Transcript Chapter 13.4

Chapter 13.4
Using DNA to Duplicate Existing Mammals
AP Biology
Fall 2010
Embryo Cloning
 Geneticists have been cloning large animals by artificial
twinning for some time
 The embryos are produced by in vitro fertilization, allowed
to develop to the eight cell stage and then separated
 Small clusters of cells are implanted into surrogate mothers,
where they grow into identical clones
Embryo Cloning
Adult Cloning
 The nucleus from an adult animal’s differentiated cell (say
liver) replaces an unfertilized egg’s nucleus by microinjection
in a process known as nuclear transfer
 The cell is induced to divide and chemicals or electric shock
 Soon a cluster of embryonic cells is implanted into a
surrogate mother
Therapeutic Cloning
 Using nuclear transfers , DNA of a somatic cell from the
heart, liver, muscles, or nerves is transplanted into a stem
cell, which is an undifferentiated cell that can still divide
 The descendent cells go on to differentiate into cell types of
specific tissue and organs
 The process is called somatic cell nuclear transfer (SCNT); it
produces stem cells that are a genetic match to a patient
affected by an incurable disease or spinal cord injury
 Also has the potential to regenerate organs