geneticstest3.txt

a chromosome without a centromere

mutation involving the accumulation of one or more nucleotide pairs

enzyme that methylates (adds -CH3 group) adenines before replication, thereby distinguishing old strands from the newly synthesized complementary strands of DNA

a polyploid individual formed from the union of two separate chromosome sets from two or more different species

this results when a dicentric chromosome is simultaneously dragged to opposite poles at anaphase These chromosomes typically will not be incorporated into either progeny cell

“Not euploid,” an individual whose chromosome number differs from the normal chromosome number; generally do not have viable offspring; for example in humans having Down's sydrome (trisomy 21) would be aneuploids

An enzyme that removes apurinic sites in DNA so that repair synthesis can replace them with appropriate complementary strands

A DNA site that has lost a purine residue (lose G or A)

individual with multiple chromosome sets originating from within one species, usually formed from the doubling of a single genome

Type of rearrangement where there is a change in the chromosomal gene order but no removal or duplication of DNA occurs (Inversions and reciprocal translocations)

A chemical whose molecular structure mimics that of a DNA base; because of the mimicry, the analog may act as a mutagen

One of several excision repair pathways In this pathway, subtle base-pair distortions are repaired by creation of apurinic sites followed by repair synthesis

subdiscipline of molecular biology interested in predicting the information content of nucleotide sequences

any type of change in the chromosome structure or number; these are large-scale mutations as opposed to gene mutations that are usually point mutations…

GACT substitution within a codon that leads to replacement of an amino acid with one of similar chemical properties

A mutation involving the removal of one or more nucleotide pairs OR a larger portion of a chromosome

A chromosome with two centromeres

Enzymes that remove altered bases, leaving apurinc sites

the molecular ATGC differences at a given location that occur between individuals of a species

The process in organisms using a chromosomal sex determination mechanism (XX vs XY) that allows standard structural genes on the sex chromosome to be expressed at the same levels in males and females, regardless of the number of sex chromosomes In mammals it operates by maintaining only a single active X chromosome in each cell

An abnormal phenotype including mental retardation, that is due to a trisomy of chromosome 21 caused by a nondisjunction; more common in babies born to older mothers

More than one copy of a particular chromosomal segment in a chromosome set

an individual with the basic number of chromosome sets, for example in humans we would expect 44 autosomes, 2 sex chromosomes for a diploid total of 46

works if only one side of the DNA helix is damaged, the repair of DNA lesion by removal of the faulty DNA segment and its replacement with a wild-type segment using the repair DNA synthesis system

The insertion or deletion of a nucleotide pair or pairs, causing a disruption of the translational reading frame

The relationship between the number of copies of a gene and the amount of the gene’s product made, i.e. the more copies of the gene, the more transcripts are produced and the more of the corresponding protein is made

study of the gene organization, protein families, biochemical pathways, developmental regulation, gene regulation for ALL expressed transcripts and/or polypeptides of an organism

partially homologous chromosome sets, these are found in allopolyploids

a shortcut to say both insertion and deletion mutations

a mutation that occurs after mutagen (environmental agent) treatment

A mutagen that can insert itself between the stacked bases at the center of the DNA double helix, causing an elevated rate of indel mutations

A small deletion WITHIN a gene

The paired homologs in inversion heterozygotes form a loop because one chromosome twists once at the ends of the inversion to pair with the untwisted chromosome

A chromosomal mutation consisting of the removal of a chromosome segment, its rotation through degrees, and its reinsertion in the same location (Reversing the segment)

Combination of XXY chromosomes (extra X chromosome) These persons are males with lanky build, with some developmental abnormalities, and usually are sterile

A large set of cloned DNA molecules spotted onto a solid matrix (such as a microscope slide) for use in probing a biological sample for example, to monitor gene expression

variable numbers of dinucleotides repeated in tandem, most common is CA on one strand and GT on the complementary strand

based on units of 15-100 bases repeated to lengths of 1000-5000 base pairs long scattered throughout the human genome

A repair system for repairing damage to DNA that has already been replicated

general term for nucleotide substitution within a protein-coding region that changes the codon to specify another amino acid

An individual of a normally diploid species that has only one chromosome set (n) Examples include male bees, wasps, and ants

(monosomic, 2n-1 in diploids) a cell or individual that is basically diploid but that has only one copy of one particular chromosome type, for example Turner's syndrome is monosomy X (XO)

larger deletions in a chromosome across more than one genetic locus with more severe consequences than intragenic deletions

an environmental agent which increases the mutation rate, examples include viruses, UV light, radiation, X rays, some chemicals!

as simple as the change of one base pair from what was expected, can include small or large scale additions, deletions or rearrangements of chromosomes

variation in DNA sequences, those GATC's, from one individual of a species to another, usually in the wobble position. Current estimates show 1 variation every 1000 base pairs in human individuals, so just 3 million base changes separates you from your neighbor!

GACT substitution in a codon that leads to replacement of an amino acid with one of different chemical properties

The failure of homologs (at meiosis) or sister chromatids (at mitosis) to separate properly to opposite poles

GACT substitution within a protein-coding region that changes a codon for an amino acid into a termination codon

An excision-repair pathway that breaks the phosphodiester bonds on either side of the damaged base, removing that base and several on either side, this is followed by repair DNA synthesis to fill in the gap

(nullisomy, 2n-2 in diploids) a cell or individual with one chromosomal type missing, there are no examples of diseases in humans with a total loss of both homologous chromosomes!

one origin of spontaneous DNA damage due to reactive oxygen chemicals like hydrogen peroxide, yields a high level of G to T transversions

a type of inversion where the centromere is outside of the inversion

the production of offspring by a female with no genetic contribution from the male, the unfertilized egg can develop into an embryo without being fertilized (found in male bees, wasps and ants!)

a type of inversion that spans the centromere

an enzyme that cleaves thymine dimers

a complete series of clones that are sequenced to generate the entire sequence of GATC's for all or part of a chromosome (telomere to telomere!)

mutation that can be mapped to one specific locus

these are ABERRANT EUPLOID individual organisms in which there are more than two chromosome sets, triploid (3n), tetraploid (4n), etc. Especially found in plants that are VIABLE and produce viable offspring!

the sudden appearance of a recessive due to deletion of a masking dominant gene

apparent linkage of genes that are normally on separate nonhomologous chromosomes A diagnostic clue to the presence of a translocation

randomly amplified polymorphic DNA, using PCR primers with a "random" set of GATC's to amplify several different genome regions

changes in chromosome structure that include changes such as deletion, duplication, inversion, and translocation

the repair of a DNA lesion through a process, similar to recombination

restriction fragment length polymorphism, some individuals will have a site where a restriction enzyme cuts their DNA, other individuals will not have this same site

single nucleotide polymorphisms, usually due to neutral variation in the wobble position, the individual GATC differences in two genomes between two individual of the same species

an emergency response and error-prone process whereby gross structural DNA damage is bypassed by inserting nonspecific bases using some of the DNA replication enzymes

a mutation occurring WITHOUT exposure to mutagens, also known as the background rate of mutation usually due to errors of DNA duplication

simple sequence length polymorphisms, or variation in short repeats that has replaced RFLP for DNA fingerprinting since most genomes have more variation in SSLP than RFLP markers

GATC substitition in a codon that does not change the amino acid brought to the ribosome, also called silent mutaitons or neutral variation

description of DNA segments in which the gene order is identical in different related species

the spontaneous isomerization of a nitrogen base from its normal keto form an alternative hydrogen-bonding enol form

a type of nucleotide substitution involving the replacement of a purine with another purine (G to A or A to G) or of a pyrimidine with another pyrimidine (C to T or T to C)

the relocation of a chromosomal segment in a different position in the genome

a type of nucleotide substition where a pyridine replaces a purine or the reverse, so C to A or C to G or A to T, etc.

the expansion of a base pair repeat from a relatively low number of copies to a high number of copies that is responsible for a number of genetic disease, such as Huntington’s disease

(trisomic, 2n+1 in diploids) a cell or individual that is basically a diploid with an extra chromosome of one type, for example Down's syndrome with trisomy 21

a rearrangement of chromosome parts that changes the gene dosage of a part of the affected chromosome (Deletions and duplications)

variable number of tandem repeats, in humans a stretch of GATC's from 15-100 base pairs long that are repeated to lengths of 1-5 kb

attempt to understand the organization and base sequences of all the DNA in an organism (for humans this means mapping all 23 chromosomes plus the mitochondria's DNA)

part of the dosage compensation in mammals where the second X chromosome in a FEMALE mammal is not used for transcription