Variation in Chromosome Structure and # Flashcards
humans have _____ pairs of chromosomes.
Chimpanzees ____
Bonobos ______
23
24
24
Classification and identification of chromosomes: (3)
centromere postition
size
banding pattern
variation in chromosome structure–
deletion
duplication
inversion
translocation
missing region.
normal chromosome has broken in one or two places; or recombined at incorrect locations
deletion
region repeated.
crossover at misaligned sites on homologous chromosomes (recombination)
duplication
change in direction: 123—>321
inversion
segment becomes attached to a different part of the chromosome or to a different chromosome.
translocation
translocation simple: _________ _________ from a chromosome to another.
single piece
translocation–
_____________: exchange of pieces between different chromosomes.
reciprocal
_____________ tend to be detrimental .
deletions
Lejeune syndrome– which chromosome?
andelman syndrome–
prader-willi sysndrome–
5
15
15
_______________ tend to be less likely to have harmful effect than deletions.
ex: Charcot-Marie-Tooth disease (type 1A) what chromosome?
duplacations
15
Duplications can lead to ______ ______ _________ ( a segment of DNA—> 1000 bp with copy number differences among individuals of a species.
ex: humans–> schizophrenia, autism, susceptibility to _________ ___________.
copy number variation
infectious disease
____________ regularly no phenotypic consequences.
inversions
inversions:
- if its boundaries affected a gene, it probably leads to _____________ _________.
- ____________ _________- reposition of the gene in the chromosome (affects gene expression).
phenotypic effect
position effect
inversions are rare, surprisingly in humans, ___% of population carries detectable inversions.
2%
__________ __________: normal copy in one chromosome, inverted copy in the other (phenotypically normal)
inversion heterozygote.
____________ ___________: amount of genetic material in not altered, generally no phenotypic consequences.
balanced translocations
balanced translocations may result in ________ _________.
position effects
individuals with balanced translocations may have offspring with ______________ translocation: phenotypical abnormalities, some lethal.
unbalanced
______________ ___________: breaks near centromeres of two homologous acrocentric chromosomes
robertosonian translocation
segregation patterns in reciprocal translocations: a,b,c
a. diagonal chromosomes sort together
b. adjacent chromosomes of different centromeres sort together
c. chromosomes with same centromeres sort together (rare)
total of chromosomes in an exact multiple of chromosome set
euploid
three or more sets of chromosomes
polyploid
alteration in number of particular chromosomes; total not an exact multiple of n.
ex: trisomic (3 copies instead of 2), monosomic (1 instead of 2)
aneuploidy
aneuploidy usually causes abnormal phenotype, ____________ ________
detrimental effects
each chromosome may carry hundreds to thousands of genes
aneuploidy
excessive or deficient amounts of gene products
aneuploidy
- -variation in _______ in some animals are lethal (mammals)
- -________ ___________; male and female have different number of sets.
- -some morphologically similar species are found one as diploid and the other as __________
euploidy
haplodiploid species
polyploid
______________- polyploidy in cells or tissues in diploid organisms (ex: human liver cells, muscle cells, some species of Daphnia(crustaceans))
endopolyploidy
increase number of chromosome may enhance production of specific ________ ________ needed in great abundance
gene products
polytene chromosomes: giant chromosomes, caused by rounds of chromosome __________ without cellular division (ex: Drosophila salivary gland cells, ovary cells mosquitos, Phaseolus)
replication
variations in __________ are common in plants.
euploidy
ferns and flowering plants: _____-_____% are polyploids
30-35
important in agriculture: ___________ ________ display outstanding agricultural characteristics .
polyploid strains
plants with _____ number of sets tend to be sterile.
odd
odd number cannot be divided equally between two cells—-> highly probable that meiosis produces ___________ _______
aneuploid cells
natural ways causing variations in chromosome number:
_______-____________:chromosomes do not segregate properly.
Meiotic:gametes (too many or too few chromosomes)
Mitotic: somatic cells
______________: interspecies crosses;organisms with sets of chromosomes of two or more species
non-disjunction
alloploidy
meiotic non-disjunction can occur during __________ or __________
meiosis I or meiosis II
___________ ____-__________; all chromosomes migrate to one of the daughter cells
complete non-disjunction
fertilization with a normal gamete can produce a __________ organism.
polyploid
abnormalities in chromosome number after fertilization happens during _______—-> mosaicism(organisms with subset of cells genetically different from the rest)
mitosis
effects depend on timing and location of the first abnormal event in __________ ____-_________
mitotic non-disjunction
mitotic non-disjunction:
bilateral gynandromorph- organisms with one half _______ and one half _________
female, male
____________ are rare and most are sterile
gynandromorphs
___________: more than two sets of chromosomes derived from the same species.
–is less common than ________ (interspecies crosses)
autopolyploid
alloploidy
allopolyploidy: hybridizing 2 or more species and then ___________ doubling
chromosome
interests in production of ___________ and ___________ to generate hybrids with desirable traits for breeding.
alloploidy and allopolyploids
__________ ____________: evolutionary related chromosomes from two different species.
homeologous chromosomes
_______ of alloploids highly related to chromosome pairing
fertility
colchicin binds to tubulin and affects ___________ during meiosis or mitosis: can produce aneuploidy or polyploidy
segregation
individual cells are mixed together and then fused
cell fusion
