HUMAN GENETICS What can go wrong? Chromosome Gene Mutations Mutations

Missing chromosomes (monosomy) EX: Turner’s syndrome - X0 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 MUTATIONS If 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 Mutations 1. Point mutations – changes a _________ base in DNA code 1. __________________ 2. Frame shift mutations changes _____________ bases in code 1. ___________________ 2. ________________ SINGLE Substitution MULTIPLE Deletion Addition

SUBSTITUTION A T T C T A G C T 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 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 ____________________ 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

DUPLICATION Piece of DNA is copied too many times ________________________________________________

FRAME SHIFT MUTATIONS Changes multiple bases in code thefatcatranandran ____________________ DUPLICATION thefatcatranandandandandran ___________________________ the fat cat ran and ran the fat cat ran and 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