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Nucleic Acids

Nucleic Acids - Nucleic Acids Nucleic DNA& RNA What are...

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Unformatted text preview: Nucleic Acids Nucleic DNA & RNA What are they ? What The 4th type of macromolecules macromolecules The chemical link between The generations generations The source of genetic The information in chromosomes information What do they do ? What Dictate amino-acid sequence amino-acid in proteins in Give information to chromosomes, which is then passed from parent to offspring What are they made of ? What Simple units called nucleotides, Simple nucleotides connected in long chains connected Nucleotides have 3 parts: have 1- 5-Carbon sugar (pentose) 2- Nitrogen containing base 2(made of C, H and N) (made 3- A phosphate group ( P ) The P groups make the links that unite The the sugars (hence a “sugar-phosphate the sugar-phosphate backbone” backbone” Two types of Nucleotides Two (depending on the sugar they contain) contain) 1- Ribonucleic acids (RNA) 1- Ribonucleic The pentose sugar is Ribose The Ribose (has a hydroxyl group in the 3rd (has carbon---OH) carbon--2- Deoxyribonucleic acids (DNA) 2- Deoxyribonucleic The pentose sugar is The Deoxyribose (has just an Deoxyribose hydrogen in the same place--- H) hydrogen H) Deoxy = “minus oxygen” DNA Nucleotides DNA Composition (3 parts): 1- Deoxyribose sugar (no O in 3rd carbon) carbon) 2- Phosphate group 3- One of 4 types of bases (all 3- One containing nitrogen): - Adenine Adenine - Thymine (Only in DNA) Thymine - Cytosine - Guanine RNA Nucleotides RNA Composition ( 3 parts): 1- Ribose sugar (with O in 3rd carbon) 12- Phosphate group 3- One of 4 types of bases (all 3- One containing nitrogen): - Adenine Adenine - Uracyl (only in RNA) Uracyl - Cytosine - Guanine DNA vs RNA RNA DNA 1- Deoxyribose sugar 12- Bases: Adenine, Thymine, Cytosine, 2Thymine Cytosine, Guanine Guanine 3- Double-stranded helix arrangement 3- Double RNA 1- Ribose sugar 12- Bases: Adenine, Uracyl, Cytosine, 2Uracyl Cytosine, Guanine Guanine 4- Single stranded 4- Single The Double Helix (DNA) The Structural model: Model proposed by Watson & Crick, 1953 Two sugar-phosphate strands, next to each Two other, but running in opposite directions. other, Specific Hydrogen bonds occur among bases from one chain to the other: bases A---T , C---G A---T C---G Due to this specificity, a certain base on one Due strand indicates a certain base in the other. strand The 2 strands intertwine, forming a doublehelix that winds around a central axis How DNA Works How 1­ DNA stores genetic information in DNA segments called genes genes 2- The DNA code is in Triplet Codons 2Tri (short sequences of 3 nucleotides each) each) 3- Certain codons are translated by the 3codons cell into certain Amino certain acids. 4. Thus, the sequence of nucleotides in 4. sequence DNA indicate a sequence of Amino acids in a protein. acids protein ...
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