Destroyer Bio # 409

[jLaws]

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It says this statement is true: A polypeptide with 5 different amino acids can have 120 possible sequences.

If there are 20 different amino acids and you have a polypeptide with 5 different amino acids then wouldn't the answer be many more than 120 possible sequences? 20x19x18x17x16=1860480. Or is this problem assuming a fictional world where only 5 amino acids exist...

 

[artist2022]

EDIT: I overthought this too, lol. Nmcoy has the right explanation!

 

[jLaws]

Thank you for responding but I disagree. The amount of possible sequences will always be the number that I arrived at assuming 20 amino acids. The amount of possible sequences should never change.

 

[Nmcoy]

Thank you for responding but I disagree. The amount of possible sequences will always be the number that I arrived at assuming 20 amino acids. The amount of possible sequences should never change.

Don’t think too much into it. If it said “There is a chain w/ 20 Amino Acids, how many possible sequences are there?” then I think your method of thinking would be correct. But it’s only saying there are 5 Amino Acids in the chain. So it’s just 5! Or 5x4x3x2x1= 120. I hope that helps!

 

[jLaws]

here's another. question 479 says this is true: surfactant reduces surface tension and allows the fetus to breath easier.
Fetuses don't breathe with their lungs though, they get O2 from the placenta, correct?

 

[jLaws]

Don’t think too much into it. If it said “There is a chain w/ 20 Amino Acids, how many possible sequences are there?” then I think your method of thinking would be correct. But it’s only saying there are 5 Amino Acids in the chain. So it’s just 5! Or 5x4x3x2x1= 120. I hope that helps!

If the chain had 20 amino acids my calculation would not be correct

 

[jLaws]

and another: #491 says this is false: the wing of a bird may be considered a vestigial structure.
Kiwi are a bird with vestigial wings...

 

[Nmcoy]

If the chain had 20 amino acids my calculation would not be correct

This is true, my apologies. I never took the time to actually multiply it out. If it were a chain of 20, I believe the answer would be 2.4329 x 10^18.

 

[LittleKay]

here's another. question 479 says this is true: surfactant reduces surface tension and allows the fetus to breath easier.
Fetuses don't breathe with their lungs though, they get O2 from the placenta, correct?

When they are being birthed they need to breathe. The surfactant is necessary to reduce surface tension so they can force the lungs to inflate and begin breathing on their own.