Term
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Definition
chromosome is displaced toward one end
(long arm + short arm) |
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Term
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Definition
centromere is neer one end
(long arm + knob) |
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Term
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Definition
| centromere at or very near the end of the chromosome |
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Term
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Definition
centromere located in the middle of the chromosome
(two arms of equal length) |
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Term
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Definition
| variations in the number and structure of chromosomes |
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Term
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Definition
| the complete set of chromosomes possessed by an organism |
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Term
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Definition
| areas of DNA rich in adenine-thymine (A-T) |
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Term
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Definition
| relative amounts of cytosine-guanine and adenine-thymine base pairs (C-G):(A-T) |
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Term
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Definition
| regions of DNA occupied by centromeric heterochromatin |
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Term
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Definition
| rich in cytosine-guanine base pairs (C-G) |
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Term
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Definition
alter the number of chromosomes
(one or more entire chromosome is added or deleted) |
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Term
| Chromosome rearrangements |
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Definition
| alter the structure of individual chromosomes (deletion or inversion) |
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Term
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Definition
one or more complete sets of chromosomes is added
(adding a complete chromosome to all chromosomes present) |
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Term
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Definition
| part of a chromosome has been doubled |
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Term
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Definition
| when the duplicated region is immediately adjacent to the original segment |
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Term
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Definition
| when the duplicated region is located some distance from the original segment |
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Term
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Definition
| when the duplication is inverted |
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Term
| What happens when there is heterozygous duplication? |
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Definition
| The two chromosomes are no longer homologous, and therefore cannot pair up during meiosis. This causes the longer chromosome to loop and twist so that the regions are able to line up. |
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Term
| CC1: Why do chromosomes often result in abnormal phenotypes? |
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Definition
| developmental processes depend on the relative amounts of proteins encoded by different genes (gene dosage) |
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Term
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Definition
| the loss of a chromosome segment |
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Term
| What happens if a deletion includes the centromere? |
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Definition
| the chromosome will not segregate in meiosis/mitosis and most likely become lost |
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Term
| Three reasons individuals heterozygous for deletion may have multiple defects? |
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Definition
(1) imbalances in the amounts of gene products
(2) pseudodominance
(3) haploinsufficient genes |
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Term
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Definition
the expression of a recessive mutation
indication that one of the homologous chromosomes has been deleted
produced when the wild-type allele in a heterozygous individual is absent due to a deletion on one chromosome |
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Term
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Definition
| when a single copy of a gene is not sufficient to produce a wild type phenotype |
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Term
| What typeof rearrangement is cri-du-chat syndrome and what chromosome is it located on? |
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Definition
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Term
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Definition
| three copies of chromosome 21 - trisomy/Aneuploidy |
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Term
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Definition
| when a chromosome segment is turned 180 degrees |
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Term
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Definition
| inversions that do not include the centromere |
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Term
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Definition
| inversions that do include the centromere |
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Term
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Definition
| if a genes position is altered by an inversion, they be expressed at inappropriate times or in inappropriate tissues |
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Term
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Definition
| one of the four chromatids has two centromeres |
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Term
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Definition
| when a chromosome lacks a centromere |
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Term
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Definition
Normally, in anaphase I, the centromeres are pilled toward opposite poles and the two homologous chromosomes separate.
However, in this case, the dicentric chromatid is stretched across the center of the nucleus, forming the dicentric bridge. This bridge eventually breaks as the chromosomes are pulled far enough apart. |
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Term
| paracentric inversion and crossing over |
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Definition
| no recombinant progeny will result when crossing over takes place because the recombinant gametes are not visible and therefore not observed |
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Term
| CC3: A dicentric chromosome is produced when crossing over takes pace in an individual heterozygous for which type of chromosome rearrangement? |
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Definition
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Term
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Definition
| a group of genetic traits which have high fitness when they occur together, but which without each other have low fitness |
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Term
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Definition
| the movements of genetic material between non homologous chromosomes or within the same chromosome |
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Term
| nonreciprocal translocation |
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Definition
| movement from one chromosome to another (but no reciprocated movement back to that chromosome) |
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Term
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Definition
| two-way exchange of segments between two non homologous chromosomes |
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Term
| Two ways translocations can affect phenotypes |
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Definition
(1) by causing genes to move to new locates where they come under the influence of new regulatory sequences
(2) by breaking genes and disrupting their functions |
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Term
| robertsonian translocation |
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Definition
when the long arms of two acrocentric chromosomes join to a common centromere through translocation
the outcome of this is one metacentric chromosome and one chromosome with two very short arms |
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Term
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Definition
| change in the number of individual chromosomes |
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Term
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Definition
| constrictions or gaps at particular locations that are prone to breakage under certain conditions |
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Term
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Definition
| change in the number of chromosome sets |
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Term
| Three ways that aneuploidy can arise |
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Definition
(1) lost in the course of mitosis/meiosis due to a loss of a centromere
(2) small chromosome generated by a Robertsonian translocation is lost
(3) nondisjunction |
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Term
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Definition
the failure of homologous chromosomes or sister chromatids to separate in meiosis/mitosis
leads to some gametes/cells with extra chromosomes and some with missing chromosomes |
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Term
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Definition
the loss of both members of a homologous pair of chromosomes
2n-2 |
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Term
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Definition
the loss of a single chromosome
2n-1 |
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Term
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Definition
the gain of a single chromosome
2n+1 |
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Term
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Definition
the gain of two homologous chromosomes
2n+2 |
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Term
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Definition
| arises form random nondisjuntion in egg formation, resulting in an extra copy of chromosome 21 (trisomy) |
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Term
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Definition
| when a person has the normal 46 chromosomes, however they have an extra copy of part of chromosome 21 attached to another chromosome through translocation |
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Term
| translocation carries >> Familial Down Syndrome |
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Definition
| people who contain only 45 chromosomes due to a Robersonian translocation of chromosomes 21 and 14. they obtain two copies of the long arms of both 21 and 14, and because the short arms carry nonessential genetic information it goes undetected |
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Term
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Definition
| genetic regulatory mechanism which operates to equalize the phenotypic expression of characteristics determined by genes on the X chromosome so that they are equally expressed in the human XY male and the XX female |
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Term
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Definition
when both chromosomes are inherited from the same parent
could origionate from tiresome, then a chromosome is lost in early development, and the two remaining chromosomes turn out to be from the same parent |
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Term
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Definition
(1) due to deletion of chromosome 15
(2) due to both chromosomes being inherited from one parent |
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Term
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Definition
a condition in which regions of tissue within a single individual have different chromosome constitutions
(areas where every cell has chromosome abnormalities and areas where no cells have chromosome abnormalities) |
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Term
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Definition
| an individual organism that is a mosaic for the sex chromosomes, possessing rises with different sex-chromosomes constitutions |
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Term
triploids
tetraploid
pentaploid |
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Definition
polyploid with 3n
polyploid with 4n
polyploid with 5n |
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Term
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Definition
| when there are extra sets of chromosomes and all chromosome sets are from a single species |
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Term
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Definition
| the hybridization of chromosome sets are from two or more species |
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Term
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Definition
a gamete that has a variable number go chromosomes
some may be missing and some may be present in more than one copy |
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Term
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Definition
| a type of allopolypoid consisting of two combined diploid genomes |
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