| What are nucleic acids? | macromolecules occur in all living things as well as viruses. Involved in carrying and expressing genetic information carried by sequences of 4 main nucleotides. |
| what are nucleotides? | characteristic to each gene. |
| Talk about the diversity of sequences? | because DNA molecules are long (thousands of nucleutide base pairs) there is an infinite number of sequences (4^n) . |
| How do nucleic acids occur? | deoxyribonucleic acids (DNA) and ribonucleic acids (RNA) |
| What are nucleic acids composed from? | unbranched chains of nucleotides |
| What are nucleotides composed from? | a nucleoside connected to one, two or three phosphate groups through C'5 of pentose (ribose). |
| What are nucleosides composed from? | a nitrogenous base (purine (guanine and adenine) or pyrimidine (cytosine, thymine or uracil)) and a pentose (ribose with OH in C'2 and deoxyribose H in C'2) they are named (genetics) and other minor or unusual nitrogenous bases have been identified in DNA and RNA. |
| How do RNA and DNA differ? | (1) C'2 in pentose (2) thymidine is replaced with uracil (3) secondary structure of DNA is double stranded whereas RNA is usually single stranded (4) DNA are more stable (5) DNA are only found in nucleus chloroplast or mitochondria whereas RNA are found all these compartments as well as the cytoplasm |
| How are molecules of nucleotide linked? | Covalently, N'1 of pyrimidine or N'9 of purine to C'1 of pentose through N-glycosidic bond, phosphoester bond between C'5 and P |
| How are nucleic acids polymerized? | they occur as nucleoside monophosphates, however nucleotides that serve as building blocs are nucleoside triphosphates. Two adjacent nucleotides are always joined by phosphodiester bond between C'5 and C'3 of each nucleotide, nucleotides lose one or two phosphate groups to supply required energy for the ester bonds. |
| Talk about the DNA structure | discovered by Watson and Crick, DNA are double helical polynucleotides wound around each other, and purines always face pyrimidines (A and T 2 H bonds C and G 3 H bonds) DNA has two complementary chains each strand has a backbone and nitrogenous bases.
the strands are antiparallel helix is 2nm in diameter, turn is 3.4 nm in length and two successive nucleotides are 0.34 nm apart, they may be B helix (water rich), A helix (poor water) or Z helix (vitro) (named according to major and minor grooves) |
| Why is DNA resistant to heating? | If DNA is heated to 90-100 C H bonds are broken causing untwisting of double helix strands separate but nucleotide sequences are still bonded, this process is called (DNA denaturation) and is reversible if temperature decreased progressively (renaturation) . Denaturation also occurs by increasing pH to become alkaline. |
| DNA replication? | semi-conservative, DNA polymerase is main functional protein, complementary strands |
| In tRNA where is the amino acid present? | 3' CCA |
| What is the least abundant RNA? Most abundant? | mRNA/rRNA |
| What is intramolecular pairing? | Ability of mRNA to fold back and form intramolecular interactions H-bonds |
| Describe tRNA structure. | trefoil structure with three loops, L shaped teriary structure. |
