Nucleosides and Nucleotides

• Nucleic acids are unbranched polymers composed of repeating monomers called nucleotides.
• •There are two types of nucleic acids: DNA and RNA.
• •DNA (deoxyribonucleic acid) stores the genetic information of an organism and transmits that information from one generation to another.
• •RNA (ribonucleic acid) translates the genetic information contained in DNA into proteins needed for all cellular function.
• Nucleoside VS. Nucleotides:

  NUCLEOSIDES contains only sugar and a base whereas NUCLEOTIDES contain sugar, base, and a phosphate group.
• •The nucleotide monomers that compose DNA and RNA consist of: a monosaccharide, a N-containing base, and a phosphate group:
• •DNA molecules contain several million nucleotides, while RNA molecules have only a few thousand.

  •DNA is contained in the chromosomes of the nucleus, each chromosome having a different type of DNA.
• •Humans have 46 chromosomes (23 pairs), each made up of many genes.
• •A gene is the portion of the DNA molecule responsible for the synthesis of a single protein.
• How many portion of DNA is translated?

  2%
• •In RNA the monosaccharide is the aldopentose D-ribose.

  
• •In DNA, the monosaccharide is the aldopentose D-2-deoxyribose.

  
• N-containing bases: Adenine, Uracil, Cytosine, Guanine, Thymine.
• Pyrimidine is the parent compound of Cytosine (Cytidine), Uracil (Uridine), Thymine (Thymidine). *if found in DNA add prefix deoxy*
• Purines are the parent compounds of Adenine (Adenosine), Guanine (Guanosine)
• DNA contains bases A, G, C, and T.
• RNA contains bases A, G, C, and U.
• Name the compound:

  A) cytosine (C)

  B) uracil (U)

  C) thymine (T)

  
• Name the compound:

  A) adenine (a)

  B) guanine (G)

  
• •A nucleoside is formed by joining the anomeric carbon of the monosaccharide with a N atom of the base by a glycosidic bond
• •To name a nucleoside derived from a pyrimidine base, use the suffix “-idine”.

  •To name a nucleoside derived from a purine base, use the suffix “-osine”.
• •Nucleotides are formed by adding a phosphate group to the 5′-OH of a nucleoside.
• •Nucleic acids (DNA and RNA) are polymers of nucleotides joined by phosphodiester linkages.

  
• •A polynucleotide contains a backbone consisting of alternating sugar and phosphate groups.
• •The identity and order of the bases distinguish one polynucleotide from another (primary structure).

  •In DNA, the sequence of the bases carries the genetic information of the organism.
• •A polynucleotide has one free phosphate group at the 5’ end and one free OH group at the 3’ end.
• •The DNA model was initially proposed by Watson and Crick in 1953.
• •DNA consists of two polynucleotide strands that wind into a right-handed double helix.
• •The two strands run in opposite directions; one runs from the 5’ end to the 3’ end and the other runs from the 3’ end to the 5’ end.
• •The sugar-phosphate groups lie on the outside of the helix and the bases lie on the inside.
• •The bases always line up so that a pyrimidine derivative can hydrogen bond to a purine derivative on the other strand.
• COMPLEMENTARY BASE PAIRS:

  •Adenine pairs with thymine with 2 hydrogen bonds to form an A—T base pair.

  •Cytosine pairs with guanine using 3 hydrogen bonds to form a C—G base pair.
• •The information stored in DNA is used to direct the synthesis of proteins.
• PROCESS:

  1. Replication is the process by which DNA makes a copy of itself when a cell divides.
• PROCESS:

  2. Transcription is the ordered synthesis of RNA from DNA; the genetic information stored in DNA is passed onto RNA.
• PROCESS:

  •Translation is the synthesis of proteins from RNA; the genetic information determined the specific amino acid sequence of the protein.
• •The original DNA molecule forms two new DNA molecules, each of which contains a strand from the parent DNA and one new (TEMPLATE) strand.
• LAGGING strand replicates in segments
• LEADING strands replicates as a whole.
• Replication proceeds in the 3'-5' direction of the template DNA.