Download Genes

Generation to Generation
Chromosomes: Tiny structures with in the nuclei
of cells that carry information about heredity traits.
~Cells in the body contain 46 chromosomes: 23
pairs.
~At the foundation of chromosomes is the
chemical compound- DNA.
~Specific information about heredity are carried
w/in sections of chromosomes called Genes.
Genes: Segments of DNA molecules are paired.
~Dominant Genes: genes that generally show up in
the offspring whenever they are present.
~Recessive Genes: Usually show up only when
dominant genes are not present.
(Example: Blue eyes are recessive, Brown eyes are
dominant. If mom has blue eyes, and dad has brown
eyes, most likely the child will have brown eyes.)
Genes & Gender
~A zygote has 46 chromosomes- 23 each parent.
~Males have xy, y is the shorter chromosome.
~Female has xx, both are the same.
~Ova and sperm have only 1 chromosome
~Ova have only x
~Sperm have x or y
*The sex of the child is determined by the type of
sperm that finds the egg (Ova).
Genetic Disorders
Sickle Cell Anemia: Disease occurs when a child inherits the
hemoglobin (Oxygen-carrying part of blood) gene from both parents.
The red blood cells develop a sickle shape and clump together
obstructing blood flow and oxygen to the tissues.
~Symptoms- severe joint and abdominal pain, weakness & kidney
disease.
Tay-Sachs Disease: Causes destruction of nervous system,
blindness, and death during early childhood.
Cystic Fibrosis: Makes breathing and digestion difficult, its caused
by abnormal genes, one from each parent.
Down Syndrome: Caused by a chromosomal abnormality known as
Trisony-21,( the presence of three copies of the 21st chromosome).
As a result, the affected person has an extra 47th chromosome in all
body cells. Risk = 1 in 75 at the age of 40
Identifying Disorders
Ultrasound: Sound waves are used to project light images
on a screen. This determines if fetus is in the correct
position and how many fetus are in uterus.
• Test can determine structural defects such as heart
malformations, cleft lip or palate.
3D
Ultrasound
Amniocentesis: A syringe is inserted through the pregnant
woman’s abdominal wall into the amniotic fluid surrounding the
developing fetus.
~Performed 16-20 weeks after fertilization.
Chorionic Villi Sampling: A small piece of membrane is
removed from the Chorion ( a layer of tissue that develops
into the placenta). Takes place around the 8th week of
fertilization.
• This is done earlier then amniocentesis.
• Only done if Genetic Disorders are suspected or inherited.
• Checks for Genetic Disorders