Questions

Rafael Nadal defeated Daniil Medvedev in the men's singles title at the 2019 US Open. It was Nadal's 19th Grand Slam singles title, and fourth US Open title.

Amino acids are organic compounds containing amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid.

Depending on the nature of the side chain groups, three classes of aminoacids can e distinguished:

1. Amino acids with H ond donor and acceptor groups.

Histidine, lysine, aspartic acid, threonine,...

2. Amino acids with donor grups only.

Arginine, tryptophan and cysteine.

3. Amino acids with acceptor groups only.

Asparagine and glutamine.

The act of formally approving something is known as Ratification.

Protons carry a positive electrical charge, electrons carry a negative electrical charge and neutrons carry no electrical charge at all. The protons and neutrons cluster together in the central part of the atom, called the nucleus, and the electrons 'orbit' the nucleus.