... 9 different neuraminidase serotypes (different types of the proteins) discovered (mvm, 10/10/02). However there has only been three HA subtypes (H1 - 3) and two NA subtypes (N1, N2) discovered in humans (mvm, 10/10/02). Antigenic shift only ever occurs in the influenza A virus. This occurs when there is a rapid ... of no threat. The subtype of the influenza virus is also determined using the antigenicity of neuraminidase (NA). A spike of NA contains 4 NA monomers, hence is called a tetramer (angelfire, 9/10/02). The head of each NA molecule is topped with a box like structure. The catalyt...

• Word Count: 1687
• Approx Pages: 7
• Grade Level: High School

... be called an isotope of carbon. The number of electrons in an atom can also vary when the atom is involved in a chemical reaction. For example, if a neutral sodium atom (Na is the chemical symbol for sodium) loses and electron to a neutral chlorine atom (Cl) during a chemical reaction, the result would be called a sodium ion (written as ... Na+) and a chloride ion (written as Cl-). Chemical Bonding Chemical bonds form between atoms when it is energetically favorable. A chemical bond forms when two atoms share two electrons between them. A double ... ...

• Word Count: 10700
• Approx Pages: 43
• Grade Level: High School

... atoms want to bond in order to become stable. That means it wants to get rid of it to become stable. The loss of the one electron makes a sodium ion (Na+), which is positively charged. It's positively charged because it lost one of it's negatively charged electrons. Thus, the electrons and protons don't balance, because now there is one more proton ... ...

• Word Count: 4152
• Approx Pages: 17
• Grade Level: High School