Nucleic Acids

Your Assignment

Your Nucleic Acid Assignment 1. Define, compare and give examples of the two types of nucleic acids (structure, location and function). 2. What are the main uses of nucleic acids in cells (plants and animals)??

Additional Resources (1) The Tree of Life, Proteins and nucleic acids module

Additional Resources (2) Nucleic Acids Web links DNA Timeline: http://www.dnai.org/timeline/ Nobel Organisation DNA information site: http://www.nobelprize.org/educational/medicine/dna_double_helix/readmore.html

Nucleic acids Ribo-nucleic acid (RNA) Deoxyribonucleic Acid (DNA) They are polymers made up of repeating monomer units called nucleotides DNA is double stranded helix, RNA is single C-H-O-N-P atoms 21

Nucleic acids store and transmit hereditary information Information flows from DNA  RNA  Proteins

Nucleotides: the monomers of nucleic acids Consist of 3 parts: 5 Carbon Sugar (Pentose) Ribose or Deoxyribose Phosphate group Nitrogenous Base Purines (A and G) (6 membered ring of C and N fused to a 5 membered ring) Pyrimidines (C, T, and U) (6 membered ring) Only certain bases are compatible for bonding together, Adenine with Thymine (A-T) and Cytosine, Uracil with Guanine (C-G) Sequence of bases is unique to each gene

Nucleotide Structure 3 components: Pentose sugar Organic base Phosphate sugar base Stay the same Changes Contains nitrogen & carbon Pentose sugar (5 Carbon atoms) 3 components: Pentose sugar (ribose in DNA) Phosphoric acid Organic base (always contains nitrogen)

5 nitrogenous bases

4 Bases Purines – Pyrimidines – Double ringed structure Single ringed structure

Nucleic acids are polymers of nucleotides (polynucleotides) joined by phosphodiester bonds (phosphate to sugar)

Bondings The base and sugar join with a: glycosidic bond The phosphate and sugar join with an: ester bond Both require a condensation reaction to occur 

2 condensation reactions occur in the formation of a nucleotide: Phosphate 2 condensation reactions occur in the formation of a nucleotide: H Ester bond OH Glycosidic bond OH H Base Sugar

DNA Genetic material inherited from parents Extremely long: hundreds-thousands of genes Contains the information that programs cellular activities DNA is “read” by proteins and translated into proteins. Double stranded helix Has the ability to copy itself

Complementary Base Pairing *Purines always pair with pyrimidines* A joins to T (2 hydrogen bonds) C joins to G (3 hydrogen bonds) see

5’ 3 hydrogen bonds 3’ C G 0.34nm A T 3’ 2 hydrogen bonds 5’ 2nm

Bonding relationships Type of Base Purine Pyrimidine Structure Bonding relationships Adenine Guanine Thymine Cytosine = hydrogen bond

Type Purine Pyrimidine Structure Name Adenine Guanine Thymine Cytosine / Uracil

RNA Messenger RNA (mRNA) conveys the DNA code out of the nucleus to the cytoplasm (ribosome) Single stranded Multiple complex structures A,U,G,C

RNA can adopt complex 3-D structures and is not restricted to the double helix structure RNA carries information from DNA (nucleus) to the ribosome via reverse transcription, followed by translation.

Nucleotide 3 components: Pentose sugar; deoxyribose Phosphate group Nitrogenous base; 4 types: Join by condensation phosphate base Stay the same sugar Changes Contains nitrogen & carbon Ribose sugar in RNA Deoxyribose sugar in DNA Pentose sugar (5 Carbon atoms)

Molecular Clocks Linear sequences of nucleotides in DNA are passed from parent to offspring. DNA determines the amino acid sequence of proteins Siblings have DNA that is more alike than an unrelated person 2 species should have similar DNA if they are closely related based on fossil and anatomical evidence The more differences in the DNA codes, the longer the time the two species have evolved separately.