GCSE Biology - What Is a Virus? - Examples of Viral Disease (HIV, Measles & TMV) #36

Summary

This video delves into the nature of viruses, which are non-cellular organisms that can only replicate by hijacking host cells. It explores three viral diseases: measles, a highly contagious disease with a characteristic rash and fever, now rare in the UK due to widespread vaccination; HIV, which weakens the immune system and can progress to AIDS, but is manageable with antiretroviral drugs; and the tobacco mosaic virus, which affects plants like tobacco, causing a mosaic pattern on leaves and hindering photosynthesis.

Takeaways

• 🦠 Viruses are not cells and are not considered living organisms, yet they are classified as organisms.
• 🔍 Viruses are approximately 10,000 times smaller than animal cells and cannot reproduce on their own.
• 🌀 Once inside a host cell, viruses can hijack the cell's machinery to replicate and produce many copies of themselves.
• 💥 The process of viral replication and cell bursting can lead to damage in our bodies, causing illness.
• 📣 Measles is a viral disease spread through droplets from coughs or sneezes, causing a rash and fever.
• 💉 Measles is rare in the UK due to widespread vaccination, but it can be serious and sometimes fatal.
• 🚫 HIV is transmitted through sexual contact and sharing of bodily fluids like blood, and it attacks the immune system.
• 🤒 Initial HIV infection might present flu-like symptoms, but it can progress to severely weaken the immune system, leading to AIDS.
• 💊 Antiretroviral drugs can prevent HIV replication, allowing those with access to treatment to live normal lives.
• 🌿 The tobacco mosaic virus (TMV) affects plants, causing a mosaic pattern on leaves and disrupting photosynthesis.

Q & A

What is a virus and how does it differ from living cells?

A virus is not a cell and is not considered living. It is an organism that is about 10,000 times smaller than animal cells and cannot reproduce by itself. It requires the machinery of a host cell to replicate.

How do viruses cause illness in the body?

Viruses cause illness by colonizing and then bursting host cells, which damages the body's tissues and can lead to various symptoms depending on the type of virus.

What are the three viral diseases discussed in the video?

The three viral diseases discussed in the video are measles, HIV, and tobacco mosaic virus.

How is the measles virus typically transmitted?

The measles virus is transmitted through droplets when an infected person coughs or sneezes.

What are the common symptoms of measles?

Common symptoms of measles include a red rash across most of the body and a fever, which is characterized by a high temperature and general malaise.

Why is measles rare in the UK?

Measles is rare in the UK because nearly everyone is vaccinated against it.

How can HIV be transmitted and what does it stand for?

HIV can be transmitted through sexual contact, sharing needles, or exchanging bodily fluids like blood. HIV stands for human immunodeficiency virus, indicating it affects humans and causes an inadequate immune system.

What is the difference between HIV and AIDS?

HIV is the virus itself, while AIDS (Acquired Immunodeficiency Syndrome) is the advanced stage of the HIV infection where the immune system is severely compromised and the person is susceptible to unusual infections and cancers.

What are antiretroviral drugs and how do they help in treating HIV?

Antiretroviral drugs are medications that prevent the HIV virus from replicating within the body. If taken early in the disease, they can help people with HIV live normal lives.

What is the tobacco mosaic virus and how does it affect plants?

The tobacco mosaic virus (TMV) is a virus that affects certain plant species like tobacco and tomato plants. It causes discolored patches on leaves, disrupting photosynthesis and thus hindering the plant's ability to produce enough sugars for proper growth.

What is the significance of the term 'mosaic' in the context of the tobacco mosaic virus?

The term 'mosaic' refers to the discolored patches that the virus causes on the leaves, forming a mosaic pattern, which disrupts the plant's photosynthesis and growth.

Outlines

00:00

🦠 Understanding Viruses and Their Impact

This paragraph introduces viruses, explaining that they are not cells and not living organisms but are still considered organisms. Viruses are very small, about 10,000 times smaller than animal cells, and cannot reproduce on their own. However, once inside a host cell, they can use the cell's machinery to replicate. This replication and subsequent bursting of cells can damage the body and cause illness. The paragraph also sets the stage for discussing three specific viral diseases: measles, HIV, and the tobacco mosaic virus.

Keywords

💡Virus

A virus is a microscopic infectious agent that can only replicate inside the living cells of an organism. In the context of the video, viruses are described as non-cellular entities that are not considered 'alive' in the traditional sense because they cannot reproduce on their own. They are, however, capable of infecting host cells and using the host's cellular machinery to replicate. The video explains that viruses are about 10,000 times smaller than animal cells and cause diseases by colonizing and then bursting cells, leading to illness.

💡Measles

Measles is a highly contagious viral disease that typically causes a red rash across the body and fever. The video mentions that measles is spread by droplets when an infected person coughs or sneezes. It also notes that measles can be serious and sometimes fatal, but it is rare in the UK due to widespread vaccination.

💡HIV

HIV stands for Human Immunodeficiency Virus, which is a virus that attacks the immune system, specifically the CD4 cells, also known as T cells. The video explains that HIV leads to a deficient immune system, making individuals more susceptible to infections and diseases. It is important to distinguish between HIV, the virus, and AIDS, the advanced stage of the disease. The video also discusses the use of antiretroviral drugs to manage the virus and prevent the progression to AIDS.

💡AIDS

AIDS, or Acquired Immunodeficiency Syndrome, is the final stage of HIV infection, where the immune system is severely damaged, and the body cannot fight off infections and diseases. The video describes AIDS as a disease where the immune system can no longer cope, leading to unusual infections and sometimes cancers. It highlights the historical context where AIDS was often fatal, but with the advent of antiretroviral drugs, people living with HIV can now manage the virus and live normal lives.

💡Tobacco Mosaic Virus (TMV)

Tobacco Mosaic Virus is a plant virus that affects certain species like tobacco and tomato plants. The term 'mosaic' refers to the discolored patches it creates on leaves, disrupting photosynthesis and thus the plant's ability to produce sugars for growth. The video uses TMV as an example to show that viruses can also infect plants, causing damage to their growth and development.

💡Droplets

Droplets are small liquid particles that can carry pathogens, such as viruses, from one person to another. In the context of the video, droplets are mentioned as a mode of transmission for the measles virus, which can spread when an infected person coughs or sneezes, releasing these droplets into the air.

💡Replication

Replication in the context of viruses refers to the process by which they make copies of themselves. The video explains that viruses cannot replicate on their own; they must infect a host cell and hijack its machinery to produce more virus particles. This process is central to how viruses spread and cause disease.

💡Colonizing

In the context of the video, colonizing refers to the process by which viruses invade and take over host cells. Once inside the cell, the virus uses the cell's machinery to replicate, creating more virus particles. This colonization can lead to the destruction of the host cell, which is a key mechanism by which viruses cause harm.

💡Bursting

Bursting, as described in the video, is the process where a virus-infected cell ruptures, releasing new virus particles. This is a critical step in the viral life cycle, as it allows the newly formed viruses to spread and infect other cells, continuing the cycle of infection.

💡Vaccination

Vaccination is the process of administering a vaccine to stimulate immunity to a particular disease. The video mentions that measles is rare in the UK due to widespread vaccination, highlighting the importance of vaccines in preventing viral diseases and reducing their spread.

💡Antiretroviral drugs

Antiretroviral drugs are medications used to treat and prevent HIV infection by inhibiting the virus's replication. The video explains that these drugs can prevent the progression of HIV to AIDS, allowing people living with HIV to maintain a relatively normal life if they have access to early treatment.

Highlights

Viruses are not cells and not living, yet considered organisms.

Viruses are about 10,000 times smaller than animal cells.

Viruses cannot reproduce by themselves but can use host cell machinery to replicate.

Viral replication can damage host cells leading to illness.

Measles virus spreads through droplets from coughs or sneezes.

Measles causes a red rash and fever.

Measles is rare in the UK due to widespread vaccination.

HIV can be transmitted through sexual contact and sharing needles.

HIV stands for human immunodeficiency virus, affecting the immune system.

Initial HIV infection may present flu-like symptoms.

HIV progressively weakens the immune system, leading to AIDS if untreated.

AIDS is a syndrome where the immune system cannot cope with infections and cancers.

Antiretroviral drugs can prevent HIV replication, allowing for normal life expectancy.

Tobacco mosaic virus (TMV) affects certain plant species, causing discolored patches.

TMV disrupts photosynthesis, hindering plant growth and sugar production.

The video concludes with an invitation for viewers to like and return for more content.

Transcripts

in this video we're gonna take a look at

what viruses are and at three of the

disease is the leading cause now viruses

are quite hard to explain

they aren't cells and they're not living

but we only still consider them to be

organisms there are about 10,000 times

smaller than animal cells and they can't

reproduce by themselves however what

they get inside another organism cell

they can use that cells own machinery to

make loads of copies of themselves

and then when the time is right it can

burst the cell and all of those new

viruses will have to find new cells to

take over

this process of colonizing and then

bursting our cells is obviously going to

damage our bodies and that's one of the

main reasons that viruses make us feel

ill

the three examples of viral disease that

we're going to look at are measles HIV

and tobacco mosaic virus

the measles virus is spread by droplets

when an infected person coughs or

sneezes it generally causes people to

develop a red rash across most of their

body and the fever which is where you

get a really high temperature and

generally feel unwell although it can be

really serious and sometimes even fatal

it's luckily really rare in the UK as

nearly everyone is vaccinated against

her when a young

a GRB on the other hand can be spread by

sexual contact such as unprotected sex

all by exchanging bodily fluids such as

the blood for example when people share

needles

HIV stands for human immunodeficiency

virus which tells us that affects humans

and it causes a deficient or inadequate

immune system

and it's a bit weird but when you use

the term HIV you're referring to the

actual virus not to disease

when somebody first catches HIV it might

get flu-like symptoms for a few weeks so

fever tiredness and aches but then I'll

start to feel better and think they're

everything's fine

however inside their body the parties

are doing more and more damage to their

immune system and at some point the

immune system becomes so weak that they

start to catch unusual infections and

sometimes even get cancers

at this point we say that the person has

developed AIDS which is classed as a

disease or syndrome in which the

person's immune system can't cope

anymore

this used to be the end of the story as

people would die of random infections or

cancer now they're with a group of

medications called antiretroviral drugs

which prevent the virus from replicating

within our bodies so as long as people

have access to these medications early

on in their disease that they can go on

to live normal lives

the last viral disease we're going to

cover is caused by tobacco mosaic virus

or tmv this virus affects plants instead

but only certain species such as tobacco

and martyr plants

the reason is called mosaic is because

it dis colours patches on the leaves

causing a mosaic pattern to form the

problem is a photosynthesis can take

place and it's discolored patches and so

overall the plant won't be able to

produce enough sugars for proper growth

and that's all for now if you enjoyed it

then please do give us a like and we'll

see you next time