Viruses

Question 1

Are viruses living or non-living

Answer 1

non-living

Question 2

What do all viruses require to survive

Answer 2

A host

Question 3

What are DNA and RNA and what are they made out of.

Answer 3

DNA and RNA are “Nucleic Acids” The building block of these nucleic acids are “nucleotides”, which consist of a phosphate (P), sugar (S) and a base (B).

Question 4

What is the function of DNA and RNA in a bacterial cell

Answer 4

hold the key to genetic information for keeping viruses functioning and allowing for reproduction.

Question 5

What are the two differences between DNA and RNA

Answer 5

RNA is single-stranded; DNA is double-stranded and the strands form a “double helix”
Both DNA and RNA possess four different bases; DNA has ATGC, and RNA has AUGC.

Question 6

Convert from DNA to RNA:
A G T T G A C G A T G

Answer 6

U C A A C U G C U A G

Question 7

What do viruses do with their genetic information that can be detrimental to us?

Answer 7

The virus inject its DNA or RNA into our cells and uses our cell’s DNA-making proteins and techniques to create more virus cells.

Question 8

What are the two steps of protein synthesis?

Answer 8

Transcription
Translation

Question 9

What are proteins made up of and what determines their shape/function?

Answer 9

Proteins are molecules made up of individual units called amino acids. The sequence of amino acids dictates the shape of the resulting protein and therefore the function

Question 10

What are the two main functions of protein. Name them

Answer 10

Structural and Catalysts

Question 11

Explain the structural function of proteins

Answer 11

Proteins can fit together and become part of a structure, like the capsid of a virus, or your hair and fingernails.

Question 12

Explain the catalyst function of proteins

Answer 12

Proteins can speed up chemical reactions. Their shape allows chemicals to fit into their “active sites” like a lock and key. From there, the chemicals will be bonded together, or torn apart. These kinds of proteins are called enzymes.

Question 13

Where does transcription occur?

Answer 13

in the nucleus

Question 14

where does translation occur

Answer 14

in the ribosomes

Question 15

Explain what occurs in transcription

Answer 15

The DNA needs to be converted into RNA (using the DNA to RNA base pairing rule

Question 16

Explain what occurs in translation

Answer 16

The strand of RNA leaves the nucleus and joins a ribosome. It is now known as a “messenger RNA”, or mRNA. The cell “reads” the mRNA in groups of 3, called CODONS, and a transfer RNA, tRNA, with a corresponding ANTICODON, delivers its specific amino acid to the ribosome. This process continues, and the protein gets longer. Translation stops when a “stop” codon is reached. The resulting protein may be structural or an enzyme.

Question 17

What are the three types of viruses

Answer 17

DNA, RNA, and Retrovirus

Question 18

Explain what would make a virus a DNA virus

Answer 18

Contain DNA which will be the starting point of protein synthesis

Question 19

Explain what would make a virus a RNA virus

Answer 19

Contain RNA, which means the first step of protein synthesis, transcription, is “skipped” and the RNA enters translation

Question 20

Explain what would make a virus a Retrovirus

Answer 20

Contain RNA and an enzyme called “reverse transcriptase”. Reverse transcriptase converts the viral RNA “backwards” into DNA. Then protein synthesis starts at that point – the beginning.

Question 21

What type of virus is most unstable/dangerous and why?

Answer 21

Viruses that contain RNA are more unstable as they mutate, or change the order of their bases, more often than DNA viruses do. As a result, treatment for these types of viruses may need to change more frequently, and it is more difficult to develop vaccines because there can be many different strains.

Question 22

What are the lytic/lysogenic cycles?

Answer 22

how viruses behave and reproduce in your cells in order to cause disease.

Question 23

Explain the steps of the lytic cycle

Answer 23

1. Virus attaches to cell and inserts DNA
2. Viral DNA forms a circle inside cell (at this stage the cell will either go lytic or lysogenic)
3. New viral DNA and proteins are produced and assembled
4. The cell burst, releasing more viral DNA and proteins

Question 24

Explain the steps of the lysogenic cycle

Answer 24

1. Virus attached to cell and inserts DNA
2. Viral DNA forms a circle inside cell (at this stage the cell with either go lytic or lysogenic)
3. Viral DNA inserts itself into bacterial chromosome
4. Bacterium reproduces normally, replicating viral DNA with each cell division. Cell and viral DNA are reproduced many times
5. Occasionally, the viral DNA separates from the bacterial chromosome, initiating a lytic cycle when enough viral DNA has been replicated.

Question 25

What determines if a cell will go lytic or lysogenic?

Answer 25

The relative virulence, or ability to cause disease. Viruses can be very virulent and cause disease symptoms quickly and all at once, like a cold (lytic cycle) Or viruses can be temperate and remain in hiding and cause bouts of disease symptoms more slowly and over longer periods of times, like HIV or Herpes (lysogenic cycle).

Question 26

How is immunity achieved?

Answer 26

Immunity is achieved when a pathogen enters a host, BUT that host fights it off before illness occurs.

Question 27

What are humans 3 lines of defense?

Answer 27

1. skins, acids, mucus membranes. 2. white blood cells, inflammation, fever 3. specific, system-wide, whole-body fight that involves specialized white blood cells called B and T cells.

Question 28

Which line of defence involves immunity?

Answer 28

the THIRD line of defence

Question 29

Why does the second line of defence involve fever? What does a fever do to the virus?

Answer 29

Once the phagocytes have been activated, a chemical called interleukin-1, IL-1, is released by the phagocytes and travels to the hypothalamus and resets it, increasing your temperature and causing fever. Fever slows the reproduction rate of the pathogens, and higher temperatures cause a faster immune response to occur.

Question 30

Where are B-cells and T-cells produced?

Answer 30

These cells are manufactured in the lymphatics system

Question 31

What is the lymphatic system?

Answer 31

The lymphatics system consists of a network of lymph vessels that contain a fluid called “lymph”. Sometimes these vessels widen into “nodes”. When a localized infection occurs, nearby nodes swell, like tonsils in the throat.

Question 32

Where do B-cells and T-cells mature?

Answer 32

B cells are made and mature in the Bone marrow, and are then sent into the blood. T cells are also made in the bone marrow, but they migrate to the Thymus to mature before entering the blood stream

Question 33

What is an antigen? What is an antibody? Explain the relationship between the two.

Answer 33

Antigens are any part of an invader that triggers the production of antibodies. Antibodies are made by people in response to an antigen. They are Y-shaped proteins whose upper “tips” differ in their shapes. When antigens trigger the formation of antibodies, only those antibodies with the corresponding shape will be produced.

Question 34

What is the cell-mediated response and which cells does it use?

Answer 34

The Cell-Mediated response causes T cells to destroy body cells that have already been invaded by the pathogen

Question 35

What is the humoural response and which cells does it use?

Answer 35

The Humoral response causes B cells to produce antibodies which then attach to the antigens on the pathogen, rendering them useless.

Question 36

Why does the second exposure to the same antigen evokes a faster response with a larger concentration of antibodies.

Answer 36

This second faster response is due to the presence of the memory B and memory T cells

Question 37

What are the two types of immunity

Answer 37

Innate (inborn, genetic factors), Acquired (as human progresses through life)

Question 38

What are the two types of acquired immunity and what do they mean

Answer 38

Active (own anti-bodies) and Passive (ready-made antibodies)

Question 39

What are the two types of active immunity and how can you get them

Answer 39

Natural (exposure to infectious agents), Articfial immunization (vaccines)

Question 40

What are two types of passive immunity and how can you get them?

Answer 40

Natural (maternal antibodies via breastmilk or placenta) or Passive (ready-made antibodies vaccines)

Question 41

What does the hygiene hypothesis state?

Answer 41

hygiene hypothesis states that early childhood exposure to particular microorganisms protects against allergic diseases by contributing to the development of the immune system. Therefore a lack of exposure due to increased hygiene is thought to lead to defects in the establishment of immune tolerance.