1. Phenotype and Genotype

2. Early Ideas About Heredity
Heredity: the passing of traits from parent to offspring

3. Early Ideas About Heredity
Blending inheritance: offspring are a blend of genetic material from both parents.

4. Early Ideas About Heredity
People thought genetic material mixed or blended like colors of paint.

5. Early Ideas About Heredity
If blended inheritance were correct, populations would eventually look alike over many generations.

6. Early Ideas About Heredity
Blending inheritance doesn’t explain why some traits skip a generation.

7. Gregor Mendel
Genetics: the study of how traits are passed from parents to offspring.

8. Gregor Mendel Austrian monk with a fascination with biology
Conducted experiments by studying 7 different traits of pea plants.

9. Gregor Mendel
Recorded how the traits were passed from parent to offspring for several generations.

10. Gregor Mendel
Concluded that two “factors” control each trait.

11. Gregor Mendel
When organisms reproduce, each parent contributes one factor for each trait.

12. Dominant Factors
A genetic factor that “blocks” other factors is called dominant.
Represented by a capital letter
(Y for yellow)
(F for black fur)

13. Dominant Factors
A dominant trait is present if an organism has one or two dominant factors.
YY or Yy
FF or Ff

14. Recessive Factors
A genetic factor that is “hidden” by the dominant factor is called recessive.
Represented by a lowercase letter
(y for green)
(f for white fur)

15. Recessive Factors
A recessive trait is only present if an organism has two recessive factors. yy ff

16. Mendel’s Laws of Heredity
Law of segregation: the two “factors” for each trait separate from each other during meiosis.

17. Mendel’s Laws of Heredity
Law of independent assortment: the factors for one trait separate independently of how other factors separate

18. Mendel’s Laws of Heredity
Mendel didn’t know about DNA or how cells reproduce!
Still, his ideas formed the foundation of modern genetics.

19. Genes and Alleles
A gene is a section of DNA that has information about a trait in an organism.

20. Genes and Alleles
The different “types” or “versions” of a gene are called alleles.
Y or y
F or f

21. Genes and Alleles
Because eukaryotic chromosomes come in pairs, each gene has two alleles.

22. Genotype
The combination of alleles that an offspring gets from their parents is called its genotype.
YY or Yy or yy
FF or Ff or ff

23. Genotype
If both alleles in a genotype are the same, they are said to be homozygous.
FF or ff

24. Genotype
If the two alleles in a genotype are different, they are said to be heterozygous. Ff

25. Phenotype
The observable traits of an organism are its phenotype.

28. What is the passing of traits from parent to offspring?
Inheritance
Heredity
Genetics
Allele

29. What do you call the combination of alleles in an organism?
Genes
Genotype
Phenotype
Factors

30. If the two alleles on a gene are the same, it is called
Homologous
Recessive
Heterozygous
Homozygous

31. What type of trait can only be seen if it is homozygous?
Inherited
Dominant
Recessive
heterozygous

32. What is the idea that inheritance of one trait is not influenced by inheritance of another trait?
Law of Independent Assortment
Law of Segregation
Law of Heredity
Law of Maternal Inheritance