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15 Cards in this Set
- Front
- Back
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Define:
Transcription |
The process by which RNA is synthesized using a DNA template, thereby transferring genetic information from the DNA to the RNA.
Transcription is catalyzed by RNA polymerase as facilitated by numerous other proteins. |
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Define:
Translation |
The process of transforming the information contained in the nucleotide sequences of an RNA to the corresponding amino acid sequence of a polypeptide as specified by the genetic code.
Translation is catalyzed by ribosomes and requires the additional participation of messenger RNA (mRNA), transfer RNA (tRNA), and a variety of protein factors |
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Define:
Supercoiling |
The topological state of covalently closed circular double-helical DNA in which the double helix is twisted around itself. It arises through the over- or underwinding of the double helix.
Also called: Superhelicity |
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Define:
Linking number (L) |
The number of times that one strand of a covalently closed circular double-stranded DNA winds around the other; it cannot be changed without breaking covalent bonds.
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Define:
Twist (T) |
The number of complete revolutions that one strand of a covalently closed circular double-helical DNA makes around the duplex axis. It is positive for right-handed superhelical coils and negative for left-handed superhelical coils.
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Define:
Writhing number (W) |
The number of turns that the duplex axis of a covalently closed circular double-helical DNA makes around the superhelix axis. It is a measure of the DNA's superhelicity.
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Define:
Topoisomerase |
An enzyme that alters DNA supercoiling by catalyzing breaks in one or both strands, passing DNA through the break, and resealing the break.
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Define:
Hyperchromic effect |
The increase in DNA's ultraviolet absorbance resulting from the loss of stacking interactions as the DNA denatures.
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Define:
Melting temperature (Tm) |
The midpoint temperature of the melting curve for the thermal denaturation of a macromolecule.
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Define:
Chromosome |
The complex of protein and a single DNA molecule that comprises some or all of an organism's genome.
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Define:
Chromatin |
The complex of DNA and protein that comprises the eukaryotic chromosomes.
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Define:
Histones |
Highly conserved basic proteins that constitute the protein core to which DNA is bound to form a nucleosome.
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Define:
Nucleosome |
The complex of a histone octamer and ~200 bp of DNA that forms the lowest level of DNA organization in the eukaryotic chromosome.
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Define:
Nucleosome core particle |
The complex of histones and ~146 bp of DNA that forms a compact disk-shaped particle in which the DNA is wound in ~2 helical turns around the outside of the histone octamer.
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Define:
30-nm fiber |
A condensed chromatin structure in which nucleosomes fold in a zigzag manner to form a fiber with a diameter of ~30 nm.
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