25 Questions
Which term refers to genes that affect multiple, apparently unrelated phenotypes?
Pleiotropy
What does the term 'pleiotropy' mean?
One gene affecting multiple traits
In which disorder is a mutation in a pleiotropic gene discussed in the text?
Phenylketonuria (PKU)
What does the word 'pleiotropy' signify etymologically?
'Affecting many'
Pleiotropy is NOT to be confused with:
Polygenic traits
What initiates the development of a testis in an XY embryo around the seventh week?
Absence of the Y chromosome
Which factor is responsible for causing undifferentiated gonadal tissue to form testes?
Testis determining factor
During male gametogenesis, what is critical for segregation of the X and Y chromosomes?
Synapsis and recombination in PARs
What continues to be expressed even from the Barr body in females?
Pseudoautosomal regions
What differentiates into structures of the female reproductive tract?
Müllerian ducts
What is the purpose of the Chi-Square (𝛘2) Goodness-of-Fit Test mentioned in the text?
To determine the likelihood of chance causing deviation between observed and expected ratios
How are degrees of freedom (d.o.f) calculated in the context of the Chi-Square (𝛘2) Goodness-of-Fit Test?
By subtracting 1 from the number of categories
What does the critical value, P(0.05) at d.o.f = 1 being 3.841 indicate in Table 3.7?
The threshold for determining whether deviation is due to chance
In the context of genetic crosses, what does the null hypothesis state?
There is no significant difference between the observed and expected ratios
What does the Forked line/Branch Diagram represent in relation to dihybrid and trihybrid crosses?
Application of Probability rules in genetic crosses
What is the term used to describe the presence or absence of extra digits, which can exhibit incomplete penetrance and variable expressivity?
Phenotype variability
Which factor may contribute to incomplete penetrance and variable expressivity in genetic traits such as polydactyly?
Sex hormones
In gene interactions, what is the term used to describe the masking effect of one gene over another at a different locus?
Epistasis
Which gene interaction pattern results in a 9:3:4 phenotypic ratio in dihybrid crosses?
Duplicate recessive epistasis
What gene interaction type produces a 15:1 phenotypic ratio in dihybrid crosses?
Dominant and recessive epistasis
What did Lyon hypothesize about the inactivation of X chromosomes?
It occurs randomly in somatic cells at a specific stage in embryonic development.
Why do X-linked coat color patterns not occur in male cats?
Because male cats have only one maternal X chromosome and are hemizygous for X-linked coat-color alleles.
Which gene is known to be critical for X-inactivation?
X-inactive specific transcript (Xist)
Where is the X-inactivation center (Xic) located on the mammalian X chromosome?
In the p arm
What type of pattern was observed in the coat colors of female tortoiseshell and calico cats?
Spotted pattern
Learn how to create forked line diagrams for Dihybrid and Trihybrid crosses while applying probability rules. Practice solving problems to calculate the probability of obtaining specific offspring phenotypes. Test your understanding with a challenge on phenotype ratio calculations.
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