Solution:
Myoglobin has a single chain of 153 amino acids wrapped around a group of iron and other atoms (called "heme") to which oxygen binds. Hemoglobin, in contrast, is made of up four chains: two identical chains consisting of 141 amino acids, and two other identical chains consisting of 146 amino acids.
Because amino acids can be arranged in many different combinations, it's possible for our body to make thousands of different kinds of proteins from just the same 21amino acids. There are only 20 amino acids.
The 20 Amino acids which make proteins are:
• alanine - ala - A (gif, interactive)
• arginine - arg - R (gif, interactive)
• asparagine - asn - N (gif, interactive)
• aspartic acid - asp - D (gif, interactive)
• cysteine - cys - C (gif, interactive)
• glutamine - gln - Q (gif, interactive)
• glutamic acid - glu - E (gif, interactive)
• glycine - gly
