Chapter 4.2: Sex Chromosomes and Sex Determination Flashcards
What does the sex chromosome genotype XXX produce in drosophilia?
dies
When is amniocentesis performed?
Performed approximately 16 weeks after woman’s last menstrual period
What does the sex chromosome genotype OY produce in drosophilia?
dies
What does the sex chromosome genotype XO produce in drosophilia?
sterile male
Define sex chromosomes
two distinct chromosomes that provide the basis of sex determination
What does the sex chromosome genotype XX produce in humans?
normal female
Define SRY
sex determining region of Y
What does the sex chromosome genotype XY produce in humans?
normal male
What does the sex chromosome genotype XYY produce in humans?
normal or nearly normal male
What are two distinct chromosomes that provide the basis of sex determination?
sex chromosomes
What does the sex chromosome genotype XXY produce in humans?
Klinefelter male (sterile); tall, thin
Where did evidence of SRY come from?
o Evidence implicating SRY came from sex-reversal: the existence of XX males and XY females
What does the sex chromosome genotype XY produce in drosophilia?
normal male
What are pseudoautosomal regions (PARs)?
o The two ends of the Y chromosome are called pseudoautosomal regions (PARs), because homologous regions are present at the ends of the X chromosome
What is amniocentesis?
o Method to obtain fetal cells whose DNA and chromosomes can be analyzed for genotype
What is a o Method to obtain fetal cells whose DNA and chromosomes can be analyzed for genotype?
amniocentesis
What does the sex chromosome genotype OY produce in humans?
dies
What is the heterogametic sex?
o The sex having two different sex chromosomes is termed the heterogametic sex because it gives rise to two different types of gametes
These gametes in humans would contain either X or Y
What does the sex chromosome genotype XXX produce in humans?
nearly normal male
What does the sex chromosome genotype XX produce in drosophilia?
normal female
Describe amniocentesis
o Doctor inserts needle through pregnant woman’s abdominal wall into the amniotic sac where fetus is growing
o Use ultrasound imaging to guide needle and withdraw some amniotic fluid
Fluid contains living cells called amniocytes shed by the fetus
When placed in a culture medium, these fetal cells undergo mitosis several times and increase in number
o Once enough fetal cells are available, clinicians look at the chromosomes and genes in those cells
What does the sex chromosome genotype XYY produce in drosophilia?
normal male
What does the sex chromosome genotype XXY produce in drosophilia?
normal female
What does the sex chromosome genotype XO produce in humans?
Turner female (sterile); webbed neck
