Glossary D-H Flashcards
degeneracy
in molecular biology this term refers to the fact that multiple different codons may encode the same amino acid.
however, a given codon does not encode more than one amino acid within the nucleus of an organism
deletion
the absence of bases that are present in the wild-type DNA sequence
derepression
(see repression)
diploid
cells containing copies of both the maternal and paternal chromosomes
DNA
deoxyribonucleic acid
the molecular responsible for storing and transmitting genetic information
composed of 2 strands of nucleotides twisted around each other in the shape of a double helix
DNA gyrase
(see gyrase)
DNA ligase
enzymatic activity responsible for creating phosphodiester bonds between the 5’ end of one strand of DNA and the 3’ end of another strand
requires the presence of a 5’ phosphate on one strand, and a 3’ hydroxyl group on the second strand
DNA methylation
addition of methyl groups to the bases of DNA molecules
particular bases are methylated by specific DNA methylase enzymes
DNA polymerase
enzymatic activity responsible for catalyzing the polymerization of DNA.
Is dependent upon an annealed primer from which to initiate polymerization, and a DNA template from which to copy
domain
refers to a segment of a macromolecule that serves a specific function, either enzymatic, structural, or another specialized function
dominant allele
allele that determines phenotype in a heterozygous individual carrying another recessive allele
double helix
the helical shape assumed by DNA in which the two complementary strands hydrogen bond together in opposite orientations (i.e. have opposite polarities)
electrophoresis
a class of techniques wherein macromolecules are moved through a matrix using an electric current to effect their separation
elongation factor
a protein(s) that associates with the ribosome cyclically to assist in loading tRNA into the A site of the ribosome
endoplasmic reticulum
a specialized membranous organelle within eukaryotic cells responsible for synthesis of membrane-inserted proteins, and for producing proteins to be exported to the cell surface or beyond
enhancer
chromosomal sequences responsible for up-regulating the activity of an associated promoter
may function in either orientation, and may be upstream, downstream, or even embedded within an intron of the gene being regulated
epigenetic
a change in phenotype brought about by changes in gene regulation rather than by a change in genotype.
epigenetic influences are often heritable
episome
an extrachromosomal, non-organellar genetic element that is permanently maintained
epitope
a chemical structure capable of eliciting an immune cell response and of being specifically recognized by molecules of immune recognition (e.g. immunoglobulins, T-cell receptors, etc.)
exon
a contiguous segment of genomic DNA that is translated into polypeptide (see intron)
expressed
expression library
a type of library, constructed in an expression vector, that can be screened based on detection of a polypeptide product
such recombinant constructs do not necessarily produce full-length products, nor can they necessarily impart a new phenotype based on the cloned sequence
familial
(see inherited trait)
flow cytometry
method used to measure nuclear DNA quantity in order to determine ploidy status
frame-shift
a change from one reading frame to another
a type of mutation that results in a change in the reading frame used in the translation of a transcript
functional cloning (expression cloning)
A cloning strategy that uses a phenotypic screening method to identify the target gene.
Not to be confused to screening of an expression library.
fusion protein
A chimeric polypeptide comprised of sequences derived from more than one gene.
gDNA
shorthand for “genomic DNA”
gel electrophoresis
(see electrophoresis)
gene
a discrete unit of DNA (or RNA in some viruses) that encodes a nucleic acid or protein product that contributes to or influences the phenotype of the cell
gene conversion
a non-mendelian pattern of inheritance wherein one allele of a gene is modified with sequences originating from another allele, usually without modifying the second allele
gene dosage
refers to the number of copies of a given gene within the overall genome.
the term is often used in reference to situations where amplification of a gene has occurred, resulting in an altered phenotype of a cell or organism
gene superfamily
a large group of genes related (often poorly) by sequence homologies or by the structures of their products, and by their involvement in different species of the same larger process (eg immunoglobulin gene superfamily)
gene therapy
a technique involving the use of foreign genetic material to correct a genetic defect or to modify the phenotype of an affected individual, by targeting somatic cells
genetic disease
heritable genetic alterations from wild type which, when expressed, result in decreased viability of the individual receiving the altered gene(s)
genetic map
The ordering of genes by the statistical determination of recombination event between them.
Genes separated by greater distances are more likely to recombine.
genome
The entire compliment of permanently maintained nucleic acid containing the information necessary to encode the organism
genotype
the unique collection of genes (or gene alleles) present within an organism
germline
Tissues involved generation of haploid gametes
guanine
one of the purine bases found in DNA and RNA
2-amino-6-hydroxypurine
gyrase
an enzymatic responsible for maintaining supercoiling in DNA
haplotype
The particular combination of alleles present within a defined region of some chromosomes.
Originally was client to describe MHC antigens, but now is used to describe RFLP patterns and certain other situations
H-chain
immunoglobulin heavy chain
half-life (t1/2)
the period of time necessary for the loss or degradation of 50% of the activity or integrity of a molecule.
helicase
Enzymatic complexes that utilize the energy of ATP to drive unwinding of dsDNA during replication.
Heterochromatin
Highly condensed DNA and associated proteins that usually has a little transcriptional activity
Heterozygous
Individual content and dissimilar alleles for a given gene or locus
histones
Highly basic proteins which associate the chromosomal DNA to package it into a compact, higher order structure.
hnRNA
heterogeneous nuclear RNA
The highly size-heterogeneous RNA that is present in the nucleus due to the presence of a large variety of primary transcripts for different genes of different sizes and in various states of processing
Holoprotein
The complete, functional form of a protein that includes all its normally associated subunits and any necessary prosthetic groups
(also see Protein)
homeotic gene
a “master gene” that is responsible for the control of the defined set of numerous other genes, usually in developmental pathways.
homeotic mutation
a mutation in a homeotic gene that is responsible for controlling the activities of numerous other genes, usually during embryologic development in higher organisms
Homologues
genes found and different species that have the same genetic origin, and usually serve the same function
Homology
sequence homology
A term implying both overall sequence similarity and a common genetic origin between two (or more) sequences
Hybridization
the alignment of complementary strands of DNA (or RNA) from different sources via a base pairing
Widely used to identify portions of DNA on a Southern or (Northern) blot, using labeled probes
Hydrogen bond
A non-covalent attraction between a hydrogen atom of one molecule and an electron-withdrawing atom of a second molecule
