1. Meiosis results in haploid cells through two cell divisions, reducing the chromosome number from diploid to haploid. During the first division, homologous chromosomes separate. The second division separates sister chromatids. 2. Genes encode proteins that produce traits, and can exist in different alleles. Genotypes describe an organism's allele makeup, while phenotypes describe observable traits. 3. Independent assortment of chromosomes and crossing over during meiosis increase genetic diversity by creating new combinations of genes in offspring.

1. KEY CONCEPT Gametes have half the number of chromosomes that body cells have.

2. sex cells (egg) body cells sex cells (sperm) You have body cells and gametes. Body cells are also called somatic cells. Germ cells develop into gametes. Germ cells are located in the ovaries and testes. Gametes are sex cells: egg and sperm. Gametes have DNA that can be passed to offspring.

4. Homologous pairs of chromosomes have the same structure.

5. For each homologous pair, one chromosome comes from each parent.

6. Chromosome pairs 1-22 are autosomes.

9. Gametes are haploid.

11. Many plants have more than two copies of each chromosome.

12. Mitosis and meiosis are types of nuclear division that make different types of cells.

14. Meiosis occurs in sex cells.

16. Cells go through two rounds of division in meiosis. Meiosis reduces chromosome number and creates genetic diversity.

18. Homologous chromosomes are similar but not identical.

19. Sister chromatids divide in meiosis II.

20. Sister chromatids are copies of the same chromosome.homologouschromosomes sister chromatids sister chromatids

24. Meiosis has two cell divisions while mitosis has one.

25. In mitosis, homologous chromosomes never pair up.

27. Sperm primarily contribute DNA to an embryo.

28. Eggs contribute DNA, cytoplasm, and organelles to an embryo.

30. Mendel laid the groundwork for genetics. Traits are distinguishing characteristics that are inherited. Genetics is the study of biological inheritance patterns and variation. Gregor Mendel showed that traits are inherited as discrete units. Many in Mendel’s day thought traits were blended.

31. Mendel’s data revealed patterns of inheritance. Mendel made three key decisions in his experiments. use of purebred plants control over breeding observation of seven“either-or” traits

33. P generation crossed to produce F1 generation

35. Among the F1 generation, all plants had purple flowers

36. F1 plants are all heterozygous

38. Traits are inherited as discrete units.

39. Organisms inherit two copies of each gene, one from each parent.

40. The two copies segregateduring gamete formation.

42. The same gene can have many versions. A gene is a piece of DNA that directs a cell to make a certain protein. Each gene has a locus, aspecific position on a pair ofhomologous chromosomes.

44. Homozygous describes two alleles that are the same at a specific locus.

47. A dominant allele is expressed as a phenotype when at least one allele is dominant.

48. A recessive allele is expressed as a phenotype only when two copies are present.

55. Sexual reproduction creates unique combinations of genes. Sexual reproduction creates unique combination of genes. independent assortment of chromosomes in meiosis random fertilization of gametes Unique phenotypes may give a reproductive advantage to some organisms.

56. Crossing over during meiosis increases genetic diversity. Crossing over is the exchange of chromosome segments between homologous chromosomes. occurs during prophase I of meiosis I results in new combinations of genes

58. The farther apart two genes are located on a chromosome, the more likely they are to be separated by crossing over.

59. Genes located close together on a chromosome tend to be inherited together, which is called genetic linkage.

60. Genetic linkage allows the distance between two genes to be calculated.