20Jan_6 - Biological Science I Tuesdays and Thursdays...

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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 20 January 2010 – Lecture 6 NUCLEIC ACIDS - Store and transmit hereditary information The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene Genes are made of DNA, a nucleic acid There are two types of nucleic acids: - Deoxyribonucleic acid (DNA) - Ribonucleic acid (RNA) DNA provides directions for its own replication DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis Protein synthesis occurs in ribosomes 1. Nucleic Acid Structure a. Nucleic acids are polymers called polynucleotides b. Each polynucleotide is made of monomers called nucleotides c. Each nucleotide consists of: c.i. a nitrogenous base c.ii. a pentose sugar c.iii. and a phosphate group d. The portion of a nucleotide without the phosphate group is called a nucleoside 2. Nucleotide Monomers a. Nucleoside = nitrogenous base + sugar b. There are two families of nitrogenous bases: b.i. Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring b.ii. Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring c. The sugars between DNA and RNA differ: c.i. DNA, the sugar is deoxyribose c.ii. RNA, the sugar is ribose d. Nucleotide = nucleoside + phosphate group 3. Nucleotide Polymers a. Nucleotide polymers are linked together to build a polynucleotide b. Adjacent nucleotides are joined by covalent bonds that form between the –OH group on the 3’ carbon of one nucleotide and the phosphate on the 5’ carbon on the next c. These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages d. The sequence of bases along a DNA or mRNA polymer is unique for each gene 4. The DNA Double Helix 1
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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 20 January 2010 – Lecture 6 a. A DNA molecule has two polynucleotides spiraling around an imaginary axis, forming a double helix b. In the DNA double helix, the two backbones run in opposite 5’ 3’ directions from each other, an arrangement referred to as antiparallel c. The nitrogenous bases in DNA pair up and form hydrogen bonds: c.i. adenine (A) always with thymine (T) (two hydrogen bonds) c.ii. guanine (G) always with cytosine (C) (three hydrogen bonds) YOU SHOULD NOW BE ABLE TO: List and describe the four major classes of molecules Describe the formation of a glycosidic linkage and distinguish between monosaccharides, disaccharides, and polysaccharides Distinguish between saturated and unsaturated fats and between cis and trans fat molecules Describe the four levels of protein structure Distinguish between the following pairs: pyrimidine and purine, nucleotide and nucleoside, ribose and deoxyribose, the 5’ end and 3’ end of a nucleotide 2
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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 20 January 2010 – Lecture 6 1. CELLS – The Fundamental Unit of Life A.
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