Inheritance Patterns

Eukaryotic Cell Nucleus

Gamete Formation Meiosis Animation Haploid # 2 Diploid # 4

Crossing Over Meiosis Animation http://www4.ncsu.edu/unity/users/b/bnchorle/www

Conception Sammy sperm entering Emily egg...

A few hours after conception L E A V G

Mitosis Review Mitosis Animation Anaphase Prophase Metaphase Telophase

prophase G1 S G2 metaphase telophase anaphase Mitosis Animation Daughter cells Mitosis Animation

Karyotypes A profile of a person's chromosomes Arranged and numbered by size, from largest to smallest Used to identify chromosomal aberrations that may result in a genetic disorder Abnormal positions of chromosomes, extra pieces or missing pieces usually cause problems with a person's growth, development, and body functions Prepare a standard karyotype using Metaphase cells from most populations of dividing cells http://learn.genetics.utah.edu/units/disorders/karyotype/karyotype.cfm

Chromosomal deletions Chromosomal insertions Chromosomal duplications Nondisjunction Chromosomal deletions Chromosomal insertions Chromosomal duplications

Caused by Nondisjunction Polyploidy Most common is Trisomy Caused by Nondisjunction 35% Trisomy conceptions < 1% 15 30 45 Mother’s Age Years

Down Syndrome Karyotype Trisomy 21

Cleft Palate Trisomy 13 Patau Syndrome 1 in 15,000 live births Condition is Lethal

Klinefelter Male XXY occurs 1 in 1000 births

Kleinfelter’s Syndrome Trisomy Animation People with this disorder develop as males with subtle characteristics that become apparent during puberty. They are often tall and usually do not develop secondary sex characteristics such as facial hair, or underarm and pubic hair.

Autosomal Dominant Recessive

d d d d d d d d d d d

Examples of Autosomal Dominant Inheritance Achondroplasia = dwarfism associated with defects in growth regions of long bones Familial Polycystic Kidney Disease = formation of cysts in kidneys; leads to hypertension kidney failure Familial Hypercholesterolemia =Elevated levels of cholesterol; predisposes to plaque formation, cardiac disease,maybe the most prevalent genetic disease Huntington Disease =Progressive degeneration of the nervous system,Dementia, early death Marfan Syndrome = Connective tissue defect; death by aortic rupture

Achondroplasia Autosomal Dominant Autosomal Recessive

Usually inherited as an autosomal dominant Polydactyly demonstrates how gene expression can vary. As the human embryo develops, a dominant allele “D” controls how many sets of bones will form in the hands and feet. The “Dd” genotype varies in how it is expressed.

Autosomal Dominant Disorder Huntington’s Disease Autosomal Dominant Disorder Brain Deterioration

Flo Hyman died from Marfan Syndrome Autosomal Dominant AFFECTS Skeletal System Cardiovascular System Eyes...

Abraham Lincoln Marfan Syndrome?

n n n n n n n n

Examples of Autosomal Recessive Inheritance Albinism = absence of pigment in skin, eyes, hair Cystic Fibrosis = mucous production that blocks ducts of certain Glands, lung passages, often fatal by early adulthood Galactosemia = accumulation of galactose in liver; mental retardation Phenylketonuria = excess accumulation of phenylalanine in blood, Mental retardation Sickle Cell Anemia = abnormal hemoglobin, blood vessel blockage, Early death Xeroderma Pigmentosum = lack of DNA repair enzymes, sensitivity to UV light, skin cancer, early death Tay-Sachs Disease = improper metabolism of gangliosides in Nerve cells; early death

Albinism No Pigmentation No Expression of the Melatonin Genes is an Autosomal Recessive Condition No Expression of the Melatonin Genes No Pigmentation

Sex-Linked

Hairy Ears is a Y-linked Trait. One allele produces non-hairy ears the other allele produces rather long hairs.

Sex Chromosome Inheritance Pattern X-linked Recessive Most common Sex Chromosome Inheritance Pattern X-linked Recessive Hemophilia = defects in blood clotting mechanisms Adrenoleukodystrophy = atrophy of adrenal glands, Mental deterioration, death 1 to 5 years after onset Colorblindness = some forms Muscular Dystrophy = Duchene type; progressive fatal condition; accompanied by muscle wasting

How X-linked inheritance works One Possible Scenario The female sex chromosomes of an unaffected mother (who carries an auditory condition) have one faulty gene and one normal gene. The father has the normal gene on the X chromosome, and a normal Y chromosome.

R r Hears Hears R R R R R R R

Affected Male

Color Blindness: Sex Linked What number do you see? #8 She Blinded me… X linked

The individual with normal color vision will see a 5 revealed in the dot pattern. An individual with Red/Green (the most common) color blindness will see a 2 revealed in the dots. http://www.toledo-bend.com/colorblind/Ishihara.html

Multiple Alleles

Rh factor + or -- In addition to the blood group (A, B, O, AB), the Rh factor is either positive (present) or negative (absent). Rh positive is autosomal dominant! This factor does not effect your health except during pregnancy.

A woman who is negative Rh factor Married to a man who is positive Rh factor This combination can produce a child who is Rh positive. Mother's and baby's blood systems are separate If the blood from the baby mixes with mother's blood, it can cause the mother to create antibodies against the Rh factor. The Rh positive baby becomes an intruder in his/her mother’s uterus

Both alleles are expressed as Dominant in the heterozygote Co-dominance Both alleles are expressed as Dominant in the heterozygote Intermediate/Incomplete Dominance Alleles blend in the heterozygote