Chromosomes: Gametes and preimplantation human embryos Flashcards
Haploid gametes produce ___________ offspring
DIploid
What are some examples of aneuploidy?
Trisomy and monosomy
Haploidy is _________ set(s) of chromosomes
One
Polyploidy is more than _________ chromosomes
2N
Chromosomes rearrangements include translocations, deletions, ___________ and duplications
Inversions
True or false: The risk of having a child with chromosomal aberrations is smaller when a woman is older vs when a woman is younger
False, it is the opposite way around
True or false: Older men are 3 times more at risk of having children with Trisomy 21 than younger men
True
When can chromosome abnormality occur in gametogenesis?
Meiosis I and II, oogenesis, spermatogenesis
When can chromosome abnormality occur in fertilization?
Dispermic fertilization, digynic fertilization after ISCI, parthogenetic activation
When can chromosome abnormality occur in embryogenesis?
Mitotic error
What is the phenomenon of abnormal chromosome segregation?
Non-disjunction
When does non-disjunction occur during meiosis I in eggs?
Anaphase I
What is the result of non-disjunction during meiosis I in eggs?
Disomic and nullisomic gametes
Normal chromosome segregation in meiosis I results in ___________ gamete
2N
Non-disjunction in meiosis I leads to __________ or ____________
Trisomy; monosomy
Pre-division of chromatids in meiosis I leads to _____________
PSSC (premature separation of sister chromatids)
True or false: Pre-division of both univalents leads to a balanced MII oocyte
True
Which aspects of abnormal chromosome segregation are present in meiosis I but not in meiosis II?
Recombination failure, premature homologue separation
Karyotyping in eggs indicated an incidence rate of aneuploidy equal to ________ %
10-35
Which method for detecting aneuploidy in eggs had the highest incidence?
CGH
PSSC in sperm leads to ________, normal and ____________ spermatozoa
Disomic; nullisomic
True non-disjunction in sperm leads to ___________ and _______________ spermatozoa
Disomic; nullisomic
Which methods are used to observe aneuploidy in sperm?
FISH and karyotyping
What are other methods to observe human aneuploidy?
SKY and NGS
FISH technology uses a probe __________ labelled with fluorescent dye
DNA
Which four methods are used for detection of chromosomal copy number variation?
FISH, CGH, aCGH and SNP
Abnormal fertilized embryo shows _______ pronuclei instead of __________
Three; two
Digynic triploidy is characteristic of _____________ of a second polar body
Suppression
What is a mosaic embryo?
A mix of normal and abnormal cells
Mitotic error occurs in which stage of mosaic embryo formation?
2-cell stage
Mosaicism is the presence of one or more genetically distinct cell lines within an ___________
Embryo
Mosaicism is generated from a post ___________ error in an originally ___________ zygote
Zygotic; diploid
What is trisomy zygote rescue?
Post zygotic error in an originally aneuploid zygote that leads to loss of one chromosome
Uniparental disomy results in an embryo carrying _________ parent’s gamete
One
What percent of FISH results showed mosaic cells?
47%
What are the two types of mosaic cells in blastocyst?
dp (polyploid) and da (aneuploid)
A good quality blastocyst has a ______________ percent of polyploid cells than a bad quality blastocyst
Lower
Which mechanisms are behind gain and loss error?
Non-disjunction, anaphase lag, chromosome demolition, chromosome replication
Abnormal cells are allocated to the ______________
Trophectoderm
Meiotic mosaicism often have adverse effect on the conceptus such as ____________ zygote rescue due to the presence of ___________ in the embryo/fetus
Trisomy; UPD
In the case of trisomy 16, the fetus _______
Dies
What is the most common trisomy after trisomy 16?
Trisomy 21 and 22
Which trisomies are seen in live-born apart from sex chromosome abnormalities?
Trisomy 21, trisomy 13, trisomy 18
Edward syndrome (Trisomy 18) is characterized by a _________ sternum, overlapping fingers with clenched __________ and _____________
Short; fists; clubfoot
Patau syndrome (Trisomy 13) is characterized by defects of the __________, cleft _______ and palate and closely spaced ________
Brain; lip; eyes
What are some sex chromosome abnormalities?
Turner syndrome (XO), Klinefelter syndrome (XXY), triple X, XYY
What are some effects of Turner syndrome?
Short stature, broad chest, poor breast development
Klinefelter syndrome affects one in 660 __________
Men
What is the medical treatment for Klinefelter syndrome?
Testosterone replacement therapy
What are some features of people with Klinefelter syndrome?
Tall stature, increased risk of learning disabilities, delayed development of speech and language skills and normal fertility
What produces 47,XYY?
Parental non-disjunction at meiosis II resulting in an extra Y chromosome in sperm
