Chapter 4 : Patterns of Heredity

1. Chapter 4:Patterns of Heredity Section 1: Living things inherit traits in patterns.

2. Inherited Traits • Traits passed down from your parents • Genetically linked

3. Acquired Traits • Something gained or learn during your lifetime • Not genetically linked

5. Heredity • is the passing of genes from parents to offspring • These genes code for the expression of traits. • an organism does not inherit the traits ONLY the genes for the traits • Some characteristics are affected by many genes in complicated ways.

6. alleles a gene Homologs • Most eukaryotic cells contain pairs of chromosomes, with one chromosome of each pair coming from each of two parents. • The chromosomes in a pair are called homologs. • They resemble each other, having the same size and shape, and carrying genetic information for particular traits.

7. alleles a gene Alleles • An alternate form of a gene for a specific trait or gene product. • Ex) in the picture A or a are different alleles for the same gene • Ex) Tongue roller and non-tongue roller are different alleles for people

8. alleles a gene Gene • The basic unit of heredity that consists of a segment of DNA on a chromosome. • Are sites that code for particular traits such as eye color, hair color, etc.

9. Each species has a characteristic number of chromosomes. • Chimpanzees have 24 pairs of chromosomes (48 total) • Fruit flies have 4 pairs of chromosomes (8 total) • Humans have 23 pairs (46 total)

10. What’s special about the 23rd pair? • The 23rd pair are the sex chromosomes. • In humans, the sex chromosomes are called the X-chromosome and the Y-chromosome. • A human female = XX • A human male = XY

11. Describes the actual characteristics that can be observed P for Picture of what the genes “look” like Ex.) Brown hair, Blue eyes The name for the genes an organism has. Describe an organisms specific alleles Ex.) Aa, AA, aa Phenotype vs. Genotype

12. More prominent, more powerful, stronger alleles Usually represented by a capital letter Only needs 1 allele to control the phenotype Has the power to mask (hide) recessive alleles Less prominent, less powerful, weaker alleles Usually represented by a lower case letter Needs 2 alleles to control the phenotype Can not mask dominant alleles Dominant vs. Recessive

13. Having 2 of the same alleles in the genotype BB – Homozygous Dominant bb – Homozygous recessive Also known as a PURE BREED Having 2 different alleles in the genotype Bb – Heterozygous Also known as a HYBRID Homozygous vs. Heterozygous

14. Gregor Mendel • A monk, trained in science and math, who lived in Austria during the mid- 1800s • Performed the first major experiments investigating heredity • Began investigating the inheritance of traits among the pea plants in the his garden • Separately worked with seven different traits: • plant height flower and pod position, seed shape, seed color, pod shape, pod color, and flower color.

15. Mendel Experiments • Mendel noticed variations in the heights of pea plants • So he purposely crossed (mated) pea plants that were pure-breed dwarf & pure-breed regular to see what their offspring would become Regular x Dwarf T T x t t

16. First generation (F1 ) • After crossing a true-breeding regular pea plant with a true-breeding dwarf pea plant • all regular pea plants were produced in the first generation. • Two of these plants were then crossed to produce a second generation F1 generation all regular (Tt)

17. Second generation (F2 ) • After allowing the first generation pea plants to cross • ¾ regular pea plants (TT & Tt) and ¼ dwarf pea (tt) plants were produced 1 Regular (TT), 2 Regular (Tt), & 1 Dwarf (tt) were produced

18. So What?!? • Mendel drew upon his knowledge of mathematics while analyzing his data in order to suggest a hypothesis that would explain the patterns he observed.Mendel realized that each plant must have two “factors” for each possible trait, one factor from each parent. Some traits, such as dwarf height, could be masked—dwarf height could be seen in the

19. Chapter 4:Patterns of Heredity Section 2: Patterns of heredity can be predicted

20. Punnett Square • Illustrates how the parent’s genes can possibly combine mom's genotype dad's genotype = offspring's possible genotype

21. Ratio • Compare 2 different quantities (numbers) • Ex) Ratio of boys to girls = 10 to 7 or 10:7 • # order depends on the wording

22. Probability • The chance or likelihood of an event or something happening

23. Percentage • Compares the probability of something to 100 • Ex) 93% of the questions on a test were correct

24. Incomplete dominance • Also known as “Co-dominance” • Is when there are 2 different dominant alleles which share power • Ex) RW = pink in poinsettias

25. Dihybrid Crosses • Deals with 2 genotypes at once • Includes 4 alleles • Brown Hair = B • Blonde Hair = b • Brown eyes = Q • Blue eyes q

26. BQ Bq bQ bq BQ Bq bQ bq

27. Chapter 4:Patterns of Heredity Section 4.3: Meiosis is a special form of cell division

28. Gamete • Special cells that contain only half the number of chromosomes in a normal cell of that organism • Also known as “1n” cells, haploid or sex cells • In a female their gametes are referred to as eggs • In males, gametes are referred to as sperm

29. Body Cells • Are normal typical cells • Ex) skin, or muscle cells • Also known as “2n cells” or diploid cells

30. Fertilization • The process that takes place when the egg and the sperm combine to form one new “2n cell”

31. Meiosis • Special kind of cell division that produces haploid cells • Involves a single cell going through 2 divisions • Meiosis I & Meiosis II

32. Meiosis II Meiosis I 1n 1n 1n 1n How meiosis works… • At the beginning of meiosis I, the parent cell has made two copies of each chromosome pair. • During meiosis I, the homologs of the chromosome pair separate; there are two cells, each with two copies of one homolog from each pair. • During meiosis II, the two copies of each homolog separate; each daughter cell has one homolog.

33. Mitosis Meiosis • Produces 4 daughter cells • Splits twice • Daughter cells have ½ the parents genetic info (DNA) • Produces 1n cell, haploid cells, gamete or sex cells • Has 8 main stages • Produces 2 daughter cells • Splits once • Parent and daughter cells genetically identical • Produces 2n cell, diploid cells or body cells • Has 4 main stages • Starts with a single cell • Are forms of cell division • Happens in stages • Chromosomes (DNA) only copied 1 time