BIOL 200 Lecture Notes - Lecture 2: Exact Sequence, Pyrimidine, Purine
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Rna + dna primary structures: linear polymers composed of monomers called nucleotides. Dna and mrna function primarily as informational molecules, carrying information in the exact sequence of their nucleotides. Large dna units in association with proteins can be visualized in the light microscope as chromosomes. Rna can function as a catalytic molecule. 3d conformations of dna and rna are different, which is critical to the diff functions of the two types of nucleic acids. A nucleic acid strand is a linear polymer with end-to-end directionality. In all organisms, dna and rna are each made up of only four different nucleotides. All nucleotides consist of an organic base linked to a five-carbon sugar that has a phosphate group attached to the 5" carbon. (in rna, the sugar = ribose. Purines (contain a pair of fused rings): adenine (a, guanine (g) Pyrimidines (contain a single ring): cytosine (c, thymine (t, uracil (u)
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Related Questions
QUESTION 1. Compared to eukaryotic genomes, only prokaryotic genomes:
A. contain DNA organized by histones. |
B. contain usually one, circular chromosome. |
C. contain plasmid DNA. |
D. have chromosomes contained in a nucleus. |
QUESTION 2. Azathioprine is a drug that may be prescribed to transplant recipients to reduce the chance of tissue rejection reactions. In its active state, it acts as a purine analogue, inhibiting DNA biosynthesis. This means that 6-mercaptopurine will be inserted in place of a purine containing nucleotides during DNA replication. Given this drug's mode of action, you would expect it to be incorporated into DNA in place of:
A. nucleotides containing guanine or cytosine. |
B. nucleotides containing adenine or thymine. |
C nucleotides containing adenine or guanine. |
D. nucleotides containing guanine nucleotide or uracil. |
QUESTION 3. RNA is distinguished from DNA because only RNA:
A. typically exists as a single-stranded molecule. |
B. has a 3' to 5' directionality. |
C. is composed of nucleotides that contain the sugar deoxyribose. |
D. is composed of nucleotides that contain the nitrogen bases T, C, G, and A. |
QUESTION 4. How are RNA nucleotides different from DNA nucleotides? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.
A. RNA nucleotides do not contain thymine. |
B. RNA nucleotides use the sugar ribose, while DNA nucleotides do not. |
C. RNA nucleotides lack phosphate. |
D. RNA nucleotides incorporate pyrimidine nitrogen bases, while DNA nucleotides only incorporate purine nitrogen bases. |