What are some ways that human affect the carbon cycle?

Burning fossil fuel which releases CO2 into atmosphere and enhance global warming,Deforestation,limestone mining.

Six amino acids have side chains that are polar but not charged. these are serine (ser), threonine (thr), cysteine (cys), asparagine (asn), glutamine (gln), and tyrosine (tyr). these amino acids are usually found at the surface of proteins, as discussed in the proteins 2 module.