Virus Flashcards
What is the definition of a virus
A non cellular particle which is made of genetic material that infects cells of both eukaryotes and prokaryotes
what are the four shapes of a virus
polyhedral, enveloped, phage, helical
what are the three shapes of bacteria
cocci, bacilli and spirilla
describe the dna in a bacterium cell. where is it?
There is DNA/ RNA but not in the nucleus because there is no nucleus or other membrane bound organelles. It is found in nucleoid.
what are the 2 kingdoms of bacteria
archaebacteria and eubacteria
name the three archaebacteria
methanogens, halophiles and thermoacidophiles
name the three eubacteria
heterotrophs, photoautotrophs, chemoautotrophs
describe chemoautotroph
chemosynthetic molecules - make organic molecules
what does the flagellum do?
help with moving the bacteria to assist in cell movement
What are the parts of a virus?
Head and tail region. Capsid at top. Nucleic acid in the head. Tail fibers at the bottom to inject genetic material. Sheath and plug.
What are the 2 ways of infection
Attaches to surface of plasma membrane on host cell and inject genetic material while the capsid remains outside.
Capsid enters the cell and releases the nucleic acid.
What are the 2 infection cycles
Lytic and lysogenic
In the lysogenic cycle, the new viral nucleic is called…
prophage/ provirus.
Prophage in prokaryote
provirus in eukaryote
Why may the provirus become activated/triggered?
Change in temperature, pH or stress
how can viruses spread?
airborne - through coughs and sneezes
direct contact with contaminated person or surface
transfer of bodily fluids
What are examples of the first line of defence?
skin, mucus, tears, saliva
What makes up the second line of defence?
certain white blood cells like macrophages
What makes up the third line of defence?
lymphocyte and specific white blood cells that identify the pathogen as foreign and release antibodies in response
what is active immunity
when weakened strain of pathogen is injected in body to produce antibodies
what is passive immunity
injection of antibodies; short lived
what is herd immunity
vast majority of individuals in a population get vaccinated
what are ways to stop the spread of infection?
washing hands, take precaution when around infected people - wear a mask if possible.
do antibiotics work on viruses?
no because they don’t have any metabolical processes on their own.
what did alexander fleming discover and when?
he discovered penicillin in 1928
why is a cell wall important for bacteria
gives structure and support/maintains cell shape and structural integrity
why don’t bacteria overpopulate the earth? (4 reasons)
not always ideal growing conditions
may run out of nutrients/ water
poison themselves with their own waste
predators may eat them
describe binary fission and how often/ quick can it be done.
asexual reproduction. chromosome is copied and the cell grows larger and separates to produce and identical cell.
Under ideal conditions, every 20 minutes
Explain sexual reproduction in bacteria
Conjugation is the process by which one bacterium transfers genetic material to another through direct contact. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. The donor bacterium carries a DNA sequence called the fertility factor, or F-factor. The F-factor allows the donor to produce a thin, tubelike structure called a pilus, which the donor uses to contact the recipient. The pilus then draws the two bacteria together, at which time the donor bacterium transfers genetic material to the recipient bacterium. Typically, the genetic material is in the form of a plasmid, or a small, circular piece of DNA. The genetic material transferred during conjugation often provides the recipient bacterium with some sort of genetic advantage. For instance, in many cases, conjugation serves to transfer plasmids that carry antibiotic resistance genes.
