6.3 Mendel and Heredity

1. 6.3 Mendel and Heredity How do physical traits we exhibit correspond to the DNA we inherit?

2. Recall: • Meiosis produces haploid cells. • How do these haploid cells become eggs and sprem?

3. Gametogenesis is the production of gametes. • Gametogenesis differs between females and males. • Sperm become streamlined and motile. • Sperm primarily contribute DNA to an embryo. • Eggs contribute DNA, cytoplasm, and organelles to an embryo. • During meiosis, the egg gets most of the contents; the other cells form polar bodies (which get broken down and recycled).

4. Fertilization is the combining of gametes. • Fertilization • Results in diploid cells. • Is a part of sexual reproduction. • Produces offspring that are genetically different from their parents. What determines how an offspring looks? • Genetics is the study of biological patterns of trait inheritance and genetic variation.

5. Mendel laid the groundwork for genetics. • Traits are distinguishing characteristics that are inherited. • Gregor Mendel, an Austrian monk, showed that traits are inherited as discrete units. • Many in Mendel’s day thought traits were blended. • He bred pea plants to research heredity.

6. Which of the following is an example of a biological trait? • personality • hair style • eye color • regional accent [Default] [MC Any] [MC All]

7. Why peas? • They reproduce quickly. • He had control over mating. • Mendel used purebred pea plants. This meant that a line of pea plants had self-pollinated for so long that they were genetically uniform. • He was able to breed selectively by interrupting and controlling the pollination process. • Because he used purebred pea plants, he knew that any genetic variation resulted from his experiments.

8. Mendel began his experiments with purebred pea plants. This approach enabled him to determine that variations among offspring were the result of • genetic uniformity. • self-pollination. • his crossings. • random mutations. [Default] [MC Any] [MC All]

9. Mendel controlled the fertilization of his pea plants by removing the male parts, or stamens. He then fertilized the female part, or pistil, with pollen from a different pea plant. • Mendel used pollen to fertilize selected pea plants. • interrupted the self-pollination process by removing male flower parts • the mating of two organisms is called a cross.

10. The P generation (parent) crossed to produce the F1generation (first filial, meaning 1st generation) • Mendel crossed a purebred purple flower with a purebred white • All F1 generation plants had purple flowers

11. Mendel allowed the resulting plants (F1) to self-pollinate, producing the F2 generation. • - White flowers appeared in some of the offspring. • - The trait for white flowers had not disappeared in the F1 generation, it had only been hidden, or masked.

12. Mendel did similar crosses focusing on other traits. • He determined which traits were dominant and which were recessive.

13. purple white • Mendel Learned: • Traits are inherited as discrete units. • This explains why individual traits persist without being blended or diluted over successive generations • Mendel discovered the law of segregation • Organisms inherit two copies of each gene, one from each parent. • The two copies segregate (separate)during gamete formation (meiosis).

14. When Mendel crossed plants that were purebred purple-flowered with plants that were purebred white-flowered, the resulting offspring all had purple flowers. When allowed to self-pollinate, this F generation gave rise to white-flowered plants as well as purple. As a result, Mendel determined that individual traits are • inherited as discrete units. • diluted in offspring. • merged with successive generations. • lost in the pollination process. [Default] [MC Any] [MC All]