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Biology 1402
Test 2 Part 2
44
Biology
Undergraduate 1
03/12/2008

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Term
pyrimidine
Definition
one of two families of nitrogeneous bases found in nucleotides - cytosine, thymine
Term
purines
Definition
one of two families of nitrogeneous bases in nucleotides- adenine guanine
Term
DNA
Definition
the genetic material that organisms inherit from their parents; a double stranded, helical macromolecule consisting of nucleotide monomers with deoxyribose sugar and the nitrogenous bases adenine (A) and guanine (G) and Thymine (T)
Term
RNA
Definition
A type of nucleic acid consisting of nucletide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), Guanine (G), and Uracil (U); usually single stranded; fuctions in protein synthesis and as the genome of some viruses
Term
double helix
Definition
the form of native DNA, referring to its two adjacent polynucleotide stands wound up into a spiral shape
Term
transcription
Definition
the synthesis of RNA on a DNA template
Term
translation
Definition
the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of "language" from nucleotides to amino acids
Term
DNA polymerase
Definition
an enzyme that assembles DNA nucleotides into polynucleotides  using a preexisting strand of DNA as a template
Term
RNA polymerase
Definition
an enzyme that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template
Term
ribosome
Definition
a cell organelle consisting of RNA and protein organized into two subunits and functioing as the site of protein synthesis in the cytoplasma. The ribosomal subunits are constructed in the nucleolus
Term
promoter
Definition
a specific nucleotide sequence in DNA, located at the start of a gene, that is the binding site for RNA polymerase and the place where transcription begins
Term
terminator
Definition
a special sequence of nucleotides in DNA that marks the end of gene. It signals RNA polymerase to release the newly made RNA molecule, and then to depart from the gene
Term
triplet code
Definition
a set of three-nucleotide--long words that specify the amino acids for polypeptide chains
Term
codon
Definition
a three-nucleotide sequence in mRNA that specifies a specific amino acid or plypeptide termination signal-the basic unit of the genetic code
Term
anticodon
Definition
on a tRNA molecule, a specific sequence of three-nucleotides that is complimentary to a codon triplet on mRNA
Term
mRNA
Definition
messenger RNA - the type of ribonucleic acid that encodes genetic info. from DNA and conveys its ribosomes, where the information is translated into amino acid sequences
Term
tRNA
Definition
transfer RNA - a type of ribonucleic acid that functions as an interpreter in translation. Each tRNA molecule has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA
Term
rRNA
Definition
the type of ribonucleic acid that, together with proteins, makes up ribosomes; the most abundant type of RNA (ribosomal)
Term
mutation
Definition
a change in the nucleotide sequence of DNA; the ultimate source of genetic diversity
Term
mutagen
Definition
a chemical of physical agent that interacts with DNA and causes a mutation
Term
gene expression
Definition
the process whereby genetic info. flows from genes to proteins; the flow of information from the genotype to the phenotype
Term
cellular differentiation
Definition
the specialization in the structure and function of cells that occurs during the development of an organism; results from selective activation and deactivation of the cell's genes
Term
operon
Definition
a unit of genetic regulation common in prokaryotes; a cluster of genes with related fucntions; aling with the promoter and operator that control their transcription
Term
operator
Definition
in prokaryotic DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach. the binding of repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon
Term
promoter
Definition
a specific nucleotide sequence in DNA; located at the start of a gene, that is the binding site for DNA plymerase and the place where transciption begins
Term
repressor
Definition
a protein that blocks the transcription of a gene or operon
Term
inducer
Definition
sugar molecule (lactose) which binds repressor proteins
Term
enhancer
Definition
a eukaryotic DNA sequence that helps stimulate the transcription of a gene at some distance from it; functions by means of a transcription factor called an activator, which binds to it and then to the rest of the transcription apparatus
Term
histone
Definition
a small protein molecule associated with DNA and important in DNA packing in the eukaryotic chromosome
Term
nucleosome
Definition
the bead-like unit of DNA packaging in a eukaryotic cell; consists of DNA wound around a protein core made up of eight histone molecules
Term
exon
Definition
in eukaryotes, a coding portion of a gene
Term
intron
Definition
in eukaryotes, a nonexpressed (noncoding) portion of a gene that is excised from the RNA transcript
Term
Benign Tumor
Definition
an abnormal mass of cells that remains at its original site in the body
Term
malignant tumor
Definition
an abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor
Term
metastasis
Definition
the spread of cancer cells beyond their original site
Term
oncogene
Definition
a cancer-causing gene; usually contributes to malignancy by abnormally enhancing the amount or activity of a growth factor made by the cell
Term
carcinogen
Definition
a cancer-causing agent; either high-energy radiation or a chemical
Term
RFLP's
Definition
restriction fragment length polymorphisms: the differences in homologous DNA sequences that are reflected in different lenths of restriction fragments produced when the DNA is cut up with restriction enzymes
Term
 PCR
Definition
Polymerase Chain Reaction - a technique used to obtain many copies of a DNA molecule; a small amount of DNA mized with the enzyme DNA polymerase, DNA Nucleotides, and a few other ingredients replicates repeatedly in a test tube
Term
DNA fingerprinting
Definition
a procedure that analyzes an individual's unique collection of DNA restriction fragments, detected by electrophoresis and nucleic acid probes; can be used to determine whether to samples of genetic material are from the same individual
Term
missense mutation
Definition
base substitution which converts one amino acid into another
Term
nonsense mutation
Definition
converts an amino acid into a stop codon, causing a truncated protein
Term
frameshift mutation
Definition
base insertion or deletion, which shifts the reading frame
Term
inducer
Definition
sugar molecule (lactose) which binds repressor protein
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