1. Genetics: the study of heredity
Lesson 19
Genetics: the study of heredity

2. I. Genetics
Heredity: Passing of traits from one generation to the next
DNA: our genetic makeup

4. II. Meiosis Background
Phase which sex cells form and genetic information is passed into them
Homologs: chromosome pairs; contain genes for the same traits
Chromatids: chromosomes attached together by centromere
Chromosomes duplicate during interphase in cell cycle before meiosis

7. III. Meiosis I (4 phases) Prophase I: chromosomes shorten and thicken
Metaphase I: Chromosomes line up in the center of the cell
Anaphase I: Homologous pairs separate; chromatid pairs stay connected at centromere
Telophase I: cytoplasm pinches together forming 2 daughter cells with homologous pairs in each new cell

11. IV. Meiosis II (begins immediately)
Prophase II: chromatids move toward center
MetaphaseII: chromatids align in middle of cell
Anaphase II: Chromatids separate at centromere and move to opposite poles
Telophase II: two new daughter cells form  4 haploid cells

15. V. Terms to know Alleles: different forms of a gene
Genotype: genetic make-up for a trait
Homozygous: (pure) both genes in a pair are identical (ex: RR, rr)
Heterozygous: (hybrid) genes in a pair are different (ex: Rr)
Phenotype: way a trait is expressed

18. VI. Incomplete dominance
blended inheritance
Both genes expressed to a certain degree
Ex: Snapdragons
Homozygous Dominant RR (red) crossed with Homozygous Recessive (white) rr
Yields: Rr  pink color expressed

21. VII. Punnett Square Reginald C. Punnett
Made to display results of genetic crosses
Cross: random pairing of one gene from each pair from each parent

27. 19.2 reflection questions (pg 182 YB) – write answers only
Would each of your sex cells pass identical genes to an offspring?
Does the offspring express a trait that neither parent did? How is this possible?
How does meiosis result in four sex cells, each with one chromosome from each pair?