Question 1
Question
What is it called when homologous chromosomes fail to separate properly?
Question 2
Question
The following shows the sister chromatids failing to separate during Meiosis 2- aka Precocious sister chromatid separation
Question 3
Question
Of the four gametes, 2 of one pair are normal, and of the other pair one is disomic and the other is nullosomic- what has gone wrong?
Question 4
Question
What is different about Meiosis II non-disjunction and Precocious sister chromatid separation?
Answer
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In MII, the nullosomic and disomic gametes occur from the same cell
In PSCS, the nullosomic and disomic gametes occur from different cells
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In PSCS, the nullosomic and disomic gametes occur from the same cell
In MII, the nullosomic and disomic gametes occur from different cells
Question 5
Question
Aneuploidy- an abnormality of chromosome number where the number of chromosomes present is not a multiple of the haploid number
Question 6
Question
Nullosomy- where one of the chromosomes is lost (2n-1)
Question 7
Question
Monosomy is universally lethal to humans embryo's
Question 8
Question
Which of the following is fatal in animals but not always in plants
Answer
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Nullosomy
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Trisomy
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Monosomy
Question 9
Question
Trisomy's of some chromosomes are survivable in humans
Question 10
Question
Down's Syndrome is caused by trisomy of which chromosomes?
Question 11
Question
Down's Syndrom is present in 1/750 babies
Question 12
Question
Which of the following are potentially symptoms of Down's Syndrome?
Answer
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Abnormal fingerprints
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Congenital heart disease
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Gigantism
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Intellectual disability
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Webbed fingers
Question 13
Question
Trisomy 18 is Ptau's syndrome and is found in 1/6000 births
Question 14
Question
Which of the following are potentially symptoms of Edwards syndrome?
Question 15
Question
Ptau's Syndrome is the most common, present in 1/200 births
Question 16
Question
List the potential symptoms of Ptau's syndrome
Question 17
Question
In fetus' with Ptau's Syndrome, there are 100x more spontaneous abortions/lost pregnancies that stillbirths
Question 18
Question
When distinguishing between types of mis-segregation, what is required for direct assessment of genetic markers (ideally)?
Answer
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Allele- specific PCR.
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Genetic information from siblings
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Genetic offspring from a parent
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Genetic offspring from both parents
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Genetic offspring from grandparents
Question 19
Question
90% of aneuploidy's are caused by the sperm, not the egg
Question 20
Question
Define Pleiotropy
Answer
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Where mutation in a single gene only causes a change in a single trait
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Where mutation in a single gene can cause multiple, seemingly unrelated phenotypes
Question 21
Question
Aneuploidy effects entire chromosomes, and so its effects are always Pleiotropic
Question 22
Question
A phenotype associated with a pleiotrophic gene may show greater expressivity than another phenotype associated with the same gene
Question 23
Question
Match the following Trisomies with the problematic chiasmata in the Maternal Meiosis diagram
Answer
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Top- 16 (proximal)
Mid- 18 (achiasmate)
Bot- 21 (achiasmate, proximal, distal)
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Top- 21 (proximal)
Mid- 18 (achiasmate)
Bot- 16 (achiasmate, proximal, distal)
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Top- 18 (proximal)
Mid- 16 (achiasmate)
Bot- 21 (achiasmate, proximal, distal)
Question 24
Question
Without crossover, only 40% of homologous chromosomes align correctly
Question 25
Question
Define the Chiasma hypothesis
Answer
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Chiasma make the cell more vulnerable to aneuploidy
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Without crossover, cells become more vulnerable to aneuploidy
Question 26
Question
Silkworm females and male sloths pair each side of the synaptonemal complex with no crossing over
Question 27
Question
Once produced, how are oocytes stored in the uterus and for how long?
Question 28
Question
The way oocytes are stored is known as Dictyate Arrest
Question 29
Question
What makes the continued arrestment of oocytes in bivalent form difficult?
Answer
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Cohesin is lost as cells age
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DNA begins to degenerage if held in bivalent form too long
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Bivalents held together too long will bind too tight to be unwound
Question 30
Question
List the three things that can happen in an aging oocyte
Answer
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The bivalent cannot be broken
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The DNA begins to degrade
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There is precocious loss of centromere cohesin in Meiosis I
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There is Precocious Separation of sister chromatids
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A univalent is formed
Question 31
Question
During dictyate arrest, achiasmate segregation factors can deplete