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CHM 140
Ch 25
| Question | Answer |
|---|---|
| anticodon- | 3 nucleic acid sequents on t-RNA which is specific for each amino acids to be added to the protein chain in protein synthesis |
| codon- | 3 nucleic acid sequence on m-RNA which codes fro each amino acid. |
| gene- | DNA segment that codes for 1 protein |
| exon- | section of DNA that, when transcribed, codes for a protein or RNA |
| replication- | reproduction of DNA molecule into 2 new DNA molecules |
| A nucleotide consists of what 3 parts? | base, monosaccharide, phosphate |
| Name the 3 nucleotides that are derviative of pyrimidine. | cytidine, uridine, thymidine |
| Name the 2 nucelotides that are derivatives of purine. | Adenosine, Guanosine |
| In what nucleotide form is energy stored? | ATP adenosine 5’-triphosphate |
| What is the secondary structure of DNA? | Double helix: a type of 2° structure of DNA molecules in which two antiparallel polynucleotide strands are coiled in a right-handed manner about the same axis |
| What are the 3 differences between DNA and RNA? | DNA bases are A, G, C, and T; the RNA bases are A, G, C, and U pairs in DNA G-C, A-T in RNA G-C, A-U sugar in DNA is 2-deoxy-D-ribose; in RNA it is D-ribose 3)DNA double stranded; RNA single-stranded |
| What are the 3 main types of RNA? What is the function of each? | 1)m-RNA:directs amino acid sequence of proteins 2)t-RNA:transports amion acids to the site of protein synthesis 3)r-RNA:combines with proteins to form ribosomes |
| translation- | Protein synthesis |
| Describe steps 1-4 in protein synthesis. | 1. mRNA transcribed from DNA strand in nucleus goes ribsome, attaches 30S unit at P & A sites 2. Methionyl-tRNA binds to P site through a codon-anticodon interaction. 3.50S ribosomal unit attaches 30S unit. 4. Anticodon of 2nd tRNA binds w/next codon mRNA |
| Describe steps 5-8 in protein synthesis. | 5. Amino acid in P site joined to amino acid on A site via peptide bond. 6. 1st tRNA leaves ribosome. 7. Ribosome moves along mRNA chain one codon unit. 8. Steps 4 through 6 are repeated until protein is synthesized. |
| Describe structure of nucleosome | core of 8 histone molecules which the DNA helix is wrapped around |