Chromosome Mutations: Variation in Chromosome Number and Arrangement Flashcards
Specific Terminology Describes Variations in Chromosome Number:
• Aneuploidy
• Euploidy
• Polyploidy
______, the Loss of a Single Chromosome, May Have Severe Phenotypic Effects
Monosomy
______ Involves the Addition of a Chromosome to a Diploid Genome
Trisomy
Trisomy (2n + 1 chromosomes) for the ______ has a less dramatic phenotype than trisomies for ______, which are often lethal.
sex chromosomes, autosomes
______ results from trisomy of chromosome 21.
Down syndrome
______ are often found in spontaneously aborted fetuses, but ______ are not.
This suggests that ______ gametes may be functionally impaired.
Trisomies, monosomies, monosomic
______, in Which More Than Two Haploid Sets of Chromosomes Are Present, Is Prevalent in Plants
Polyploidy
The naming of polyploids is based on the number of sets of chromosomes found:
triploid
tetraploid
pentaploid
The naming of polyploids is based on the number of sets of chromosomes found:
• a ______ has 3n chromosomes
triploid
The naming of polyploids is based on the number of sets of chromosomes found:
• a ______ has 4n chromosomes
tetraploid
The naming of polyploids is based on the number of sets of chromosomes found:
• a ______, 5n chromosomes
pentaploid
Polyploidy can originate by:
autopolyploidy
allopolyploidy
Polyploidy can originate by:
• the addition of one or more sets of chromosomes identical to the haploid complement of the same species (______)
autopolyploidy
Polyploidy can originate by:
• or the combination of chromosome sets from different species as a consequence of interspecific matings (______)
allopolyploidy
Variation Occurs in the ______ and ______ of Chromosomes
Internal Composition, Arrangement
Rearrangements of chromosome segments include:
• deletions
• duplications
• inversions
• nonreciprocal translocations
• reciprocal translocations
A ______ Is a Missing Region of a Chromosome
Deletion
When a chromosome breaks in one or more places and a portion of it is lost, the missing piece is referred to as a ______ (or a ______).
deletion, deficiency
The deletion can occur:
terminal deletion
intercalary deletion
The deletion can occur:
• near one end (______)
terminal deletion
The deletion can occur:
• from the interior of the chromosome (______)
intercalary deletion
______ results from a segmental deletion of a small terminal portion of the short arm of chromosome 5
Cri-du-chat
The type of Notch phenotypic expression of recessive genes in association with a deletion in Drosophila is an example of ______.
pseudodominance
A ______ Is a Repeated Segment of the Genetic Material
Duplication
______ arise as the result of unequal crossing over during meiosis or through a replication error prior to meiosis.
Duplications
Organisms have multiple copies of the ______ genes (______).
This is an example of ______.
ribosomal RNA, rDNA, gene redundancy
______ is another mechanism to increase the rRNA.
Gene amplification
The ______ phenotype in Drosophila results from duplication.
Bar-eye
______ Rearrange the Linear Gene Sequence
Inversions
An ______ involves a rearrangement of the linear gene sequence rather than the loss of genetic information.
inversion
In an ______, a segment of a chromosome is turned around 180° within a chromosome.
inversion
types of inversion:
Paracentric inversion
Pericentric inversion
Synapsis of inverted chromosomes requires an ______.
inversion loop
For a paracentric inversion crossover:
dicentric
acentric
For a paracentric inversion crossover:
• one recombinant chromatid is ______ (two centromeres)
dicentric
For a paracentric inversion crossover:
• one is ______ (lacking a centromere)
acentric
______ Alter the Location of Chromosomal Segments in the Genome
Translocations
______ - movement of a chromosomal segment to a new location in the genome.
Translocation
______ Translocation
• involves exchange of segments between 2 nonhomologous chromosomes
Reciprocal
______ Translocation
• has an unusual synapsis configuration during meiosis
Reciprocal
______ or ______ involves breaks at the extreme ends of the short arms of 2 nonhomologous acrocentric chromosomes
Robertsonian translocation, centric fusion
______ in Humans Are Susceptible to Chromosome Breakage
Fragile Sites
______ are more susceptible to chromosome breakage when cells are cultured in the absence of certain chemicals such as ______.
Fragile sites, folic acid
______ (______) is the most common form of inherited mental retardation, affecting about 1 in ______ males and 1 in ______ females, and is a ______ trait.
Fragile X syndrome, Martin–Bell syndrome, 4000, 8000, dominant
