Microbiology: Viruses and Subviral particles Flashcards
What kind of characteristics do gut bacteria have
Obligate anaerobes (do not require O2)
conjugation can occur between bacterial cells of what status ?
from F+ to F-
What mechanism do bacteria use to reproduce ?
Binary fission
what viral component is only derived from animal cells ?
Envelope
What kind of RNA does RNA Polymerase I transcribe?
rRNA
Which polymerase can alter chaperone proteins?
RNA polymerase II
What happens during the proviral stage of a virus?
During the proviral stage, the viral genome is integrated with the host genome and passive replication of genome occurs.
What is the use of ELISA (Enzyme-linked immunoabsorbent Assay) ?
ELISA: are the quickest and easiest way to test for the presence of an antibody in a patient’s serum
What occurs during provirus excision ?
When the provirus leaves the host genome (excises), it can leave behind some viral DNA, or it can take some extra host DNA, altering the viral genome.
What aspect of retroviruses allows them to develop drug resistance so readily ?
-Reliance of reverse transcriptase
Reverse transcriptase (RT) is also known as( RNA-dependant DNA polymerase)
** RT does not have any proofreading mechanism. Thus, many errors occur during the creation of DNA from the viral RNA
this allows for slight variations in protein structure in viable viruses, rendering anti-retroviral drugs ineffective. **
What are the main goals of vaccines?
(1) the vaccine must not cause the disease it is trying to protect against,
(2) the vaccine must be effective in protecting the individual against the disease.
Explain why RNA genomes are smaller than DNA genomes
RNA genomes are smaller b/c RNA polymerases cannot proofread, while DNA polymerases can.
Hence it is better to keep RNA genome small, and incorporate fewer errors
What stage of virus can antibodies block ?
At the INFECTION stage, the virus is still extracellular, so this is the stage at which antibodies are effective
What stages can antibodies not block in viral process?
intracellular stages: Viral replication, release of new particles, and synthesis of new particles
Antibodies are found in the plasma and extracellular fluids and are not available to the intracellular environment.
Therefore, any process that occurs intracellularly cannot be blocked by antibodies.
Do viruses have translation machinery?
NO they do not have translation machinery and must borrow form their host cell
Which part of proteins is most accessible to antibodies ?
The glycosylated part since antibodies are located on extracellular side of protein and that part is glycosylated
Differentiate between obligate anaerobe and tolerant anaerobe
obligate anaerobe: bacteria will only grow in Absence of oxygen
tolerant anaerobe: while bacteria do NOT use oxygen, they can still grow in presence of oxygen
What occurs in bacterial conjugation ?
Conjugation occurs when an F+ “male” bacterium builds a conjugation bridge to an F– “female” bacterium in order to transfer DNA from male to female.
- Often this is just plasmid DNA (the F plasmid), but bacterial genome can also be used.
- At the end of conjugation, the F– “female”, having received the F plasmid, is now an F+ “male” (F- turns into F+ )
What is an Autotroph?
An organism that can make its own food using carbon dioxide, water or the chemicals
What are exotoxins ?
Exotoxins are toxic substances that are secreted by both Gram-negative (thin cell wall) and Gram-positive bacteria (thick cell wall), and are often very important factors in infection.
Differentiate between Gram negative and gram positive bacteria ?
Gram positive (thick peptidogylcan cell wall) stain purple
Gram negative: thin cell wall (stain pink) have outer and inner membrane
How does methicillin function ?
It is true that methicillin functions to inhibit the transpeptidase enzyme used by bacteria to cross-link the peptides in the cell wall.
differentiate between prokaryotic and eukaryotic cells
-Eukaryotic flagella are constructed out of microtubules in a “9 + 2” arrangement, whereas prokaryotic flagella are built out of a bacterial protein called flagellin, organized in to a base, hook, and filament. -Prokaryotic cell walls are constructed out of peptidoglycan, whereas eukaryotes with a cell wall utilize other carbohydrates, such as cellulose in plants or chitin in fungi. -Prokaryotes have smaller 70S ribosomes whereas eukaryotes have 80S ribosomes.
