CHAPTER 5 HEREDITY I Mendel and his peas

CHAPTER 5: HEREDITY I. Mendel and his peas • Heredity- passing of traits from parent to offspring II. Who was Gregor Mendel? • born in 1822 • from Austria • cultivated flowers and trees • worked in monastery garden • studied the way traits passed from parent to offspring • studied pea plants • studied one characteristic at a time; ex. plant height, pea color

III. Types of plants self-pollinating plant-contains both male and female reproductive structures; fertilizes itself true-breeding plant- self pollinates; always produces offspring with the same trait the parent plant has; ex. tall parent produces tall offspring cross-pollination- anthers of the plant are removed so the plant cannot self-pollinate; pollen from another plant is used to fertilize the original plant

Plant Characteristics • • • plant height; tall vs. short seed shape; round vs. wrinkled flower color; purple vs. white

Mendel’s first experiment • Dominant traits- the trait that appears and masks recessive traits • Recessive traits-the other trait that won’t be seen when the dominant trait is present.

Examples of dominant traits in humans: brown eyes tongue roller Dimples Brown hair unattached (free) earlobes freckles

Mendel’s second experiment • Mendel allowed dominant plants to self-pollinate • recessive traits still showed up • Ratio- Mendel calculated the number of dominant traits to recessive traits

Punnett Squares • • • used to visualize all the possible combinations of alleles from the parents dominant alleles are symbolized with capital letters recessive alleles are symbolized with lowercase letters genotype- inherited combination of alleles phenotype- organism’s appearance due to genes

Punnett Squares

Complete the Punnett Square below p P P pp= true-breeding white flower PP= true-breeding purple flower p

Probability probability- mathematical chance that an event • will occur; expressed as a fraction or percentage • What is the probability of seeing white flowered offspring? • What is the probability of seeing purple flowered offspring?

What is genetics? – – genes- segments of DNA that carry hereditary instructions and are passed from parent to offspring; located on chromosomes genes are made up of DNA that control all the traits that show up in an organism alleles- the different forms a gene may have for a trait genetics- the study of how alleles affect offspring and how traits are passed from one generation to the next.

DEFINITIONS – Innate behavior- behavior that an organism is born with and does not have to learn. • Ex. blinking – Learned behavior (learning)-the process of developing a behavior through experience or practice • Ex. language, a dog sitting on command – heterozygous-an organism that has 2 different alleles for a trait – homozygous- an organism that has 2 of the same alleles for a trait

What is a genome? Where is an organism’s genome found? A genome is the total amount of hereditary material in a single cell of an organism. It is found in the DNA of organisms.