Ch.11 – Complex Inheritance & Human Heredity 11.2 – Complex Patterns of Inheritance Sometimes...

Ch.11 – Complex Inheritance & Human Heredity 11.2 – Complex Patterns of Inheritance

Sometimes inheritance does not follow Mendel’s rules(Non-Mendelian Genetics)

X = X =

X = X =

Skin Tone Eye Color


Incomplete Dominance

The heterozygous phenotype is a blend of the dominant and recessive

Rr

Rr

R r

R

r

R R

r

r

RrRr

RrRr

RR

rr


Codominance

Both alleles are expressed

Rr

Rr

R r

R

r

R R

r

r

RrRr

RrRr

RR

rr

RR

rr

Rr RrRr

Rr

RrRr

RRrr


Codominance


Population affected with Sickle Cell

Anemia

Population with a high risk of

contracting Malaria

Malaria Animation

http://www.montereyinstitute.org/courses/AP%20Environmental%20Science/course%20files/multimedia/lesson85/animations/5c_malaria.html


Multiple Alleles

There are more than 2 alleles for a particular trait

For blood type in humans there are 3 alleles

ABO

(ABO blood type)A & B are Co-Dominant &

O is Recessive


Type AType A

Type BType B

Type ABType AB

Type OType O

AA

BB

A & BA & B

nonenone

BB

AA

nonenone

A & BA & B

A & ABA & AB

B & OB & O

ABAB

AllAll OO

AllAll

B & ABB & AB

A & OA & O

Blood Types Antigen Antibody

Can Give to:

Can Receive From:


IA i

IB

i

IA IB IB i

IA i i i

Type AType A

Type BType B

Type ABType AB

Type OType O

IA IBIA IB

IA IA or IA i IA IA or IA i

IB IB or IB i IB IB or IB i

i ii i

Phenotype Genotype

What are the possible blood types for the children of a heterozygous type A

woman and a heterozygous type B

man?


Polygenic Traits

more than one pair of genes code for a particular trait----------------------

The occurrence of the phenotypes of a polygenic trait usually form a bell curve


Sex determination in humans


Sex determination in humans

X Y

X

X

XX

XX

XY

XY

XX x XY


Sex-Linked Traits

Traits found on the sex chromosomes More traits are found on the X-chromosome than the Y


Sex-Linked Traits

Red-green colorblindness and hemophilia are x-linked, recessive disorders


Sex-Linked Traits

Females are far less likely to have an x-linked recessive disorder.

XB Y

XB

Xb

XBXB

XBXb

XBY

XbY

A cross between a carrier female and a male with

normal vision will lead to the following:

Ch.11 – Complex Inheritance & Human Heredity 11.1 – Human Heredity

Genetic Disorders

Autosomal Recessive Disorders.

Cystic Fibrosis

Albinism

Tay-Sachs

Defective membrane protein leads to digestive & Respiratory

failures

Little to no melanin production which causes skin and eye

damage from UV rays

Inability to break down fatty substances leads to a buildup in the brain and mental disabilities


Genetic Disorders

Autosomal Dominant Disorders.

Huntingtons

Achondroplasia

Decline of mental and neurological function

Dwarfism


Pedigree Analysis

(Inter-family)

(The subject being studied)


Which shows a dominant and which a recessive autosomal disorder?

Recessive

Dominant (or recessive)


Sex-Linked Recessive


What are the genotypes for I-1 & I-2?II-1 & II-2?

III-1, III-2 & III-3?

Aa Aa

A? aa

Aa Aa Aa

A? A? A?


When carriers are shown on a pedigree you know all genotypes (sometimes carriers are

shown sometimes they are not)

XAXa XAY

XaYXAXA

Ch.11 – Complex Inheritance & Human Heredity 11.3 – Chromosomes & Human Heredity

Kleinfelter’s Syndrome

Down Syndrome

Chromosomal Disorders


Nondisjunction


Trisomy will usually cause death very early in pregnancy.

Trisomy 13,15,18, & 22 have been documented (most die before age 1)

Trisomy 21

Down Syndrome

abnormal facial appearance, high likelihood of mental

retardation (degree varies considerably), and increased

likelihood of developing leukemia and Alzheimer’s

disease

Klinefelter’s SyndromeUnderdeveloped

reproductive organs & infertility.

May also cause Enlarged breasts & a

decrease in mental function.


Nondisjunction in Sex Chromosomes

Turner’s SyndromeUnderdeveloped

reproductive organs & infertility.

Short stature and decreased mental function

Ch.11 – Complex Inheritance & Human Heredity 11.2 – Complex Patterns of Inheritance Sometimes...

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