HUMAN GENETICSWhat can go wrong?

Chromosome GeneMutations Mutations

CHROMOSOME MUTATIONS Changes in chromosome number

____________________________

____________________________

Missing chromosomes (monosomy) EX: Turner’s syndrome - X0

Extra chromosomes (trisomy) EX: Down’s syndrome – 3 #21’s Kleinfelter’s syndrome- XXy

GENE MUTATIONS Changes in the DNA code of a single gene

SOMATIC CELL MUTATIONSIf the change happens in a BODY CELL

(lung, liver, brain, muscle, etc.)

= ______________________

Somatic cell mutations can: ______________________

______________________

_____________

Somatic cell mutation

Cause cancer

Make cell not able to function

Kill cell

BUT won’t be passed on to offspring

GERM CELL MUTATION If the change happens in Gametes

(sperm & eggs)

= _______________________Germ cell mutation

Can be passed on to offspring

MUTATIONS can be:

____________________________

____________________________

____________________________

Beneficial –

Gives organism a trait that helps it to survive Provides a way for species to change

Harmful – Genetic disease, cancer

Lethal – Causes DEATH (often before birth)

Harmful Gene Mutations1. Point mutations – changes a _________ base in DNA code 1. __________________

2. Frame shift mutationschanges _____________ bases in code

1. ___________________

2. ________________

SINGLE

MULTIPLE

Substitution

Deletion

Addition

SUBSTITUTION

Changes one base for another

A T T C G A G C T

A T T C T A G C T

SICKLE CELL ANEMIACAUSE:

(autosomal recessive)

A changed to T (glu to val)

gene on chromosome #11 that codes for part of hemoglobin protein (carries oxygen in blood)

SICKLE CELL ANEMIASYMPTOMS:Sickle shaped Red Blood Cells in hh persons

Circulatory problemsLoss of blood cells (anemia)Organ damageDEATH

SICKLE CELL ANEMIAMore common in African Americans 1 in 500 = hh 1 in 10 = Hh carriers for gene

Hh persons have Sickle cell TRAIT make some normal RBC’s’ ; some

sickled cells

DELETION________________________________________ Piece of DNA code is lost

FRAME SHIFT MUTATIONSChanges multiple bases in code

thefatcatranandran

____________________

DELETION

theatcatranandran

_____________________

the fat cat ran and ran

the atc atr ana ndr an

Duchenne Muscular Dystrophy

CAUSE: (X linked recessive) deletion in gene

that codes for a muscle protein

Duchenne Muscular Dystrophy (DMD)

SYMPTOMS: 1 in 3500 male births Appears before age 5 Progressive muscle weakening Most in wheelchair by age 13 Eventually lethal

DUPLICATIONPiece of DNA is copied too many times________________________________________________

FRAME SHIFT MUTATIONSChanges multiple bases in code thefatcatranandran

____________________

DUPLICATION

thefatcatranandandandandran

___________________________

the fat cat ran and ran

the fat cat ran and and and ran

HUNTINGTON’S

40-100 CAG Repeats at end of gene on chromosome 4

CAUSE: Autosomal dominant

HUNTINGTON’S

• Degenerative brain disorder

• Symptoms appear age 30-40 (Usually after having children) • Lose ability to walk, think, talk,

reason

• 50/50 chance of passing it to child

SYMPTOMS: Seen in both males and females

Until now people didn’t know they had the gene, until after they had already had children.

Now there is a test to tell if you have the gene before symptoms appear.

Would you want to know if there is NO cure?

INVERSION

Segment flips and reads backwards

OTHER GENETIC DISEASESAUTOSOMAL RECESSIVE

• Phenylketonuria

• Cystic fibrosis

• Albinism

• Hemophilia

X-LINKED RECESSIVE

• Color blindness

AUTOSOMAL DOMINANT

• Achondroplasia (Dwarfism)

HEMOPHILIACAUSE:

change in gene on X chromosome that codes for blood clotting protein

SYMPTOMS: More common in males Internal and external bleeding Can result in death transfusions/hospitalization required frequently to stop bleeding

ACHONDROPLASIA(Dwarfism)

CAUSE: (Autosomal recessive-chromosome 4)Most new mutations in egg or sperm cell, but can be inherited from parent with gene

1 in 20,000 births200,000 “little people” worldwideOne of oldest known – seen in Egyptian artNormal size torso; short arms and legsProblem with way cartilage changes to bone as bones grow

COLOR BLINDNESSCAUSE:

X linked recessive

Mutation in gene on X chromosome

SYMPTOMS:More common in males (8% of males are colorblind)Can’t distinguish certain colors Most common = red/green

Cystic FibrosisMutation in gene on chromosome 7 that

codes for protein in membrane that transports chloride ions

Cystic FibrosisAutosomal recessive Symptoms:

More common in Caucasians

Make extra thick mucous in lungs and pancreas which leads to respiratory and digestive complications

Salty skin is clue

Phenylketonuria (PKU) CAUSE:

Mutation in gene for enzyme that changes the amino acid phenylalanine into tyrosine

Build up causes brain damage

ALL babies have blood test for PKU when born before leaving hospital

Treatment: Diet low in phenylalanine can extend life and prevent retardation * Nutri-sweet warning