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Acellular Microbes Viruses, Viroids, and Prions Explained
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May 1, 2025
Acellular Microbes Viruses, Viroids, and Prions Explained Website: https://biologynotesonline.com/ Facebook: https://www.facebook.com/biologynotesonline Instagram: https://www.instagram.com/biologynotesonline/?hl=en In this informative video, we delve into the fascinating world of acellular microbes, focusing on viruses, viroids, and prions. Discover the unique characteristics that differentiate these entities from traditional cellular life forms. We will explore their structures, replication mechanisms, and the roles they play in various biological processes and diseases. Whether you're a student, researcher, or simply curious about microbiology, this video provides a comprehensive overview of these intriguing acellular organisms. Join us as we unravel the complexities of viruses, viroids, and prions, and their impact on health and the environment. #Microbiology #AcellularLife #Viruses
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0:00
in the world of microbiology a unique
0:02
class of infectious agents exists that
0:04
defies traditional classification a
0:07
cellular microorganisms are infectious
0:09
agents that lack a cellular
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structure unlike bacteria fungi and
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parasites a cellular microorganisms lack
0:17
the fundamental components of cells they
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don't have cell membranes organels or
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the ability to metabolize nutrients this
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makes them fundamentally different from
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typical microorganisms
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there are three main types of aellular
0:31
microorganisms viruses vyroids and pions
0:35
viruses consist of genetic material
0:36
either DNA or RNA encased in a protein
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coat called a capsid some viruses also
0:41
have an outer envelope vyroids are much
0:44
simpler they are small circular RNA
0:47
molecules without a protein coat they
0:49
primarily infect plants pions are the
0:52
most unusual they are simply misfolded
0:54
proteins without any genetic material at
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all yet they can cause fatal
0:58
neurodeenerative
1:00
diseases what makes a cellular
1:02
microorganisms unique is their complete
1:05
dependence on host cells they cannot
1:07
metabolize nutrients or reproduce on
1:09
their own instead they must hijack the
1:12
machinery of a host cell after using the
1:15
host's resources to replicate new
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infectious particles are released often
1:20
destroying the host cell in the process
1:23
to summarize a cellular microorganisms
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have five key characteristics they lack
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cellular structure cannot reproduce
1:30
independently cannot metabolize rely
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completely on host machinery and include
1:34
viruses vyroids and
1:38
pions a cellular microorganisms cannot
1:41
replicate independently due to their
1:43
fundamental lack of cellular machinery
1:46
unlike cellular organisms viruses
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vyroids and pions must hijack the host
1:50
cell's molecular machinery to
1:54
reproduce viruses are composed of
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genetic material either DNA or RNA
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surrounded by a protein coat the virus
2:01
replication cycle involves several key
2:04
steps first the virus attaches to
2:06
specific receptors on the host cell
2:08
surface and enters the cell inside the
2:11
cell the viral genetic material is
2:13
released and uses the host's enzymes and
2:15
resources to replicate its genome the
2:18
host cell's ribosomes then synthesize
2:20
viral proteins using the instructions
2:22
from the viral genome these viral
2:25
components then assemble into new virus
2:27
particles inside the cell finally the
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new viruses are released from the cell
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often causing cell lis or death and can
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go on to infect other cells
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vyroids are significantly simpler than
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viruses they consist of a small circular
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RNA molecule without a protein coat
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vyroid replication follows several
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distinct steps vyroids enter plant cells
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through mechanical wounds or during
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plant propagation once inside they
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migrate to the nucleus where plant RNA
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polymerases recognize their structure
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unlike viruses vyroids do not encode any
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proteins instead they hijack the plant's
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RNA polymerase to catalyze a rolling
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circle mechanism of replication the
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plant's own RNA processing enzymes then
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cleave the long RNA strands into
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individual vyroid genomes and circle
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them these newly formed vyroids can move
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through the plant's vascular system
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spreading the infection to other parts
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of the
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plant pions represent a unique mechanism
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of replication that does not involve
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genetic material at all unlike viruses
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and vyroids pions replicate through a
3:34
process of protein misfolding and
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aggregation first a misfolded pryion
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protein enters the cell or forms
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spontaneously through mutation this
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abnormal protein comes into contact with
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normally folded proteins of the same
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type the pryion then induces the normal
3:50
protein to change its confirmation and
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become misfolded as well this process
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creates a cascading effect where each
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misfolded protein can convert more
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normal proteins eventually these
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misfolded proteins aggregate into
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insoluble amaloid fibbrals that disrupt
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cellular function and lead to
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neurodeeneration to summarize allular
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microorganisms depend on host cells but
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each has evolved a unique strategy for
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replication despite their structural and
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functional differences viruses vyroids
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and pions all share the fundamental
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characteristic of being entirely
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dependent on host cells for their
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propagation hiv the human immuno
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deficiency virus is a retrovirus with an
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RNA genome it primarily attacks and
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destroys CD4 plus T cells of the immune
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system leading to AIDS if left untreated
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hiv is transmitted through direct
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contact with bodily fluids such as blood
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semen or breast
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milk the influenza virus has a segmented
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RNA genome that contributes to its high
5:00
mutation rate a phenomenon known as
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antigenic drift this explains why we
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need new flu vaccines each year
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influenza causes seasonal flu epidemics
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and is primarily transmitted through
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respiratory droplets when an infected
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person coughs or sneezes
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sars KV2 is a corona virus with an RNA
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genome and distinctive spike proteins
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that give the virus its crown-like
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appearance it emerged in late 2019 and
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caused the global CO 19 pandemic like
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influenza it spreads primarily through
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respiratory droplets and
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aerosols these three viruses have had
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significant global health impacts hiv
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continues to affect millions worldwide
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with approximately 680,000 annual AIDS
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related deaths seasonal influenza claims
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between 290,000 and 650,000 lives each
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year sars KV2 has caused approximately 7
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million deaths since the pandemic
6:03
began vyroids are small circular RNA
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pathogens that primarily affect plants
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unlike viruses they lack a protein coat
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their structure consists simply of a
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circular RNA molecule that can fold into
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a complex shape the potato spindle tuber
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vyroid discovered in 1971 causes a
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serious disease in potato plants
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infected potatoes develop an elongated
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spindle shape compared to healthy round
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potatoes symptoms include elongated
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tubers stunted plant growth and
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significantly reduced crop yields of up
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to 40%
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the tomato plant macho vyroid affects
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tomato plants worldwide infected tomato
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plants show distinct differences from
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healthy plants with notable yellowing
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and reduced size symptoms include loss
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of chlorophyll stunted growth reduced
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fruit size and leaf
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deformation the avocado sunblot vyroid
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affects the quality and quantity of
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avocado production worldwide infected
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avocados develop characteristic yellow
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or red streaking on the skin called
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sunlot symptoms include distinctive
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yellow streaking smaller deformed fruits
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and reduced yields of 15 to
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30% these vyroid infections collectively
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result in millions of dollars in crop
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losses annually affecting agricultural
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economies worldwide
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the classification of living organisms
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follows the three domain system bacteria
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archa and ukaria a cellular
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microorganisms like viruses vyroids and
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pions don't fit into this classification
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system these entities are excluded from
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the tree of life because they lack
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cellular structure and cannot perform
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independent life processes their
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classification as living or non-living
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entities remains a matter of scientific
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debate scientists continue to study
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these entities to better understand
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their place in biology and the broader
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context of what we define as life