Christoffersen MCDB Lecture #6
Sex-linked Traits
Genes carried on sex chromosomes have a special inheritance pattern
Examples:
o White locus in Drosophila (X)
o Re-green color blindness in humans (X)
o TDF gene in humans (Y)
In humans male gametes decide sex uses XY
In chickens the female egg determines the sex and uses ZW
Start of Chapter 15:
Restriction Endonucleases: Where do they come from?
Bacterial cells use restriction enzymes as a way to protect themselves from
foreign DNA.
Restriction enzymes cleave DNA at specific which sequences make them
nonfunctional.
Bacterial cells protect their own DNA from digestion by methylation the DNA at
the sequence recognized by their own restriction enzyme.
How is this all analyzed?
o Restriction enzymes have been isolated from a wide variety of bacteria.
Each enzyme has a unique recognition site.
o By selecting enzymes which cut at site which includes a DNA mutation
allow scientists to detect the presence of a DNA polymorphism.
o An example of this is gel electrophoresis, but only works in a small
genome.