HUMAN GENETICS What can go wrong Chromosome Mutations

HUMAN GENETICS What can go wrong? Chromosome Mutations Gene Mutations

CHROMOSOME MUTATIONS Changes in chromosome number ______________ Missing chromosomes (monosomy) EX: Turner’s syndrome - X 0 ______________ 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 MUTATIONS If the change happens in a BODY CELL (lung, liver, brain, muscle, etc. ) = ___________ Somatic cell mutations can: Cause cancer ___________ Make cell not able to function ___________ Kill cell _______ v. BUT won’t be passed on to offspring

GERM CELL MUTATION If the change happens in Gametes (sperm & eggs) Germ cell mutation = ____________ v 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 Mutations 1. Point mutations – changes a _____ SINGLE base in DNA code 1. _________ Substitution 2. Frame shift mutations changes _______ MULTIPLE bases in code Deletion 1. __________ Addition 2. ________

SUBSTITUTION Changes one base for another ATTCGAGCT ATTCTAGCT

SICKLE CELL ANEMIA CAUSE: (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 ANEMIA SYMPTOMS: Sickle shaped Red Blood Cells in hh persons Circulatory problems Loss of blood cells (anemia) Organ damage DEATH

SICKLE CELL ANEMIA More 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 MUTATIONS Changes multiple bases in code thefatcatranandran the fat cat ran and ran __________ DELETION theatcatranandran 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

DUPLICATION Piece of DNA is copied too many times ________________________

FRAME SHIFT MUTATIONS Changes multiple bases in code thefatcatranandran the fat cat ran and ran __________ DUPLICATION thefatcatranandandran the fat cat ran and and ran ______________

HUNTINGTON’S CAUSE: Autosomal dominant 40 -100 CAG Repeats at end of gene on chromosome 4

HUNTINGTON’S SYMPTOMS: Seen in both males and females • 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

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 DISEASES AUTOSOMAL RECESSIVE • Phenylketonuria • Cystic fibrosis • Albinism • Hemophilia X-LINKED RECESSIVE • Color blindness AUTOSOMAL DOMINANT • Achondroplasia (Dwarfism)

HEMOPHILIA CAUSE: 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 births 200, 000 “little people” worldwide One of oldest known – seen in Egyptian art Normal size torso; short arms and legs Problem with way cartilage changes to bone as bones grow

COLOR BLINDNESS CAUSE: 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 Fibrosis Mutation in gene on chromosome 7 that codes for protein in membrane that transports chloride ions

Cystic Fibrosis Autosomal 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