Copy the chart: Quick Question 1/31 Physical GENETIC Traits (SPECIFIC!) Similarities Differences 1) 2) 3) 4) 5)

Figure 13.1 Figure 13.1 What accounts for family resemblance?

Genetics Assignments: Ch. 9 Vocab – DUE Friday, 2/2 Ch. 9 Objectives – DUE Monday, 2/5 Family Photo and Character Traits List (5 similarities/5 differences) – DUE BLOCK Tues 2/6 or Weds 2/7

GENETICS: Patterns of Inheritance Chapter 9 GENETICS: Patterns of Inheritance

Genetics is the scientific study of heredity and variation Living organisms are distinguished by their ability to reproduce their own kind Genetics is the scientific study of heredity and variation Heredity is the transmission of traits from one generation to the next “The DNA Journey” Variation is demonstrated by the differences in appearance that offspring show from parents and siblings © 2011 Pearson Education, Inc.

The historical roots of genetics: Early 19th century: traits from mom and dad blend like paints to form kid’s traits Gregor Mendel (1840’s) : “Father of modern genetics” Mendel crossed pea plants that differed in certain characteristics (traits) and traced from generation to generation; used a mathematical approach Why did he choose pea plants? Crossing of traits: Self fertilize (True breed) – cross pollen and egg from same parent plant to get identical offspring Cross Fertilize (hybrid) – cross pollen from one parent plant with the egg of a different parent plant Gregor mendel

And so on… P generation is true-breeding – Parent generation F1 generation = Hybrid offspring of P (parents) F2 generation = offspring of F1 plants crossed F3 generation = offspring of F2 plants crossed And so on… Parents (P) White Purple Offspring (F1)

Genes- units that determine heritable traits *Genes are segments of DNA on a chromosome, which code for EACH different trait Flower color Flower position Seed color Seed shape Pod color Pod shape Stem length Purple White Axial Terminal Round Wrinkled Inflated Constricted Tall Dwarf Green Yellow

For each characteristic (trait), an organism inherits 2 alleles, one from each parent. Think of TRAITS as CATEGORIES and ALLELES as OPTIONS within each category! P generation (true-breeding parents) F1 generation F2 generation Purple flowers White flowers  All plants have purple flowers Fertilization among F1 plants (F1  F1) of plants have purple flowers 3 4 of plants have white flowers 1 Examples: Flower Color (trait) Purple or White (alleles)

Phenotype = physical appearance of the allele for a specific trait (purple/white flower for flower color trait) Genotype = genetic makeup the alleles that represent the phenotype (one dominant, one recessive; or 2 dominant alleles and 2 recessives) DNA from the Beginning Animations

Dominant and Recessive Alleles: If the 2 alleles of an inherited pair are different, then one determines the organism’s appearance and is called the dominant allele. (Dominant will usually show up more often!) The other allele has no noticeable effect on the organism’s appearance and is called the recessive allele. (Is present but does not show up in the appearance) * If dominant allele is present, it takes over and outweighs the recessive!

Dominant and Recessive alleles: CAPITAL letters = DOMINANT alleles lower case letters = recessive alleles. *MUST USE SAME LETTER FOR EACH TRAIT! (Doesn’t matter the letter you choose!) Example: Flower Color (trait) T = purple, t = white Pea Color R=yellow, r =green

HOMOZYGOUS and HETEROZYGOUS When 2 of the SAME ALLELES are present, it is HOMOZYGOUS for that trait. HH = homozygous dominant hh = homozygous recessive When 2 DIFFERENT alleles are present, it is termed HETEROZYGOUS for the trait. Hh= heterozygous With homozygous, you must clarify which allele- either Dominant or recessive!

PUNNETT SQUARE: Shows a genetic mixing (cross) of alleles from both parents for specific traits. Used to PREDICT PROBABILITIES and see inheritance patterns for specific traits!

Trait= Flower Color H h Parent #2 H =purple h = white Hh Hh Hh Hh #1 Hh Hh

Probability of one offspring from parent cross! Trait= Flower Color * If Dominant allele is present, it takes over and outweighs the recessive! H =purple h = white H h Genotype =genetic makeup (represented by letters!) Parent 1 = hh homozygous recessive Parent 2 = HH homozygous dominant Offspring= 100% Hh Heterozygous Hh Hh Probability of one offspring from parent cross! Phenotype =physical appearance (what the letters represent!) Hh Parent 1 = white Parent 2 = purple Offspring= 100% purple Hh

LET’S PRACTICE!!!

9.8 Genetic traits in humans can be tracked through family pedigrees. Pedigree Key Dd Joshua Lambert Abigail Linnell D ? John Eddy Hepzibah Daggett dd Jonathan Elizabeth Dd Dd dd Dd Dd Dd dd Female Male Deaf Hearing Female Male Mating Offspring Figure 9.8 B

Recessive Disorders- Most human genetic disorders are recessive Parents Offspring Sperm Normal Dd  D d Eggs D d DD (carrier) dd Deaf Figure 9.9 A

Pea Plant Inheritance Patterns- Complete Dominance

Homologous chromosomes bear the two alleles for each TRAIT Each trait has the same locus (point) on homologous chromosomes Genotype: RR aa Bb Heterozygous R a b B Gene loci Recessive allele Dominant allele Homozygous for the dominant allele Homozygous for the recessive allele Flower Color? Pea Color? Plant Height?

Mendel’s 2 Main Laws of Inheritance 1) Law of Segregation (separate)- allele pairs from each parent separate from each other during the production of gametes (sperm/eggs) Mendel’s 2 Main Laws of Inheritance

Mendel’s 2 Main Laws of Inheritance 2) Law of Independent Assortment- States that alleles of ONE trait separate independently of allele pairs from a DIFFERENT TRAIT during gamete formation (more than one trait involved) *During meiosis, various combinations can end up in the different gametes, so all possibilities for trait phenotypes! Mendel’s 2 Main Laws of Inheritance

Table 9.9

Dominant Disorders- Some human genetic disorders are dominant Parents Offspring Sperm Dwarf Dd Normal dd  D d Eggs d Achondroplasia – cause of dwarfism Figure 9.9 B

9.10 New technologies can provide insight into genetic legacy Identifying Carriers For an increasing number of genetic disorders, tests are available that can distinguish carriers of genetic disorders and can provide insight for reproductive decisions Fetal Testing: Amniocentesis and chorionic villus sampling (CVS) allow doctors to remove fetal cells that can be tested for genetic abnormalities Fetal Imaging- Ultrasound imaging uses sound waves to produce a picture of the fetus

Chorionic villus sampling (CVS) Figure 9.10 A Amniocentesis Chorionic villus sampling (CVS) Ultrasound monitor Fetus Uterus Amniotic fluid Fetal cells Several weeks Biochemical tests hours Cervix Suction tube inserted through cervix to extract tissue from chorionic villi Needle inserted through abdomen to extract amniotic fluid Centrifugation Placenta Chorionic villi Karyotyping

Ethical Considerations Newborn Screening Some genetic disorders can be detected at birth, by simple tests that are now routinely performed in most hospitals in the United States Ethical Considerations New technologies such as fetal imaging and testing raise new ethical questions (Think about “Designer Babies”!)

NON-MENDELIAN GENETICS ALL OF THE FOLLOWING ARE EXCEPTIONS TO MENDEL’S RULES!!! Mendel’s principles are valid for all sexually reproducing species, HOWEVER, genotype often does NOT dictate phenotype in the simple way his laws described.

9.11-9.23 NON-MENDELIAN GENETIC PATTERNS When an offspring’s phenotype in the heterozygous in between the phenotypes of its parents. (3rd phenotype shows up!) P generation F1 generation F2 generation Red RR Gametes  White rr Sperm Eggs Pink Rr R r rR 1 2 Incomplete dominance EXAMPLES: Roses, Snapdragons Figure 9.12 A

9.11-9.23 NON-MENDELIAN GENETIC PATTERNS In a population, when 2 or more allele options exist for a single trait. Codominance EXAMPLES: Roan Fur, Speckled Chickens, AB Blood Type Figure 9.12 A

9.11-9.23 NON-MENDELIAN GENETIC PATTERNS In a population, when 2 or more allele options exist for a single trait. Multiple Alleles EXAMPLES: ABO Blood Types AB Type is also CODOMINANT! Figure 9.12 A

Figure 9.13

9.11-9.23 NON-MENDELIAN GENETIC PATTERNS Alleles found on more than one gene location; creates a multiple variations of phenotypes Polygenic EXAMPLES: Human Skin Color

9.11-9.23 NON-MENDELIAN GENETIC PATTERNS pattern of sex-linked genes is visible in one sex over the other, females or males. Typically on X chromosome Males receiving a single X-linked allele from his mother will have the disorder Female has to receive the mutated allele from both parents to be affected Sex Linked EXAMPLES: Baldness, Hemophilia

Examples: Hemophilia, Color Blindness, and Duchenne Muscular Dystrophy Sex Linked Most sex-linked human disorders are due to recessive alleles and are mostly seen in males Examples: Hemophilia, Color Blindness, and Duchenne Muscular Dystrophy Queen victoria Albert Alice Louis Alexandra Czar Nicholas II of Russia Alexis Figure 9.24 A Figure 9.24 B

Example: Hypertrichosis Pinnae Auris Sex Linked Linked to Y chromosome (only males) Example: Hypertrichosis Pinnae Auris (aka HAIRY EARS!!!)

Extra Credit Questions regarding talk will be on the Ch. 9 Test! Watch “The Ethical Dilemma of Designer Babies” TED Talk on class website! Extra Credit Questions regarding talk will be on the Ch. 9 Test!