THIRD WEEK

GOOD EVENING EVERYONE!

This week lecture is about CELL. So, i am quite not interested because i already have some knowledge on it. But, there are topics that caught my attention which are virus, prions and viroids. Well, i never heard about prions and viroids before. So, i got an expectation that prions and viroid may also cause a severe diseases just like virus does. 

VIRUS

Virus can infect animals, plants, human and even bacteria. They can only attack specific cells because they only recognize certain receptor on the cells. The common example of virus that we are familiar with are HIV and H1N1.

Dr had explain how virus reproduce, they reproduce in two ways:

LYTIC CYCLE:

                                       

                                              

LYSOGENY CYCLE:

1) Same beginning and end as lytic cycle which insert DNA, make copies and cell lyses.

2) After the DNA is inserted, it is integrated into host cell's DNA.

    Prophase: 1 gene codes for a protein that prevents

    transcription of the rest of its genes. 

3) Cell grown and replicates by binary fission normally with viral DNA

    still hiding in host DNA. 

Do you ever wonder what is a virus outside the host cell?

IT JUST A DUST!

PRIONS

Prions are proteins that transform other cellular protein (PrPC) to the prion form PrP^SC. Prions are normal proteins that become folded incorrectly due to mutation. Prions cause fatal, neurological degenerative diseases, including Creutzfeldt-Jakob disease (CJD), kuru, scrapie (Transmissible spongiform encephalopathy), mad cow disease (Bovine spongiform encephalopathy) and chronic wasting disease.

  

What makes prions so special?

    ·      Prions are resistant to inactivation by heating to 90°C, which will
           inactivate viruses.

   ·       Prion infection is not sensitive to radiation treatment that 
           damages virus genomes.

   ·       Prions are not destroyed by enzymes that digest DNA or RNA.

   ·       Prions are sensitive to protein denaturing agents such as 
           phenol and urea.

   ·       Prions have direct pairing of amino acids.

VIROIDS

Viroids are infectious RNA. These are Circular RNA molecules which infect plants. Viroids are the smallest infectious pathogens known. This RNA molecule Don’t code for proteins and disrupt regulatory systems in plants. It Causes growth problems in plants. Well guys that was that! They are bad guys! We need to choose a clean and healthy food to avoid them because once we are infected, no cure for it! Thank you!