Karyotypes & Pedigrees Flashcards
What is a pedigree?
chart showing relationships within a family to analyze the pattern of inheritance.
What 2 things can a pedigree show?
- shows the presence or absence of a trait according to the relationships
- can determine if an allele for a trait is dominant or recessive, autosomal or sex linked
What is a carrier?
person that inherits the recessive alleles but does not express the trait
Whats a karyotype?
display showing the diploid (2n) set of chromosomes grouped together in pairs arranged in order of decreasing size
How many chromosomes are in a human karyotype?
46 ( 2 pairs of 23 )
What are autosomes?
first 44 chromosomes
What are sex chromosomes?
determine an individual gender : last 2 chromosomes of the 46
What’s the chance of having male or female?
50/50
What chromosome do all eggs carry?
X chromosome
How does the male sperm determine the sex of the offspring?
Half of the sperm carry an X chromosome; other half carry the Y chromosome
How many genes are found on the X chromosome?
1200 genes
How many genes are on the Y chromosome?
140 genes ( for sex determination & sperm development
Is X or Y smaller?
Y is smaller
What does the circle symbol mean?
a female
What does the square symbol mean?
a male
What does the shaded symbol mean?
a trait is present
What does the unshaded symbol mean?
a trait is NOT present
What does the row of symbols mean?
the # of generations
What does the horizontal line symbol mean?
a relationship
What does the vertical line symbol mean?
connects offspring
How are the individuals represented?
the normal #’s (left to right; oldest to youngest)
What’s Down syndrome ?
Trisomy on chromosome 21
What are the effects with down syndrome ?
mental retardation; short stocky body, neck, fingers, toes & enlarged tongue
What is Turners syndrome?
Missing one X chromosome in females
