Eukaryotic CellNucleus

Diploid # 4Haploid # 2

Meiosis Animation

Meiosis Animation

http://www4.ncsu.edu/unity/users/b/bnchorle/www

Conception

Sammy sperm entering Emily egg...Sammy sperm entering Emily egg...

A few hours after conception

CLEAVAGE

ProphaseProphase

MetaphaseMetaphase

AnaphaseAnaphase

TelophaseTelophase

Mitosis Animation

G1 S G2 prophase metaphase

anaphase telophaseDaughter cells

Mitosis Animation

A profile of a person's chromosomes

Arranged and numbered by size, from largest to smallest

Used to identify chromosomal aberrationsthat may result in a genetic disorder

Abnormal positions of chromosomes, extra pieces ormissing 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

Nondisjunction

Chromosomal deletions

Chromosomal insertions

Chromosomal duplications

PolyploidyMost common is TrisomyCaused by Nondisjunction

15 30 45

Trisom

y

conc

eptio

ns

Mother’s Age Years

< 1%

35%

Down Syndrome Karyotype

Trisomy 21

Trisomy 13Patau

Syndrome

1 in 15,000 live birthsCondition is Lethal

Cleft PalateCleft Palate

Klinefelter Male

XXY occurs 1 in 1000 births

People with this disorder develop People with this disorder develop as males with subtle characteristics as males with subtle characteristics

that become apparent during puberty. that become apparent during puberty. They are often tall and usually do not They are often tall and usually do not develop secondary sex characteristics develop secondary sex characteristics

such as facial hair, such as facial hair, or underarm and pubic hair. or underarm and pubic hair.

Kleinfelter’s SyndromeTrisomy Animation

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

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.

Usually inherited as an autosomal dominant

Huntington’s DiseaseAutosomal Dominant Disorder

Brain Deterioration

Flo Hyman died from Marfan Syndrome

Autosomal Dominant

AFFECTSSkeletal System

Cardiovascular System Eyes...

Abraham LincolnMarfan Syndrome?

nn 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 certainGlands, 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 toUV light, skin cancer, early death

Tay-Sachs Disease = improper metabolism of gangliosides inNerve cells; early death

Albinism

No Pigmentation

is an Autosomal Recessive ConditionNo Expression of the Melatonin Genes

Hairy Ears is a Y-linked Trait. One allele produces non-hairy

ears

the other allele produces rather long hairs.

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 worksHow X-linked inheritance works

One Possible ScenarioOne Possible ScenarioThe female sex chromosomes The female sex chromosomes

of an unaffected mother of an unaffected mother (who carries an auditory condition)(who carries an auditory condition)

have one faulty gene have one faulty gene and one normal gene. and one normal gene.

The father has the The father has the normal gene on the X chromosome, normal gene on the X chromosome,

and a normal Y chromosome. and a normal Y chromosome.

HearsHears rR

R

R R

R

R

R R

Affected MaleAffected Male

Color Blindness: Sex Linked

What number do you see?

She Blinded me…X linked

#8

http://www.toledo-bend.com/colorblind/Ishihara.html

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.

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

Co-dominanceCo-dominanceBoth alleles are expressedBoth alleles are expressed

as Dominant in the heterozygoteas Dominant in the heterozygote

Intermediate/Incomplete DominanceIntermediate/Incomplete DominanceAlleles blend in the heterozygoteAlleles blend in the heterozygote