Genetics Heredity  passing down of traits or characteristics from _____________________ Genetics  study of _________________

Gregor Mendel ( ) Worked with ___________________. 2 major traits for each plant Plants were either _________________________

Mendel’s Experiment Male and Female sex organs in pea plants are on the _________________ (___________have pollen and ______________ contains the egg) Pure Traits  Traits established through _______________________ Stamen  Stigma  Stigma

Genetics Pure white individuals x pure purple individualsPure white individuals x pure purple individuals F1  ____________________________F1  ____________________________ F1 x F1  ______ ratio of purple to white pea plantsF1 x F1  ______ ratio of purple to white pea plants Out of 1000 plants ______________ were purple and _______________ were whiteOut of 1000 plants ______________ were purple and _______________ were white Results of the Parental cross showed that one trait _______________________ the other traitResults of the Parental cross showed that one trait _______________________ the other trait X=

Genetics Vocabulary Dominant Trait  Trait that _______________ the recessive trait Recessive Trait  Trait that is ___________________ up In this cross PURPLE color was dominant

Mendel’s Hypothesis Gene  sequence of ___________ on a chromosome Each pea plant trait is a combination of _________genes, one from __________ and one from ____________ Each alternative gene is called an ______________ Dominant Gene  shown by a capital letter (P) Recessive Gene  shown by a lower case letter (p) Pure Purple plants  ________ Pure white plants  _______ PP x pp  all _________ Pp x Pp  ____________________________

Mendel’s Terms Homozygous  2 of the same allele (PP or pp) Heterozygous  2 different alleles (Pp) Punnett Square  Results of a cross can be predicted

Incomplete Dominance Some traits do not have dominant alleles Heterozygotes appear as a mix between 2 parents 1 trait = ___ phenotypes 4 O’clock Flowers Rr x Rr Ratio of Offspring 1 _______ 2 _______ 1 _______

Codominance Neither allele is dominant Presence of heterozygote means both alleles are _________________________ ____________________is an example

Sex Determination Thomas Morgan discovered that chromosomes differed in males and females Females- ______ Males- ________ Called _______ Chromosomes All other chromosomes are called __________

Sex-linked Inheritance Morgan crossed _________ male with _______________ female F1Ratio: _________________ F2 Ratio: 3:1 ratio, but ______ any white females Reasoned that there are genes on __________chromosomes Allele for eye color is on ______chromosome No gene for eye color on ______ chromosome Presence of homozygous recessive, or ONLY a _______________, yields recessive trait Morgan’s Crosses

Sex Influenced Traits (Not on test!) Sex-influenced traits are autosomal traits that are influenced by sex. If a male has one recessive allele, he will show that trait, but it will take two recessive for the female to show that same trait. One such gene is baldness. BB  normal male & female Bb  bald male; normal female bb  bald male; bald female

Dihybrid Crosses Dihybrid Cross: Cross: Cross of 2 individuals for 2 different traits Example: In Pea Plants Tall(T) is dominant to short Purple(P) is dominant to white Crossing homozygous tall, purple plant with a homozygous short, white plant _______________ Crossing heterozygous tall, purple plant with a heterozygous tall, purple plant TtPp x TtPp

Pedigrees & Genetic Diseases Autosomal dominant disease  Presence of dominant allele means that _________________________________________ Autosomal recessive disease  Disease only present when ______________recessive alleles are present Sex-linked Dominant  Disease present when dominant allele is present on ______________________________ Sex-linked Recessive  Disease present when recessive allele is ________________________________

Common Genetic Diseases Huntington’s Disease  ___________________________; ____________________; degeneration of muscle tissue; onset in early 30’s. Folk Singer Woody Guthrie had the disease Cystic Fibrosis  _______________________________; Defective Protein is made that creates excess mucus; clogs lungs. Color Blindness  _________________________________ Inablity to distinguish colors (_______________of male population)

Some Genetics Diseases Hemophilia  Sex-linked recessive __________________________ Nicholas, Czar of Russia (Mid 1800’s) child was _________________________ Muscular Dystrophy  _______________________ Tay-Sach’s Disease  _______________________ Degeneration of _____________________; infant mortality

Changes in Chromosome Number Nondisjunction – occurs when: In meiosis I, homologous pair both go into the same daughter cell or In meiosis II, the sister chromatids both go into the same gamete. The result: ___________ (3 copies of a single chromosome) or ___________ (1 copy of a single chromosome)

Nondisjunction in meiosis I

Changes in Chromosome Structure Mutation - a permanent ____________________. Chromosome mutation - a change in _____________________structure Radiation, organic chemicals, or even viruses may cause chromosomes to break, leading to mutations. Types of chromosomal mutations: inversion, translocation, deletion, and duplication.

Deletions Deletions occur when a single break causes a ___________, or two breaks result in a loss in the interior. An individual inherits a normal chromosome from one parent and a chromosome with ______________from the other parent No longer has a pair of ______________________ A syndrome can result – type depends on chromosome(s) affected.

Williams Syndrome Chromosome ________________________ Children have a pixie look (turned-up noses, wide mouth, small chin, large ears) Poor academic skills, good verbal and musical abilities Skin ages prematurely from lack of the gene that controls the production of elastin (also affects cardiovascular health).

Duplication Duplication results in a chromosome segment being __________________________________ Produces extra alleles for a trait. Ex: An inverted duplication in chromosome 15 causes inv dup 15 syndrome Poor muscle tone, mental retardation, seizures, curved spine, and autistic characteristics

Duplication

Translocation Translocation is _________________________________ between two, non-homologous chromosomes. Ex: Alagille syndrome results from a deletion of chromosome 20 or a translocation that disrupts an allele on chromosome 20. Distinctive face, abnormalities of eyes & internal organs, and severe itching.

Translocation

Inversion Inversion involves a segment of a chromosome being ____________________________ The reverse sequence of alleles can alter gene activity. Crossing-over between inverted and normal chromosomes can cause duplications and deletions in resulting chromosomes.

Inversion