Disease: Viruses | A-level Biology | OCR, AQA, Edexcel

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The key points covered of this video include:

1. Introduction to Viruses
2. Structure of Viruses
3. Structure of HIV

Introduction to Viruses

A virus is a type of pathogen. Viruses are non living and are particles which means they are just a collection of molecules. Viruses can only replicate inside living host cells.Viruses have to enter the cells of the host they infect in order to survive. They hijack the host cell protein production machinery to replicate. After reproducing in the host the new virus particles burst out of the host cell and kill it. This process is how viruses infect the host and cause disease.

Structure of Viruses

Viruses are very different to bacteria. Viruses do not have any organelles because they are not cells. They cannot make their own proteins because they do not have ribosomes. Viruses have genetic material which can be either DNA or RNA. The virus genetic material is enclosed inside a protein coat called a capsid. On the viral membrane surface viruses have attachment proteins which allow the virus to attach to host cells. These attachment proteins are viral antigens. We can summarize the differences between bacteria and viruses.

Structure of HIV

The human immunodeficiency virus (HIV) is a virus that infects humans and causes acquired immune deficiency syndrome (AIDs). HIV has a lipid envelope. HIV has RNA as its genetic material. HIV has an enzyme called reverse transcriptase which generates DNA from the HIV RNA. HIV is called a retrovirus because it generates DNA from RNA using reverse transcriptase. This DNA generated will then integrate into the host cell DNA. This will result in the generation of new HIV particles using host cell machinery.

Summary

Viruses are non-living particles
Viruses can only replucate inside living host cells
Viruses have no organelles
Viruses have genetic material which is either DNA or RNA
The viral genetic material is enclosed in a protein coat called a capsid Viruses have attachment proteins which allow them to attach to host cells
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(Don't mind me just putting some timestamps for personal use) start at 6:34

dilukshfernando
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Do you have a vide talking about the other viruses named on the OCR spec? We've been told we have to know about Tobacco Mosaic virus and influenza as well...

catrionadowner
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Thanks a lot, I am preparing for medical school and these help.

tatianaasi
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How do you change the original cusor to the pen-shaped cursor on ipad? Thank you <3

haluongthuy
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Enjoyed your videos. Helped out a lot.
Got a Question though, , My booklet mentions budding a lot but you guys didn't mention it.
Is it important?

ahadmalik
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The capsid u referred too is the envelope.

itsjustyana
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So a bacteria enters into a cell because the proteins in it attach to the receptors on the host cell and the host cell is tricked into thinking that it’s a useful molecule so the bacteria enters ???

hitwickeywicket
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