1. PATTERNS OF INHERITANCE CAPTER 10

2. Pre-Mendel’s Theories  Blending Hypothesis: when parents with different traits have offspring, this will always show a blending of the traits  Spontaneous generation: Non-living matter giving rise to living matter  Homunculus: The little man inside the sperm

4.  Trait: a variation of a particular character  Particulate hypothesis: Parents pass on to their offspring separate and distinct factors (genes) that are responsible for inherited traits  Genetics: the study of heredity Mendel’s experiments with pea plants

5. Mendel’s experiments started with  True-breeding plants: when self- fertilized, a true-breeding plant produces offspring identical in appearance to itself generation after generation

6.  Cross-fertilization, sperm from the pollen of one flower fertilizes the eggs in the flower of a different plant

7.  the offspring of two different true-breeding varieties are called hybrids.

8. Monohybrid cross: pairing in which the parent plants differ in only one (mono) character.

10. Mendel’s principle of segregation  There are alternative forms of factors (genes) called alleles.  For each character, an organism has two alleles for the gene controlling that character, one from each parent. Homozygous = same alleles Heterozygous = different alleles

11. Principle of segregation (cont.)  When only one of the two different alleles in an heterozygous individual appears to affect the trait, that allele is called the dominant allele. The allele that does not appear to affect the trait is called the recessive allele  The two alleles for a character segregate (separate) during the formation of gametes (sex cells). Each gamete carries only one allele of each character (Principle of segregation)

12.  Phenotype refers to the observable trait (purple flowers)  Genotype refers to the combination of alleles (PP) Phenotypic ratio: ratio of plants with purple flowers to those with white flowers (3 purple : 1 white) Genotypic ratio: ratio of possible combinations of alleles (1 PP : 2 Pp : 1 pp)

13. Probability and Punnett Squares Probability: Chance of Something happening Punnett Square: Diagram used to show the probability of a genetic cross

14.  Phenotype refers to the observable trait (purple flowers)  Genotype refers to the combination of alleles (Pp)

15. Phenotypic ratio: ratio of plants with purple flowers to those with white flowers (3 purple : 1 white) Genotypic ratio: ratio of possible combinations of alleles (1 PP : 2 Pp : 1 pp)

16.  How can you find out the genotype of an individual showing the dominant trait?

17. TESTCROSS  In a testcross, an individual of unknown genotype, but dominant phenotype is crossed with a homozygous recessive individual

19. DIHYBRID CROSS  crossing of organisms differing in two characters

22. Principle of Independent Assortment  During gamete formation in an F2 cross, a particular allele for one character can be paired with either allele of another character  The alleles for different genes are sorted into the gametes independently of one another.

23. Not all traits are inherited following the patterns found by Mendel in pea plants  Intermediate or incomplete inheritance  Multiple alleles – codominance  Polygenic inheritance  Environment - epigenetics

24. Intermediate or incomplete inheritance The heterozygotes have a phenotype that is intermediate between the phenotypes of the two homozygotes

25. Multiple alleles - codominance For many genes several alleles exist in the population. Multiple alleles control the character of blood type in humans. There are six possible genotypes. The alleles I A and I B exhibit codominance, meaning that a heterozygote expresses both traits.

27. http://ww w.youtube.com/watc h?v=oz4Ct au8mC8

29. Polygenic inheritance  When two or more genes affect a single character  In humans, height and skin color have polygenic inheritance

30. Chromosome Theory of Inheritance  Genes are located on chromosomes  Behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns – (chromosomes undergo segregation and independent assortment during meiosis)

32.  Gene locus: location at which alleles of a gene reside on homologous chromosomes  Linked genes: genes that are located in the same region of a chromosome  Genetic linkage: tendency for the alleles on one chromosome to be inherited together. The closer two genes are on a chromosome, the greater the genetic linkage

34. Sex-Linked Genes (any gene located on sex chromosomes)  http://www.youtube.com/watch?v=vP_h08cT5jw http://www.youtube.com/watch?v=vP_h08cT5jw

36. Morgan's monohybrid cross for fly eye color produced a 3 : 1 phenotypic ratio of red to white eyes in the F2 generation. However, none of the flies with white eyes were female.