Genetics: the science of heredity “the study of the traits of organisms.” HEREDITY: the passing of traits from parents to offspring

Gregor Mendel-is known as the father of modern genetics. Mendelian Genetics. Gregor Mendel (1822-84) Known as the ‘father of genetics’ Austrian monk who carried out work using pea plants to study the inheritance.

Mendel's genius was that he noticed differences in peas being grown in his garden and applied the scientific method to determine the cause of these differences. Pick a characteristic shown here. What are the two traits for that characteristic?

He published a paper in 1865 with three conclusions to his research:

He published a paper in 1865 with these three conclusions to his research: Dominance and Recessiveness - One *factor in a pair may mask the effect of the other. *He called the traits “factors”…today we call them alleles

He published a paper in 1865 with these three conclusions to his research: Dominance and Recessiveness - One trait in a pair may mask the effect of the other. Law of Segregation - The two factors for a characteristic separate during the formation of eggs and sperm. Key points: Gregor Mendel studied inheritance of traits in pea plants. He proposed a model where pairs of "heritable elements," or genes, specified traits. Genes come in different versions, or alleles. A dominant allele hides arecessive allele and determines the organism's appearance. When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly. This is known as the law of segregation. A Punnett square can be used to predict genotypes (allele combinations) and phenotypes (observable traits) of offspring from genetic crosses. A test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous.

Mendel’s Laws of Inheritance Law of Dominance and Recessiveness - One factor in a pair may mask the effect of the other. Law of Segregation - The two factors for a characteristic separate during the formation of gametes (eggs and sperm). Law of Independent Assortment - The factors for different characteristics are distributed to reproductive cells independently. Mendel's law of independent assortment states that the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.

TEd (4 min.)…Ooh watch me, watch me

At the time of Mendel's work, chromosomes and the process of mitosis and meiosis were unknown.

Could this relate to your life? …Mendel's work was considered obscure and unimportant until 1900, when Walter Sutton proposed the Chromosome Theory. 35 years later… 1865  1900

Important genetic terms: Parents - the two organisms whose genes produce offspring. F1 generation - the offspring from parents. F2 generation - the offspring produced by crossing two F1 individuals. Monohybrid cross - a cross between individuals with one pair of contrasting genes. Dihybrid cross - a cross between individuals with two pairs of contrasting genes (heterozygous for 2 characteristics/genes).

MORE Important genetic terms: Genotype - the genetic makeup of an organism. (two alleles, a pair, one from each parent) Phenotype - the external appearance of an organism. Homozygous trait - the genes for that trait are the same. Heterozygous trait - the genes for that trait are not the same.

Examples of heterozygous / homozygous Homozygous  A, C, F, F Heterozygous  B, E, G ??? ??? Practice with VOCAB WS

Monohybrid Cross Homo-dom x Homo-res Hetero x Hetero Hetero x homo-dom

Freckles Homozygous Dominant X Homozygous Recessive f f Genotypic Ratio of F1: F Phenotypic Ratio of F1: F

Dimples Homozygous Recessive X Homozygous Recessive d d Punnett Squares Explained Dimples Homozygous Recessive X Homozygous Recessive d d Genotypic Ratio of F2: d Phenotypic Ratio of F2: d

Hair Color B ? B ? Heterozygous X Heterozygous

Hair Color Heterozygous X Heterozygous B b Genotypic Ratio of F2: B BB Phenotypic Ratio of F2: Bb bb b Heterozygous X Heterozygous

Dihybrid cross  2 characteristics/genes  2 traits/alleles for each characteristic  2 heterozygous genotypes crossed Examples  Pg. 282 in Text

DIHYBRID Heterozygous X Heterozygous Tall Round (TtRr) X Tall Round (TtRr) What are the possible combinations?

Guinea Pig Genetics! Practice away…

Study Help! READ 10.2 pg. 277 – 282 PDF of CH 1 MORE STUDY…

Quizlet Simple Vocab 10.2 w/Pics 10.2 FlashCards

Terms List: carcinogens, cell cycle, cells, DNA damage, genetic changes, spindle fiber failure, the sun’s ultraviolet rays, tobacco. 1. cells 2. genetic changes 3. DNA damage 4. spindle fiber failure 5. Carcinogens 6. cell cycle Note: Student answers for questions 7 and 8 are interchangeable. 7. tobacco 8. the Sun’s ultraviolet rays

SOURCE LINK SmartStarter For each genotype, indicate whether it is heterozygous (HE) or homozygous (HO)

1) For each genotype below, determine the phenotype. SmartStarter 1) For each genotype below, determine the phenotype.

2) For each genotype below, determine the phenotype. SmartStarter 2) For each genotype below, determine the phenotype.

SmartStarter For each phenotype, list the genotypes. (Remember to use the letter of the dominant trait)

SmartStarter Set up the square for each of the crosses listed below. The trait being studied is round seeds (dominant) and wrinkled seeds (recessive)

SmartStarter Set up the square for each of the crosses listed below. The trait being studied is round seeds (dominant) and wrinkled seeds (recessive)

SmartStarter Set up the square for each of the crosses listed below. The trait being studied is round seeds (dominant) and wrinkled seeds (recessive)

SmartStarter A homozygous dominant round seeded plant is crossed with a homozygous recessive wrinkled seeded plant. What are the genotypes of the parents? __________ x __________ What percentage of the offspring will also be homozygous? ______________

SmartStarter In guinea pigs, the allele for short hair is dominant. 1) What genotype would a heterozygous short haired guinea pig have? 2) What genotype would a pure-bred short haired guinea pig have? 3) What genotype would a long haired guinea pig have? BONUS Two short haired guinea pigs are mated several times. Out of 100 offspring, 25 of them have long hair. What are the probable genotypes of the parents? ________ x ___________ Show the cross to prove it!

SmartStarter