Human Genetics & Inheritance (p ) What do Geneticists use to study human traits & genetics diseases? Pedigrees: to analyze patterns of inheritance What is autosomal? occurs equally between males and females (chromosomes 1-22) sex-linked traits are usually only seen in males, most are recessive autosomal dominant traits, the parent will have it & each offspring with the trait will have it autosomal recessive traits, an offspring can have one, two or neither parent exhibit the trait

What is polygenic inheritance? influenced by several genes like: Skin color- 3 to 6 genes Eye color Height Hair color What are complex characters? Characteristics controlled by BOTH genes & environment What are multiple alleles? Two alleles are expressed (multiple alleles) in heterozygous individuals AKA Codominance Two alleles are expressed (multiple alleles) in heterozygous individuals AKA Codominance Example: BLOOD TYPES Example: BLOOD TYPES – type A= I A I A or I A i – type B= I B I B or I B i – type AB= I A I B – type O= ii

Type % of Population* Donates to... Receives from... A-6%A-/+, AB-/+A-, O- A+34%A+, AB+ A-/+, O-/+ B-2%B-/+, AB-/+B-, O- B+9%B+, AB+ B-/+, O-/+ AB-1%AB-/+A-, B-, AB-, O- AB+3%AB+ A-/+, B-/+, AB-/+,O-/+ O-7%A-/+, B-/+, AB-/+ O- O+38%A+, B+, AB+ O-/+ Blood Type Population FOUR basic types of blood -A, B, AB, & O Each with a positive & negative sub-type “+” (with) & “-” (without) indicate the presence/absence of Rhesus antigens

Parents:Parents: genotypesgenotypes = I A i & I B i phenotypesphenotypes = A & B Multiple Alleles I A iI A I B iiI B i IBIB i IAIA i

Sex Linked Traits XX chromosome - femaleXy chromosome - male fruit fly eye color

F 1 hybrids in betweenphenotypes F 1 hybrids have appearance in between the phenotypes of the two parental varietiesExample: SNAPDRAGONS (flower) red (RR) x white (rr) RR = red flower rr = white flower Incomplete Dominance

Sex Linked Traits Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) X R Y x X r X r Remember: – Y chromosome in males DOES NOT carry traits – Y chromosome - essentially limited to traits associated with being male – Sons will inherit an identical copy of his father's Y chromosome – contributions from multiple ancestors created by the reshuffling process of recombinationrecombination RR = red eyed Rr = red eyed rr = white eyed XY = male XX = female

Sex Linked Traits : the solution Do a Monohybrid Cross What is the outcome? 50% red eyed female 50% white eyed male

FEMALE CARRIER

Sex-Influenced Traits & Single-Allele Traits Sex-Influenced Traits Male Patterned Baldness Allele present in males controls the production of testosterone Higher levels produce baldness Single-Allele Traits Huntington’s Disease Autosomal Dominant More than 200 traits

Detecting Genetic Disease Genetic Screening Amniocentesis ? 14 th to 16 th week of pregnancy. Test fetal cells for chromosomes disorders and proteins in the fluid Chorionic Villi Sampling? sample of Chorionic Villi (cells derived from zygote and grow between uterus and placenta), 8 th -10 th week of pregnancy

Genetic Counseling Process of informing a person or couple about their genetic makeup Data from genetic screening tests and family pedigree are analyzed Predicts likelihood of offspring with genetic disorder

Genetic Disease Treatment Treatments: Treat the symptoms - Phenylketonuria (PKU), Cystic Fibrosis, Diabetes, Surgery Gene Therapy Replacing the defective gene Somatic cell gene therapy-treats body cells Germ cell gene therapy- treats sperm or eggs Debate: scientists view somatic cell gene therapy as normal medicine to improve an individuals health while germ cell gene therapy has no affect on the individual but on future offspring (Effect could be unpredictable)