4.4 Abnormal Meiosis Flashcards
Non-disjunction
Non-disjunction is the failure of homologous chromosomes to separate during meiosis
As a result, one daughter cell is missing a chromosome (monosomy while another daughter cell has an extra chromosome (trisomy)
Turner syndrome
one X and no Y ( monosomy) – individuals are female in appearance but do not mature sexually and are sterile
Klinefelter syndrome
2 X and one Y ( trisomy) – individuals are sterile males that exhibit some feminine body characteristics
Patau syndrome
individuals have serious developmental problems, including brain, kidney and heart defects, usually live only for a few months (trisonomy 13)
Edwards syndrome
individuals have many organ system defects, low survival rate, most fetuses die before birth, infants usually live less than 1 month (trisonomy 18)
Prenatal Testing - CVS –chorionic villus sampling
cells removed from outer membrane surrounding embryo
Prenatal Testing - Amniocentesis
fluid from amniotic sac is extracted with a large syringe to prepare a karyotype
Prenatal testing - blood test
At certain points in pregnancy, blood tests from the mother can be used to determine hormone levels, and look for markers of disorders such as spina bifida or Down Syndrome
Artificial insemination (assisted reproductive technologies)
sperm collected, concentrated and then introduced into the female’s reproductive tract
In-vitro fertilization (assisted reproductive technologies)
Egg is fertilized “under glass”, then the embryo is transferred to the uterus of the mother
Non-human uses of assisted reproductive technologies
Saving Endangered species
Breeding of livestock, horses, and pets
Cytoplasmic Inheritance
In sexual reproduction, humans receive the mitochondria from their mother exclusively.
“Mitochondrial Eve” is the woman (or group of women) whom humans share as a recent matrilineal common ancestor
Genetic Variation
Although mitochondria and chloroplast are normally exclusively inherited from the mother, sometimes all the mitochondria and chloroplasts are not genetically identical
Mitochondrial diseases include:
Egg swapping can be used to avoid mt diseases
Myoclonic epilepsy
Epilepsy characterized by short, sharp jerks in muscular tissue
Leigh Syndrome
Children with Leigh syndrome (Leigh’s disease) inherit a gene or mitochondrial change that causes nervous system cells to die. This rare mitochondrial disease causes seizures, developmental delays, heart issues and breathing difficulties. It sometimes affects adults. Treatments can ease symptoms, but there isn’t a cure for this fatal condition.
Leber Hereditary Optic Neuropathy (LHON)
Leber hereditary optic neuropathy is a rare genetic disease that can cause you to quickly and unexpectedly lose your vision. Vision loss for most people occurs sometime in their teens or twenties, over the course of six months to a year. By the end, most are legally blind. There’s no cure yet for LHON, but researchers are working on developing several treatments.
Kearns-Sayre Syndrome
Kearns-Sayre syndrome (KSS) is a rare neuromuscular condition that impacts your eyes and other parts of your body, including your heart. It happens due to a defect in the DNA of mitochondria, which help produce most of your body’s energy. Most people with KSS develop symptoms before age 20. There isn’t a cure, but treatment options can help.
Cytoplasmic Inheritance in Plants
Some of the chloroplasts in plants can be faulty, and not make the chlorophyll that turns them green
This leaves white patches in the leaves, whis is called variegation.
