VIRUS : BIOLOGI KELAS 10 SMA

Hello

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Hello kids, how are you,

hopefully you are always healthy, see you

again on the Sigma smartstudy learning channel.

Still with Kak Febri in

this video we will discuss the

virus material, namely biology material for grade

10, but before we start learning,

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so we can learn together on

this channel, the

word virus comes from the word

virion Sirion is Latin,

meaning itself is poison, the discovery of

viruses developed from time to time,

starting from

1883 to

1935, the development of research on

viruses began with Adolf Mayer, a

German scientist in

1883 who studied diseases in

tobacco, many tobacco leaves

had yellow spots, then the

tobacco leaves with yellow spots were

extracted and the leaf extract was

sprayed on

other healthy tobacco plants, then after

spraying it turned out that the

healthy tobacco had yellow spots, which

also means mosaic disease or

yellow spots can

transmitted and after being seen under a

microscope nothing was seen then

it was concluded that the disease

was caused by bacteria that were so

small that they were invisible this

crosscoop was then continued by

dmitri ivanovsky a scientist from

Russia in

1892 who conducted the same experiment

as Mayer the difference was ivanovsky filtered the

leaf extract Nen

bacterial filter filter or the result of filtering the

leaf extract was

sprayed onto healthy tobacco plants

and then yellow spots also appeared

lewat poloski concluded there were two

possibilities namely the disease

was caused by microbes that were

smaller than bacteria or the microbes

had substances or toxins that could

penetrate the tissue

then ivanovski's research

was continued by Martinus beijerinck

a scientist from the Netherlands in

1898 bearing repeatedly sprayed the

filtrate of healthy plant leaf extract

it turned out that the disease was continuously

contagious meaning the agent causing the disease

could continue to reproduce itself

and after going through various

experiments it turned out that the agent causing the

disease did not die because of

alcohol and could not be grown in

artificial growth media then bearing

named the agent as a

pathogenic living fluid or

contagium fluidum and in the end the

research on the mosaic disease

on tobacco leaves was

perfected by wendell Meredith

Stanley, an American scientist

in

1935, how Stanley isolated and

crystallized the tobacco mosaic virus

or tobacco mosaic virus, then Stanley

concluded that viruses are different from

bacteria because they can be crystallized and

only develop in living cells.

Now, pay attention to the leftmost picture,

which is a picture of tobacco leaves that

have yellow spots or

mosaic disease. Next is a picture of the

TMV virus seen under an

electron microscope. And the rightmost

is an illustration of the TMV virus that has been

perfected.

So, is the virus actually a

living or non-living thing? So, if

we conclude, a virus is a

metaorganism or transitional organism

between inanimate objects and

living things. This is because viruses

have several characteristics. First, they

do not have organelles so they

cannot

recycle and viruses can also

crystallize when they are outside the

host cell. So, these two characteristics

cause viruses to not meet the requirements

to be called living things. But viruses

also have the characteristics of living things, namely

having genetic material in the form of DNA or

RNA and can duplicate themselves or

replicate when they are in the

host cell. That's why viruses are called

obligate intracellular parasites or

parasites that must live in

their host cells.

The structure of viruses is very diverse. There are varieties

that are shaped like round polygonal rods

or complex ones, but

among all these forms, the

similarity is that all viruses

are covered by a protein sheath that

we usually call a capsid. Well, here

are the details of the structure of a bacteriophage. A

bacteriophage is a phage or virus

that attacks bacteria. A

bacteriophage has a head. Its head

contains DNA or RNA material. How is

its head wrapped in a

protein sheath? The capsid, yes, the capsule is composed

of protein. Then there is a tail and at the

bottom there are tail fibers that function

to attach itself to the host cell

when it will infect the host cell.

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The process of virus duplication or replication

occurs in two types of cycles or cycles. The

first is the lytic cycle.

Pay attention to the stages. First,

Selina will be visited and attached by

the virus, so the virus will attach

itself to the host cell membrane, which is

called the adsorption stage. Then the

virus will release lysozyme which

destroys the inap cell membrane and

inserts its genetic material, which is

called the penetration or injection stage.

Then the genetic material of the virus

will take over the metabolic process of the

host cell, which is called the

eclipse stage. Then the virus will utilize

the materials owned by the host cell

to synthesize or

form new viruses until finally the

cell is full of new viruses and

lysis or rupture then the new virus

will return to attack

other healthy host cells Well, those were the

stages in the viral lytic cycle,

now what about the stages in the

lysogenic cycle in the lysogenic cycle after

adoption and penetration, there will be a

fusion of host cell DNA and viruses

so that a prophage is formed, namely a

combination of host cell DNA and viruses after

the formation of the prophage, the cells will

continue to divide until one day

at the right time when the host cell

is weakening the virus will take over

the metabolism of the host cell and

synthesis eclipse occurs until finally Celine

anglicized or ruptured

hi hi hi

So if we summarize the difference

between the lytic cycle and the lysogenic cycle

is as follows in the lytic cycle

the stages are the first or option

where the virus attaches to the host cell

followed by penetration where the

virus inserts its genetic material

into the host cell then eclipse where the

virus takes over the metabolism of the

host cell followed by synthesis or

assembly of new viruses and

finally the host cell will lyse or rupture

while In the lysogenic cycle

begins with adsorption then continues

with penetration after that there is a

fusion of host cell DNA and viruses

that form prophage then continued

with host cell division when the

host cell divides then the prophage also

doubles the host cell division

will occur continuously until one

day the host cell weakens then there will be a

separation of the viral DNA and the host cell DNA

then eclipse occurs how

the virus takes over the metabolism of the

host cell then the synthesis or assembly of

new viruses until finally

Felina will break Well that was the

difference between the lytic cycle and the lysogenic cycle

Hi

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based on the genetic material it

has viruses are grouped into

two namely viruses that have

DNA genetic material and groups of viruses that

have Erna genetic material some

examples of DNA viruses are adenoviruses that

cause respiratory disorders

or tumors papovaviruses that cause

papillomaviruses warts and tumors herpes

viruses that cause herpes or chicken pox and

there are poxviruses that cause smallpox and

smallpox in cows then examples of

RNA viruses are reoviruses that cause diarrhea

picornaviruses that cause polio fever

hepatitis and digestive disorders Corona

viruses that cause respiratory disorders

flaviviruses that cause

dengue fever and Hepatitis C togaviruses that

cause rubella and encephalitis

filoviruses that cause bola

orthomyxoviruses that cause influenza

paramyxovirus causes measles and

mumps Trump virus causes rabies

and retrovirus causes it's and

leukemia

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hi hi hi

well among all the Serena virus groups

there is what we call

retrovirus this retrovirus

has a special feature Because after the

repro virus infects the cell the virus

will do reverse transcription or

commonly called Rivers transcription

retrovirus will form DNA from er

nanya by using the reverse transcriptase enzyme

is called reverse transcription because in

all living things Erna is formed from

DNA except in retroviruses forming

DNA from Erna an example of a retrovirus is

HIV which causes AIDS

Hi well next we will discuss the

disease that is currently a

pandemic throughout the world namely covert

naintin competent caused by

coronavirus precisely as big as coronavirus

two which was first discovered in China

SARS coronavirus two comes from

karlskrona Pires which mutated

this coronavirus is a group of

RNA viruses that are very easy to mutate

when the corona virus infects the

host cell then er good thing is it will do

replication or duplication well in the

replication process the virus will

adapt to the conditions of the

host cell so that changes

or mutations can occur erema well mutations that

occur in the virus arena will

causing changes in the nature of the

viruses which will certainly

result in diseases with

different symptoms and of course the treatment

will also be different until now there are

more than 10 variants of the coronavirus

coffeenine band including the exhaust

which was first discovered in England

in September 2002 the

beta variant which was first discovered in

South Africa in May

2024 the religion which was first discovered

in Brazil in November 2020 Orient

Delta which was first discovered in India

in October 2020 and then the cases

surged tremendously in Indonesia in

mid-2021 the epsilon variant

which was first discovered in the USA

in March 2020 the

zetta variant which was discovered in Brazil

In April 2017 in

various places it was discovered in

December 2020 orient earlier Philippines

January 2021 the lo variant earlier use November

2020 the ship variant in India October 2020

and the lambda variant which was first discovered

in Peru in August 2020 the

number of chronoforce variants

shows that the virus is very likely to

mutate That's why we must

remain vigilant in maintaining health protocols

for break the chain of spread of

Kobe Atlantis

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so then What is the role of viruses in

human life of course Viruses

have a beneficial role

for humans there are several

beneficial roles of viruses first for

making vaccines vaccines are made from

weakened viruses then

inserted into the human body

the aim is to activate

our immune system against

the virus then the second weakens

pathogenic bacteria will be weakened

if infected by the virus then the

third for gene therapy the gene therapy process is

usually carried out to improve the

human immune system where

we usually use retroviruses

as vectors to insert

adenosine deaminase enzymes into

abnormal lymphocytes fourth for

making interferon viruses can michu the

formation of interferon which is a protein

which is a non-specific immune response

to fight bacteria viruses or cancer

then we can also use viruses

as bioinsecticides

namely baculovirus usually baculovirus

is used as an environmentally friendly insect exterminator

besides the beneficial role of

course there is a detrimental role because viruses

are parasites so in

human life viruses can be detrimental because they

cause disease in plants animals

and humans themselves examples of viruses

that attack plants are tmv or

tobacco mosaic virus that attacks

tobacco and tomatoes then there is CV di

or citrus Vein Phloem Degeneration

that attacks citrus plants Then there is

potato yellowdoor fires disease, a

disease that attacks potato plants

and tungro virus that causes

stunting in rice plants exe file

Rp

Hi viruses also cause several

diseases in animals, for example RSV

which causes tumors in chickens bovine

papillomavirus which causes tumors

in cows Newcastle disease which

causes Newcastle disease in poultry,

especially chickens then there is Gustav virus

which causes rabies in dogs

cats and monkeys there is H5 N1 virus which is

bird flu that attacks poultry or

commonly called Avian influenza in

the end this disease became an

epidemic because it can attack humans

because it mutated Then there is also foot

and mouth disease in

livestock viruses can also cause

several diseases in humans such as

influenza caused by

orthomyxovirus smallpox caused

by herpes virus polio caused

by polio virus hepatitis

caused by hepatovirus

dengue fever caused by

dengue virus bird flu caused by

H5 N1 virus sears caused by

pora fairish Rp S which is caused by

Simplex virus AIDS caused by

HIV and ebola caused by

filovirus and many other diseases

caused by viruses

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hi okay okay

Hi Ho

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