The Chromosomal Basis of Inheritance Flashcards
What is the chromosome theory of inheritance?
The theory that chromosomes are linear sequences of genes. The unifying theory stating that inheritance patterns may be generally explained by assuming that genes are located in specific sites on chromosomes
Why did Morgan chose the fruit fly as his experimental organism?
Easy to work with; reproduce quickly; autosome and sex chromosome
What did Morgan discover amongst the fruit flies he was examining?
Mutation in eye color- white eyed males
What is wild type?
What is commonly seen in the population
What is mutant phenotype?
Mutant phenotype is uncommon in the population
What is hemizygous and what does it mean genetically?
One allele on the X chromosome no corresponding on the Y (usually)
What is homogametic?
Makes one type of gamete
What is heterogametic?
makes two types of gametes
What is the chromosomal basis of sex in humans?
The X-Y system
What is the chromosomal basis of sex in grasshoppers, cockroaches, and some other insects?
The X-0 system (males don’t have sex chromosome)
What is the chromosomal basis of sex in birds, some fishes and insects?
The Z-W system (female hemizygous with ZW and male homo ZZ)
What is the chromosomal basis of sex in most bees and ants?
The halo-diploid system (female 32 male 16)
What does SRY stand for? What does the SRY gene code for?
Gene on the Y chromosome; stands for Sex determining Region of Y; it codes for the development of testis (codes for the protein that does the development)
What do we mean by “sex linked genes”?
Found on the sex chromosomes
What is so different about the inheritance of Y-linked and X-linked genes?
Everyone gets an x; only half get a y
What is a Barr body and what does its presence mean?
A chromosome is heterochromatic meaning very condensed–> that one will not show phenotypically
When does X inactivation in female mammals occur and what does that mean?
50/50 an which one is inactive and means that the one that is active will be dominant
What is nondisjunction and how does it result in abnormal chromosome numbers?
When the chromosomes in meiosis I or the chromatids in meiosis II are not separating
What is aneuplodiy?
Too many or too few chromosomes
What is a deletion in chromosome structure?
A deletion removes a chromosomal segment; CHANGES ALLELE NUMBER
What is duplication in chromosome structure?
Duplication repeats a segment; CHANGES ALLELE NUMBER
What is inversion?
Reverses a segment within a chromosome; NOCHANGE in number
What is translocation?
Moves a segment from one chromosome to a non homologous chromosome; NO CHANGE in number
What is it called when you have 3 21 chromosomes?
trisomy; down syndrome
What is is called when a male has an extra X
Clinefeller’s syndrome
What is it called when a male has an extra Y
Jacobs syndrome
What is is called when a female has an extra X
Trisomy X
What is it called when a female is missing an X
Monosomy X; Turners Syndrome
What is is called when you have a deletion in chromosome 5
Cri-du-chat syndrome
