Transcript Studying human heredity

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on family/historical
documents, interviews,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 -
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.
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