In order to understand 1) protein synthesis, or the production of proteins, it is important to understand RNA and how it is transcribed from DNA. And in order to understand 2) transcription, or the process by which genetic information is copied from DNA to RNA, it is important to understand both the structure and replication of DNA, which is the source of the genetic information that tells cells which proteins to make and when to make them. A DNA molecule is made up of two long chains of nucleotides, which are the basic structural units of nucleic acids. One nucleotide consists of three parts: a sugar molecule, called 3) deoxyribose, a phosphate group, and a 4) nitrogen-containing base. The two nucleotides are covalently bonded together between the deoxyribose and phosphate molecules. A key concept to also understand is that there are four kinds of nitrogen-containing bases. This is important because they bond with each other by means of hydrogen bonds in a way that forms the 5) double helix shape of DNA and the way they pair led to suggestions of how DNA copies itself. The four kinds of nitrogen-containing bases are 6) adenine, 7) guanine, 8) cytosine, and 9) thymine. 10) Base-pairing rules are two rules that describe how these bases: they state that cytosine bonds with guanine and adenine bonds with thymine. These two pairs of bases are known as 11) complementary base pairs.
Because protein synthesis requires RNA, and RNA comes from DNA, there must be enough DNA to produce RNA. The process in which DNA is copied is called 12) replication. Replication occurs when the two nucleotide chains of DNA separate by unwinding, and each chain serves as a template for a new chain. During replication, enzymes called 13) helicases separate DNA’s two chains of nucleotides at the 14) replication fork. Other enzymes, called 15) DNA polymerases, bind to the separated chains, and one at a time construct a new complementary chain of nucleotides based on the sequence of the...
Please join StudyMode to read the full document