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how is bacteria affected by the acidity of the stomach ?

the things that i know right now are that they form enzymes which neutralises the acid but can someone further explain this because i dont understand how this would be useful for the bacteria?
also whilst doing a past paper i came across a question that said if we add a digestive protein enzyme it stops it from causing cell damage. How does that happen??? Please can someone help thank you.
Original post by megakhadkax
the things that i know right now are that they form enzymes which neutralises the acid but can someone further explain this because i dont understand how this would be useful for the bacteria?
also whilst doing a past paper i came across a question that said if we add a digestive protein enzyme it stops it from causing cell damage. How does that happen??? Please can someone help thank you.


Have you learnt about optimum living conditions for organisms - things like the optimum temperature, pH, humidity, etc.?

Enzymes also have an optimum temperature and pH, at which they are at their most efficient. This is usually around 37oC and on average, around about pH 7. If you deviate from these points too much, it can cause the enzyme to either become less active, or denature completely.

In the stomach, the pH is usually around 1-2, which is very acidic for most enzymes. This can cause enzymes to become denatured, as the acidity affects the ionisation of individual amino acids within an enzyme (enzymes are proteins, which are made up of amino acids), which affects their tertiary structure, causing the active site of the enzyme to change shape. This means that the substrate cannot bind as effectively, meaning that the reaction will not be carried out very efficiently.

Bacteria are prokaryotic organisms that have many different enzymes that are required for various functions - if you denature a lot of these, the bacteria will die, because basic functions like cellular respiration might not take place very efficiently. The same is true if the temperature deviates significantly from the optimum temperature.

Hope this helps!
Reply 2
Original post by thegodofgod
Have you learnt about optimum living conditions for organisms - things like the optimum temperature, pH, humidity, etc.?

Enzymes also have an optimum temperature and pH, at which they are at their most efficient. This is usually around 37oC and on average, around about pH 7. If you deviate from these points too much, it can cause the enzyme to either become less active, or denature completely.

In the stomach, the pH is usually around 1-2, which is very acidic for most enzymes. This can cause enzymes to become denatured, as the acidity affects the ionisation of individual amino acids within an enzyme (enzymes are proteins, which are made up of amino acids), which affects their tertiary structure, causing the active site of the enzyme to change shape. This means that the substrate cannot bind as effectively, meaning that the reaction will not be carried out very efficiently.

Bacteria are prokaryotic organisms that have many different enzymes that are required for various functions - if you denature a lot of these, the bacteria will die, because basic functions like cellular respiration might not take place very efficiently. The same is true if the temperature deviates significantly from the optimum temperature.

Hope this helps!

Does this mean that when the bacteria binds to the acid it neutralises the pH, this increases the pH making it less acidic so the bacteria can survive and replicate to cause damage to the cell.
Original post by megakhadkax
Does this mean that when the bacteria binds to the acid it neutralises the pH, this increases the pH making it less acidic so the bacteria can survive and replicate to cause damage to the cell.


I'm not too sure about the second part to the original question in the OP - would you be able to post the full question? What I explained in my previous post was to show how pH affects bacterial survivability. The acid produced by the stomach is a first-line host defence mechanism against microbes.
I think the protein digesting enzymes digest the neutralising enzymes so the acid in the stomach is not neutralised so the bacteria cant survive?

Not sure
but if im right i'd love a thumbs up! :smile:

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