Transcript PEDIGREE CHARTS

Different Patterns of Inheritance
Blood Types, Sex-Linked and
Polygenic
Traits
Blood Typing!
Phenotype
Genotype
A
AA or AO
B
BB or BO
AB
AB
O
OO
Blood Types

A person who
has:
A-, O- blood
A+ blood
A-, A+, O-, O+ blood
B- blood
B-, O- blood
B+ blood
B-, B+, O-, O+ blood
AB- blood
AB-, O- blood
AB+ blood

Can receive:
A- blood
AB-, AB+, A-, A+, B-, B+, O-, O+
blood
O- blood
O- blood
O+ blood
O-, O+ blood
Type O-negative blood does
not have any antigens.

It is called the "universal
donor" type because it is
compatible with any blood
type.
Type AB-positive blood is
called the "universal
recipient" type because a
person who has it can
receive blood of any type.
+ = have Rh protein
- = no Rh protein
Blood Type Crosses!
Samara is type AB
Naveen is type A
his mother was A, Father O
What are their genotypes?
S= AB
Phenotyp
e
Genotype
A
AA or AO
B
BB or BO
AB
AB
O
OO
N = AO
What are their possible offspring’s
blood types?
50% A
25% AB
25% B
Blood Typing!
Kristina is type B
Kyle is type A
Is is possible for their
child to be type O?
Phenotyp
e
Genotype
A
AA or AO
B
BB or BO
AB
AB
O
OO
Polygenics
 Multiple
 Skin
GENES affect the traits being expressed
color
 Hair color
 Eye color
How it works…
Eye
Eye Color
Color == Brown
Hazel
Skin
SkinColor
Color==Light
Tan
Eye Color
Sex Linked Traits

Sex Chromosomes (X, Y)

In humans male determined sex of offspring
• Give X = female
• Give y= male

Genes can be located on sex chromosomes
= Sex Linked Traits

Mostly on X for humans
Fly Experiment

Eye color carried on X
R = red r = white

More males are white than female because..

SEX LINKED TRAIT!!
(only on X Chromosome)
XY Female XX
100%
50%
0%
50%
Male
Sex Linked Disease
Females can be carriers, males will show it
 Red- green color blindness
 Night Blindness
 Fragile X syndrome
 Sickle Cell Anemia
 Huntington's disease
 Cystic Fibrosis
 Hemophilia
Sex-Linked Genetic Cross
Reinforcement
Pg 175- 176 ( 3 P.R.)
 Pg 180-182 (3 P.R.)

PEDIGREE
CHARTS
A family history of
a genetic condition
What is a pedigree chart?
Pedigree charts show a record of the family of an
individual
 They can be used to study the transmission of a
hereditary condition
 They are particularly useful when there are large
families and a good family record over several
generations.

Studying Human
Genetics

Pedigree charts offer an ethical way of studying human
genetics

Today genetic engineering has new tools to offer
doctors studying genetic diseases

A genetic counsellor will still use pedigree charts to
help determine the distribution of a disease in an
affected family
Symbols used in pedigree charts





Normal male
Affected male
Normal female
Affected female
Marriage
A marriage with five children, two
daughters and three sons. The second
born son is affected by the condition.
Eldest child  Youngest child
Organising the pedigree
chart

A pedigree chart of a family showing 20
individuals
Organising the pedigree
chart

Generations are identified by Roman
numerals
I
II
III
IV
Organising the pedigree chart


Individuals in each generation are identified by Roman
numerals numbered from the left
Therefore the affected individuals are II3, IV2 and IV3
I
II
III
IV
Different Patterns of Inheritance
 Sex-Linked
 Passed
Recessive
on the X or Y chromosome
• Usually X
 What
this means…
• Girls can be carriers (XX)
• Males either have it or are normal (XY)
• Examples:
• Hemophilia, color-blindness, muscular dystrophy
Sex-Linked Recessive

males get their X from their mother

fathers pass their X to daughters only

females express it only if they get a
copy from both parents.

expressed in males if present

Possible Carriers in females
Shown by half filled circles



Usually more males show this!!
Cannot have sick male, normal
mother
Autosomal Dominant
All unaffected
individuals are
homozygous for the
normal recessive
allele.
Autosomal Recessive

All affected are homozygous.

Incest matings are often (but
not always) involved.

Heterozygous are “normal”
Dominant vs. Recessive Autosomal
Is it a dominant pedigree or a recessive pedigree?

1. If two affected people have an unaffected child, it must be a dominant
pedigree


2. If two unaffected people have an affected child, it is a
recessive pedigree:


D is the dominant mutant allele and d is the recessive wild type allele. Both
parents are Dd and the normal child is dd.
R is the dominant wild type allele and r is the recessive mutant
allele. Both parents are Rr and the affected child is rr.
3. If every affected person has an affected parent it is a
dominant pedigree.
Dominant Autosomal Pedigree
1. If two affected people have
an unaffected child, it must be
a dominant pedigree
I
2
1
II
1
2
3
4
5
6
III
1
2
3
4
5
6
7
8
9
10
Recessive Autosomal Pedigree
If two unaffected
people have an
affected child, it
is a recessive
pedigree
Recessive Sex Linked Pedigree
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