Sex Determination & Sex Chromosomes Flashcards
Sex determination
Underlying mechanism by which individual develops into a female or male
_____________ may depend on the presence of sex chromosomes
Sex differences
___________ determines gender in many species
Sex chromosome (X-Y system)
In mammals a male carries ___________ chromosome & a female has ___________ chromosme
One X & one Y chromosome, female carries two X chromosomes
Males are ____________ since they carrry one X & Y chromosome
Heterogametic sex
Females are ___________ since they have 2 X chromosomes
Homogametic sex
Autosomes
Chromosomes that are not sex chromosomes
The presence of ______________ is what determines if a gender is male or female
Y chromosome (male has Y chromosome & feamle dont)
The _________ system is used in mammals
X-Y system
The ________ system is used in insects
X-O system
The _________ system is used for birds & fish
Z-W system (ZZ-male & ZW - female)
The ___________ system is used in bees, wasps, & ants
Haplodiploid system
Dosage Compensation
Refers to the phenomenon in which the level of expression of many genes on the sex chromosomes is similar in both sexes even though males & females have a different complement of sex chromosomes
Dosage compensation is necessary in some species to ensure ____________ between the sexes
Gentic equality
Dosage compensation occurs in female mammals by the _____________ of one X chromosome
Inactiviation
X-chromsomes inactivation in mammals depends on the __________ & ___________
X-inactivation center & the Xist gene
The _______ plays a main role on X-chromosome inactivation where it must be found on the x-chromosome for inactivation to occur
Xic
The ______ forms proteins that coats the x-chromosomes & inactiviates it
Xist
What are the 3 phases of X-chromosome inactivation?
- Initation
- Spreading
- Maintence
Sex-linked genes
Genes that are found on only one sex chromosome but not both
X-linked genes
Found only on the X chromosome
Y-linked genes
Found only on the Y chromsomes
Pseudoautosomal genes
Found on both the X & Y chromosomes
X- linked alleles
X-linked genes
The __________ can be used to protect the probability of independent outcomes
Product rule
Product Rule
The probability that two or more independent outcomes will occur is equal to the product of their individual probabilities
The ______________ can be used to predict the probability of an unordered combination of outcomes
Binomial Expanison equation
The __________ test is used to test the validity of a genetic hypothesis
Chi square
Binomial expanison equation
P= n!/ x!(n-x)! pxqn-x
The ___________ is used to determine
The ___________ is used to determine if a genetic hypothesis is consistent with the observed outcome of a genetic cross
Chi square test
A ______ chi square value means a high probability that the observed deviation is due to random chance
Low
