Front 1

Are viruses dead or alive?

Back 1

Neither, they are not considered organisms.

Front 2

What are viruses?

Back 2

Oligate, intracellular parasites. considered particles or agents.

Front 3

What are viruses made up of?

Back 3

Viruses are made up of a core of nucleic acid surrounded by a protein.

Front 4

Why aren't viruses given scientific names and why are there no species of viruses?

Back 4

Viruses are considered particles or agents.

Front 5

Is the nucleic acid of the core of viruses DNA or RNA?

Back 5

It can be either.

Front 6

What is the genome of a virus?

Back 6

The genome is the core of nucleic acid.

Front 7

What is the protein that surrounds the nucleic acid of a virus called?

Back 7

Capsid is the protein that surrounds the nucleic acid of a virus.

Front 8

Why are viruses not considered organisms?

Back 8

Viruses are not cells, not made up of cells, can't make own ATP, amino acids, or nucleic acids, can't carry out transcription and translation independently, lack cellular structure, lack plasma membrane, and lack independent metabolism.

Front 9

What can't viruses make by themselves?

Back 9

Viruses can't make their own ATP, amino acids, or nucleic acids.

Front 10

What can't viruses carry out independently?

Back 10

Viruses can't carry out transcription and translation independently.

Front 11

What do viruses lack?

Back 11

Viruses lack cellular structure, plasma membrane, and independent metabolism.

Front 12

Is the hereditary material of viruses single stranded or double stranded?

Back 12

It can be either.

Front 13

Is the hereditary material of organisms single stranded or double stranded?

Back 13

Always made of DNA, so always double stranded.

Front 14

Do organisms have a plasma membrane present?

Back 14

Yes, organisms have a plasma membrane present.

Front 15

Can viruses carry out transciption independently and why?

Back 15

No, because even if viral polymerase is present, transcription of viral genome requires use of ATP and nucleotides provided by host cell.

Front 16

Do viruses have metabolic capabilities?

Back 16

Virtually none compared to the extensive metabolic capabilities of organisms.

Front 17

What type of cells can viruses infect?

Back 17

Viruses can infect both prokaryotic and eukaryotic cells.

Front 18

What are examples of viral diseases?

Back 18

Chicken pox, small pox, mononucleosis, and measles.

Front 19

Which parts of your body can viruses infect?

Back 19

Viruses can infect all aspects of the human body.

Front 20

What is virology?

Back 20

Virology is the study of viruses.

Front 21

What are the goals of virology?

Back 21

To describe viral diversity, develop vaccines, and develop antiviral drugs.

Front 22

What is the difference between vaccines and antiviral drugs?

Back 22

Vaccines help the infected hosts fight disease, while antiviral drugs inhibit virus reproduction inside a host.

Front 23

What are the steps to developing vaccines?

Back 23

Isolate virus in question, analyze morphological traits, understand replication cycle, and develop the vaccine.

Front 24

When analysing morphological traits of viruses in order to develop a vaccine, what part of the virus is focused on?

Back 24

When analysing morphological traits of viruses in order to develop a vaccine, the capsid is focused on..

Front 25

What are antigens?

Back 25

Antigens are usually protein components of a virus capsid or envelop.

Front 26

After viral antigens are introduced into the body, what occurs?

Back 26

After viral antigens are introduced into the body, the antigens bind to receptors on certain immune system cells.

Front 27

After the antigens bind to receptors on certain immune system cells, what occurs?

Back 27

After the antigens bind to receptors on certain immune system cells, these cells stimulate other immune system cells to produce antibodies to the virus.

Front 28

How long can cells that produce specific antibodies remain active?

Back 28

The cells that produce specific antibodies remain active for years or decades.

Front 29

What happens if a host organism is exposed to virus particles after having already had the vaccination?

Back 29

If the host organism is exposed to actual virus particles after already having received a vaccination for it, the antibody-producing cells are activated.

Front 30

What happens after antibody-producing cells are activated?

Back 30

After antibody producing cells are activated, virus particles become coated with antibodies.

Front 31

What happens to viruses that are coated with antibodies?

Back 31

Viruses that are coated with antibodies are destroyed by immune system cells.

Front 32

Are vaccines used as vectors/transporters of information in immunotherapy?

Back 32

Yes, vaccines are used in immunotherapy as vectors or transporters of information.

Front 33

What is immunotherapy?

Back 33

Immunotherapy is treatment that stimulates the immune system's ability to fight disease.

Front 34

What is an example of the use of vaccines in immunotherapy and an important area of study in immunotherapy?

Back 34

An example of the use of vaccines in immunotherapy is with metastatic melanoma (a form of skin cancer that can spread to other parts of the body).

Front 35

Can viruses be used to trigger the body to fight not only viral diseases, but other diseases as well?

Back 35

Yes, viruses be used to trigger the body to fight not only viral diseases, but other diseases as well.

Front 36

In the example of metastatic melanoma for the use of vaccines in immunotherapy, what was the local effect of OncoVEX?

Back 36

OncoVEX is a virus that invades both healthy and cancerous cells, but doesn't affect healthy cells and destroys tumor cells.

Front 37

In the example of metastatic melanoma for the use of vaccines in immunotherapy, what was the systemic effect of OncoVEX?

Back 37

As the virus is replication in the tumor cells, it makes a special factor that has the ability to find other tumor cells. The immune system then destroys those cells.

Front 38

What are the two virus structures?

Back 38

The two virus structures are helical and icosahedral.

Front 39

There's a figure with four examples of virus shapes. One is cylindrical, one looks like a spikey diamond, one looks like it can crawl around, one looks like a U inside a ball. Explain.

Back 39

The plant virus has a helical capsid. The animal virus (adenovirus) has an icosahedral capsid. The bacterial virus has an icosahedral head and a helical tail. The influenza animal virus has a helical capsid within an envelope.

Front 40

Explain the variation in viral genome (nucleic acids of virus).

Back 40

There exists both RNA and DNA genomes, which are both problematic in causing sicknesses.

Front 41

Viruses infect cells from all 3 domains. What are the 3 domains?

Back 41

Viruses are effective in finding hosts and infect the 3 domains: bacteria, archaea, and eukarya.

Front 42

What is a bacteriophage?

Back 42

Bacteriophases are bacterial viruses that infect bacteria.

Front 43

What are the two cycles of bacteriophages?

Back 43

The two cycles of bacterial viruses that infect bacteria are lytic and lysogenic.

Front 44

What is the lytic cycle?

Back 44

The lytic cycle is when the viruses lyses the infected host cell.

Front 45

What is the lysogenic cycle?

Back 45

The lysogenic cycle is when a DNA segment from the virus (prophage) integrates with host cell DNA. The host cell then replicates with the viral DNA in it. Later, the viral genome will become activated, form viral particles, and exit the cell.

Front 46

What are the 5 steps of the lytic cycle?

Back 46

Attachment, penetration, synthesis, assembly, and release.

Front 47

Describe the 5 steps of the lytic cycle.

Back 47

The virus attaches itself to the cell wall. The viral DNA is injected into the cell. The viral genome directs the bacterial cell to synthesize protein and nucleic acid needed to make new viral particles. There is spontaneous assembly of capsid and enzyme to insert DNA. And the lysis of the cell releases the bacteriophages.

Front 48

What is the type of bacteriophage cycle that only affects one cell at a time? What is the other type that affects multiple cells through replication?

Back 48

The lytic cycle only affects one cell at a time. Lysogenic cycle affects all cells involved in the host's replication.

Front 49

Why are there two different cycles?

Back 49

There are two different cycles for different conditions. During bad conditions, the virus stays dormant in the lysogenic cycle. The lytic cycle is faster and more short-term.

Front 50

What does cell stress cause duing the lysogenic cycle?

Back 50

Cell stress causes the reproduction of lysogenic bacteria by triggering transcription and translation.

Front 51

Where does the lysogenic cycle come into the lytic cycle? In other words, after what step in the lytic cycle could a bacteriophage enter the lysogenic cycle and at what step does it re-enter the lytic cycle?

Back 51

After penetration in the lytic cycle, the bacteriophage could enter the integration step of the lysogenic cycle. Then after the induction step in the lysogenic cycle, it can enter the synthesis step of the lytic cycle.

Front 52

What are the 9 steps of the lysogenic cycle?

Back 52

Attachment, penetration, integration, propagation, cell stress, induction, synthesis, assembly, release.

Front 53

Describe the integration step of the lysogenic cycle.

Back 53

During integration, the viral genome is integrated into the bacterial genome, which leads to prophage.

Front 54

Describe the propagation step of the lysogenic cycle.

Back 54

It's the replication of the viral genome along with the bacterial genome it has become a part of; the reproduction of lysogenic bacteria

Front 55

Describe the induction step of the lysogenic cycle.

Back 55

Induction is when the prophage exits the bacterial chromosome and the viral genes are expressed.

Front 56

What is AIDS caused by?

Back 56

It's caused by the human immunodeficiency virus (HIV).

Front 57

What does HIV attack?

Back 57

HIV attacks CD4+ cells, which are primarily T-helper ceells.

Front 58

What happens to AIDS patients?

Back 58

AIDS patients die of infections that a healthy person could fight off.

Front 59

HIV affects a cell in which domain?

Back 59

HIV is a eukaryote virus.

Front 60

Which continent has the highest incidents of AIDS?

Back 60

Africa has the highest incidents of AIDS, but it affects people on all continents.

Front 61

Describe the two phases that occur before AIDS.

Back 61

During the acute phase (first 9 weeks), there is a dramatic drop in helper T cells. Then it stabilizes during the chronic phase. The number of helper T cells continues until the onset of AIDS, which is marked by a certain number of helper T cells.

Front 62

What kind of structure does HIV have?

Back 62

There's an envelop that surrounds the capsid for HIV.

Front 63

How does the virus bind to helper T cells?

Back 63

The glycoprotein markers (gp120) on the virus surface binds to cell surface marker protein CD4 on CD4+ cells.

Front 64

What happens after gp120 binds to CD4 (cell-surface marker protein)?

Back 64

After gp120 binds to CD4, conformational changes occur that allow the virus to bind to a co-receptor (CCR5), which pulls HIV across the cell membrane and the viral contents enter the cell by endocytosis.

Front 65

What happens in the cytoplasm of a CD4+ cell after the HIV has entered through endocytosis?

Back 65

In the cytoplasm, reverse transcriptase synthesizes complementary DNA (cDNA) from viral RNA. The viral DNA then enters the nucleus where a viral enzyme incorporates viral DNA into the host cells' DNA.

Front 66

What happens after dormancy in a CD4+ cell after the HIV has entered through endocytosis?

Back 66

After dormancy, the viral DNA directs the host cell to make copies of the viral DNA and the virus exits the cell by budding.

Front 67

Explain viral targets for therapeutic drugs.

Back 67

Companies are trying to develop drugs that stop the HIV infecting process at one or more points (attachment, entry, replication, and assembly).