Transcript File - Miss Schwippert

Human Heredity
How can you study human
heredity?
Studying human heredity
Population sampling
determines how often a
trait appears in a small,
randomly selected
group.
This percentage is then
applied to the entire
population to predict the
number of individuals
with that trait.
Studying human heredity
Pedigrees graphically
record inheritance of a
single trait over several
generations.
Typically, the occurrence of
the trait is determined based
on family/historical
documents, interviews,
photographs, & medical
records
Pedigrees
Specific shapes are used to represent
individuals in a pedigree
Individual
Female
Male
With Trait
Without Trait
Pedigrees
Connecting lines are used to indicate
relationships among individuals within the
family
P1
parental
F1
first filial
F2
Second filial
Fill It In …
Draw a pedigree that shows a mom and
dad that have two girls, one boy. The
boy is married. Indicate that all the
males have the trait.
Pedigrees
Pedigrees
demonstrate the
pattern of
inheritance
(dominant/recessive
, sex-linked) of the
single trait.
Pedigrees
Pedigrees can be
interpreted to
determine the
presence of carriers
(individuals who do
not express the trait
but may pass the
gene on to offspring)
Pedigrees
Example: The two
parents (P1
generation) must
have been carriers
(Bb) for a recessive
trait. Neither
showed the trait, but
they had a child with
the trait (bb).
Fill It In …
Signs a pedigree shows a trait that is …
Recessive Sex-linked -
Interpreting a Pedigree
What can you tell from a pedigree?
Whether a family has an autosomal or sexlinked disease or disorder
Autosomal disorder: appears in both sexes
equally
Sex-linked disorder: allele is located only on the
X or Y chromosome. Most sex-linked genes are
on the X chromosome and are recessive
So who would have an X-linked disorder more often,
boys or girls?
Whether a disorder is dominant or recessive
Is this disorder 1) autosomal or sex
linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Brother
You
Sex Linked! (in this case
allele is recessive and
located on the X
chromosome)
Is this disorder 1) autosomal or sex
linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Autosomal dominant!
Brother
You
Practice Pedigree
Type O blood is recessive to Type A and B
blood. Tom had type B blood and married
Shana, who had type A blood. Together, they
had 2 children: Cherith (type O) and Bryan
(type AB). Bryan married Ali (type O) and
they had two children: Christian (type A) and
Jon (who could not donate blood to
Christian). Ali had an affair with Trent, who
was homozygous for blood type A. Ali and
Trent had a child with type A blood.
Common Genetic Disorders
Color blindness
Sickle cell anemia
Cystic Fibrosis
Hemophilia
Huntington’s Disease
For more info, go to: http://www.ncbi.nlm.nih.gov/pubmedhealth/
Color Blindness
 Deficiency to
percieve colors
 Problem with color-
sensing pigments in
certain nerve cells
of the eye
 About 1 in 10 men
have some form of
color blindness.
 Sex-linked disorder
Sickle Cell Anemia
 Disorder where
abnormal hemoglobin (a
protein inside red blood
cells) is produced and
warps red blood cells
 Sickle cells deliver less
oxygen to body’s tissues
and can get stuck in small
blood vessels
 Recessive trait, tends to
be seen in people of
African or Mediterranean
descent
Cystic Fibrosis
 Recessive, autosomal disease
 Life threatening, causes thick mucus to
build up in various areas of the body
(lungs, digestive tract, etc).
 Tends to run in Caucasians, of
Northern/Central European descent
(1 in 29 Americans
carry the allele)
 Average life span in US
for people with CF is 37,
death usually caused by
lung complications
Hemophilia
 Bleeding disorder, where it takes a long time
for blood to clot (body lacks proteins
involved in clotting)
 Sex-linked
(carried on the X
chromosome)
 Treatment
involves
injection with
missing clotting
protein
•Describe the trait or disease you chose
Huntington’s Disease
 Autosomal, dominant
 Deterioration of brain
tissue, usually begins
between age 30 and
40.
 No cure, but have
medications to cope
with symptoms
 People usually die 1520 years after onset of
degeneration
•Describe the trait or disease you chose
Some History
Hemophilia has played
an important role in
Europe's history
The disease began to
crop up in Great Britain's
Queen Victoria’s children
It became known as the
"Royal disease" because
it spread to the royal
families of Europe
through Victoria's
descendants
How it Spread
it spread through the
Royal Houses of
Europe as monarchs
arranged marriages to
consolidate political
alliances.
We can trace the
appearance of
hemophilia as it popped
up in Spain, Russia,
and Prussia by looking
at the family tree.
The Royal Family Tree
Queen Victoria's son Leopold's
Family
His daughter, Alice of
Athlone, had one
hemophilic son (Rupert)
and two other children - a boy and a girl -whose status is
unknown.
What is the chance that
her other son was
hemophilic?
What is the probability
that her daughter was a
carrier? hemophiliac?
German and Russian
Influences
Check Yourself!
1. In a pedigree, what shape represents a male?
2. What are lines used to indicate in a pedigree?
3. What do pedigrees tell us about the
inheritance of a trait in a family?
Check Yourself!
1. In a pedigree, what shape represents a male?
SQUARE
2. What are lines used to indicate in a pedigree?
3. What do pedigrees tell us about the
inheritance of a trait in a family?
Check Yourself!
1. In a pedigree, what shape represents a male?
SQUARE
2. What are lines used to indicate in a pedigree?
RELATIONSHIPS AMONG INDIVIDUALS
3. What do pedigrees tell us about the
inheritance of a trait in a family?
Check Yourself!
1. In a pedigree, what shape represents a male?
SQUARE
2. What are lines used to indicate in a pedigree?
RELATIONSHIPS AMONG INDIVIDUALS
3. What do pedigrees tell us about the
inheritance of a trait in a family? PATTERNS
OF INHERITANCE (DOMINANT/RECESSIVE
OR SEX-LINKED)
PRESENCE OF CARRIERS