Unit 2 Study guide

1. The atom is the smallest part of matter that represents a particular element. For quite a while, the atom was thought to be the smallest part of matter that could exist. But in the latter part of the 19th century and early part of the 20th, scientists discovered that atoms are composed of certain subatomic particles and that, no matter what the element, the same subatomic particles make up the atom. The number of the various subatomic particles is the only thing that varies.
2. There is a difference between the meanings of atomic mass and mass number. One is the average weight of an element and the other is the total number of nucleons in the atom's nucleus.
3. Variants of a particular element. Examples are carbon-12
5. pH is not very important in anatomy itself, but in physiology it is crucial because the body has to be at a specific pH in order for organs to function properly. Certain physiological reactions will not occur if the pH level is not at the correct level.
6. 1. Proteins = monomers (building blocks) are amino acids and proteins are used for various reasons in cell such as structure, defense, modification. An example of a protein is hemoglobin that red blood cells used to carry oxygen.
2. Carbohydrates = monomers (building blocks) are monosaccarides with the general formula of CH20. Carbohydrates can be used for storage or energy or even for structure, such as the cellulose that makes up the plant cell wall.
3. Nucleic Acids = RNA and DNA, the monomers of both of them are nucleotides and nucleic acids are used to transfer their genetic information which codes for proteins. In other words, they code for production of specific proteins.
4. Lipids = Includes glycerides, phospholipids, and steroids. The main important point of lipids is that they are all virtually hydrophobic and nonpolar. Lipids are extremely good in storing energy and that is their main function. They do not really have a monomer, though fatty acids do make up a main part of glycerides.
10. 1. Primary: refers to the unique sequence of amino acids in the protein. All proteins have a special sequence of amino acids, this sequence is derived from the cell's DNA.

2. Secondary : the coiling or bending of the polypeptide into sheets is referred to the proteins secondary structure. alpha helix or a beta pleated sheet are the basic forms of this level. They can exist separately or jointly in a protein.

3. Tertiary: The folding back of a molecule upon itself and held together by disulfide bridges and hydrogen bonds. This adds to the proteins stability.

4. Quaternary: Complex structure formed by the interaction of 2 or more polypeptide chains.
11. ATP is a molecule made up of 3 phosphate molecules and one nitrogenous base. there is a high energy bond between the 3rd and 2nd phosphate, which can be broken down into ADP + P this is a reversible reaction.
12. The plasma membrane, which serves as a diffusion barrier between the cell and its environment. All living cells have plasma membranes. A "diffusion barrier" prevents the loss of cellular materials by interfering with the physical tendency of molecules to spread out. It also