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Biology chapt 12
Biology chapter 12
Term | Definition |
---|---|
adenine (A) | One of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA. Pairs with uracil (U) and thymine (T). |
guanine (G) | One of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA; pairs with cytosine. |
thymine (T) | One of four nitrogen-containing bases in nucleotides composing the structure of DNA; pairs with adenine. |
cytosine (C) | One of four nitrogen-containing bases in the nucleotides composing the structure of DNA and RNA; pairs with guanine. |
double helix | Double spiral; describes the threedimensional shape of DNA. |
complementary base pairing | Hydrogen bonding between particular purines and pyrimidines; responsible for the structure of DNA, and some RNA, molecules. |
DNA replication | Synthesis of a new DNA double helix prior to mitosis and meiosis in eukaryotic cells and during prokaryotic fission in prokaryotic cells. |
template | Parental strand of DNA that serves as a guide for the complementary daughter strand produced during DNA replication. |
semiconservative replication | Process of DNA replication that results in two double helix molecules, each having one parental and one new strand. |
DNA helicase | Enzyme unwinds DNA and separates the parental stands. |
String-standed binging proteins (SSB) | Attach to newly seprated DNA and prevent it form re-forming tha helix so replication can occur. |
DNA Primase | Places short primers on the strands to be replicated. |
DNA ligase | Enzyme that links DNA fragments; used during production of recombinant DNA to join foreign DNA to vector DNA. |
replication fork | In eukaryotic DNA replication, the location where the two parental DNA strands separate. |
uracil (U) | Pyrimidine base that occurs in RNA, replacing thymine. |
messenger RNA (mRNA) | Type of RNA formed from a DNA template and bearing coded information for the amino acid sequence of a polypeptide. |
transfer RNA (tRNA) | Type of RNA that transfers a particular amino acid to a ribosome during protein synthesis; at one end it binds to the amino acid, and at the other end it has an anticodon that binds to an mRNA codon. |
ribosomal RNA (rRNA) | Structural form of RNA found in the ribosomes. |
transcription | First stage of gene expression; process whereby a DNA strand serves as a template for the formation of mRNA. |
translation | During gene expression, the process whereby ribosomes use the sequence of codons in mRNA to produce a polypeptide with a particular sequence of amino acids. |
central dogma | Processes that dictate the flow of information from the DNA to RNA to protein in a cell. |
genetic code | Universal code that has existed for eons and allows for conversion of DNA and RNA’s chemical code to a sequence of amino acids in a protein. Each codon consists of three bases that stand for one of the 20 amino acids found in proteins. |
triplet code | During gene expression, each sequence of three nucleotide bases stands for a particular amino acid |
codon | Three-base sequence in messenger RNA that during translation directs the addition of a particular amino acid into a protein or directs termination of the process. |
rNA polymerase | During transcription, an enzyme that creates an mRNA transcript by joining nucleotides complementary to a DNA template. |
promoter | In an operon, a sequence of DNA where RNA polymerase binds prior to transcription. |
mRNA transcript | mRNA molecule formed during transcription that has a sequence of bases complementary to a gene. |
exon | Segment of mRNA containing the proteincoding portion of a gene that remains within the mRNA after splicing has occurred. |
intron | Intervening sequence found between exons in mRNA; removed by RNA processing before translation. |
ribozyme | RNA molecule that functions as an enzyme that can catalyze chemical reactions. |
anticodon | Three-base sequence in a transfer RNA molecule base that pairs with a complementary codon in mRNA. |
polyribosome | String of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis. |
initiation | First stage of translation in which the translational machinery binds an mRNA and assembles. |
elongation | Middle stage of translation in which additional amino acids specified by the mRNA are added to the growing polypeptide. |
termination | End of translation that occurs when a ribosome reaches a stop codon on the mRNA that it is translating, causing release of the completed protein. |
proteomics | Study of the complete collection of proteins that a cell or organism expresses. |