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38 Cards in this Set
- Front
- Back
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RNA World Hypothesis |
The hypothesis that chemical evolution led to the existence of an RNA molecule that could make a copy of itself. Chance errors in the copying process created variations that would undergo natural selection. |
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Nucleic Acid |
A macromolecule composed of nucleotide monomers. Generally used by cells to store or tansmit hereditary information. Includes RNA and DNA. |
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Nucleotides |
A molecule consisting of one or more phosphate groups bonded to a 5-carbon sugar which is bonded to one of several nitrogen-containing bases. Nucleotides containing ribose are used as monomers to make RNA; those containing deoxyribose make DNA. Some perform additional roles in energy storage and signal transduction. |
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Sugar |
Also called a carbohydrate, though usually refers to small carbohydrates like monosaccharides and disaccharides. |
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Nucleotide Structure |
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Ribose Structure |
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Deoxyribose Structure |
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Purines |
A class of small, nitrogen-containing, double ringed bases (guanine and adenine) found in nucleotides. |
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Pyrimidines |
A class of small, nitrogen-containing, single-ringed bases (cytosine, uracil, thymine) found in nucleotides. |
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Ribonucleotides |
A, G, C, U |
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Deoxyribonucleotides |
A, G, C, T |
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When do nucleic acids form? |
When nucleotides polymerize. |
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Phosphodiester Linkage |
Chemical linkage between adjacent nucleotides in RNA and DNA. Forms when the phosphate group of one nucleotide condenses with the hydroxyl group on the sugar of another nucleotide |
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Ribonucleic Acid |
RNA. A nucleic acid composed of ribonucleotides that usually is single stranded and functions as structural components of ribosomes (rRNA), transporters of amino acids (tRNA), and translators of the message of the DNA code (mRNA). |
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Deoxyribonucleic Acid |
DNA. A nucleic acid composed of deoxyribonucleotides that carries the genetic information of a cell. Generally occurs as two intertwined strands, but these can be separated. |
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Direction of the sequence of bases in an RNA or DNA strand |
Always written in the 5' to 3' direction. Bases are added at the 3' end of a growing molecule. |
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Phosphorylation |
The addition of a phosphate group to a molecule. This raises the potential energy of substrate molecules enough to make an otherwise endergonic reaction possible. |
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Nucleoside |
A molecule consisting of a 5-carbon sugar (ribose or deoxyribose) and one of several nitrogen-containing bases. |
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Nucleotides used to make RNA |
ATP, CTP, GTP, and UTP |
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Nucleotides used to make DNA |
dATP, dCTP, dGTP, and dTTP |
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Nucleus |
In eukaryotic cells, the large organelle containing the chromosomes and surrounded by a double membrane. Most DNA and RNA synthesis occurs here. |
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Gel Electrophoresis |
A technique for separating molecules on the basis of size and electric charge, which affect their differing rates of movement through a gelatinous substance in an electric field. |
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How is the secondary structure of nucleic acids formed? |
By hydrogen bonding between nitrogenous bases. |
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X-ray Crystallography |
A technique for determining the three-dimensional structure of large molecules, including proteins and nucleic acids, by analysis of the diffraction patterns produced by X-rays beamed at crystals of the molecule. |
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What was Watson and Crick's model for DNA's secondary structure based off of? |
1. DNA has a sugar-phosphate backbone 2. From Chargaff: number of purines = number of pyrimidines and number of T's and A's = number of C's and G's 3. From Franklin and Wilkins: the pattern from x-ray crystallography indicated a helix shape |
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Antiparallel |
Describing the opposite orientation of the strands in a DNA double helix with one strand running in the 5' to 3' direction and the other in the 3' to 5' direction. |
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Complementary Base Pairing |
The association between specific nitrogenous bases of nucleic acids stabilized by hydrogen bonding. Adenine pairs only with thymine or uracil and guanine pairs only with cytosine. A-T forms two H bonds (so does A-U) and G-C form three H bonds, so the G-C interaction is stronger. |
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Watson-Crick Pairing |
Interchangeable with complementary base pairing. |
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DNA two dimensional diagram and explanation |
The tight packing of nitrogenous bases creates a hydrophobic interior that is hard to break. But, the whole molecule is hydrophilic. |
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Why does the twisting occur in DNA? |
To allow the nitrogenous bases to line up in a way that lets them hydrogen bond. |
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Base Pair (BP) |
A pair of nucleotides found in a double-stranded DNA molecule. Used as a unit of length. |
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Steps in copying DNA |
1. Separation: occurs when the hydrogen bonds break 2. Base pairing: free nucleotides attach to the 3' ends. 3. Polymerization: the new strands polymerize to form the backbone and secondary structure is restored. |
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Template Strand |
An original strand of RNA used to make a complementary strand of RNA. |
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Levels of Structure in DNA |
Primary: Sequence of deoxyribonucleotides, bases are A,T,G,C Secondary: Two antiparallel strands twist into a double helix, stabilized by H bonding between bases and hydrophobic interactions |
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Levels of Structure in RNA |
Primary: Sequence of ribonucleotides, bases are A,U,G,C Secondary: Commonly hairpins, formed when a single strand folds back on itself to form a double-helix stem and a single-stranded loop Tertiary: Folds form distinctive 3D shape Quaternary: Associations between several RNA molecules |
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RNA Diagram |
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Hairpin |
A secondary structure in RNA made of a stable loop formed by hydrogen bonding between purine and pyrimidine bases on the same strand. The formation of hairpins is exergonic because the energy released in the formation of H bonds makes the process favourable. |
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Ribozyme |
Any RNA molecule that can act as a catalyst. |
