Page 140 - 86 human physiology part-2

Genetics and Inheritance

A http://www.studiodaily.com/main/technique/tprojects/6850.html
B http://multimedia.mcb.harvard.edu/media.html

Select A the video of the Inner Life of a Cell. If you want to hear the descriptions in this process
go to B web site and select the Inner Life: view the animation.

Inheritance

Children inherit traits, disorders, and characteristics from their parents. Children tend to resemble
their parents especially in physical appearance. However they may also have the same mannerisms,
personality, and a lot of the time the same mental abilities or disabilities. Many negatives and positives
tend to "run in the family". A lot of the time people will use the excuse "It runs in the family" for things
that have alternative reasons, such as a whole family may be overweight, yes it may "run in the family"
but it could also be because of all the hamburgers and extra mayo that they all eat. Or the fact that after
they eat the hamburgers they all sit on the couch and don't move for the rest of the evening. Children
may have the same habits (good or bad) as their parents, like biting their nails or enjoying reading
books. These things aren't inherited they are happening because children imitate their parents, they
want to be like mom or dad. Good examples are just as important as good genes.

Inheritance
pattern Description Examples

Only one mutated copy of the gene is needed for a person
to be affected by an autosomal dominant disorder. Each
affected person usually has one affected parent. There is a Huntingtons disease,
50% chance that a child will inherit the mutated gene. Neurofibromatosis 1,
Autosomal Many disease conditions that are autosomal dominant have HBOC syndrome,
dominant
low penetrance, which means that although only one Hereditary nonpolyposis
mutated copy is needed, a relatively small proportion of colorectal cancer
those who inherit that mutation go on to develop the
disease, often later in life.

Two copies of the gene must be mutated for a person to be
affected by an autosomal recessive disorder. An affected Cystic fibrosis, Sickle
person usually has unaffected parents who each carry a cell anemia, Tay-Sachs
Autosomal single copy of the mutated gene (and are referred to as disease, Spinal muscular
recessive
carriers). Two unaffected people who each carry one copy atrophy, Muscular
of the mutated gene have a 25% chance with each dystrophy
pregnancy of having a child affected by the disorder.

X-linked X-linked dominant disorders are caused by mutations in Hypophosphatemia,
dominant genes on the X chromosome. Only a few disorders have Aicardi Syndrome
this inheritance pattern. Females are more frequently
affected than males, and the chance of passing on an X-
linked dominant disorder differs between men and women.
The sons of a man with an X-linked dominant disorder will
not be affected, and his daughters will all inherit the
condition. A woman with an X-linked dominant disorder
has a 50% chance of having an affected daughter or son

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