1. Fundamentals of Genetics

2. Genetics
The field of Biology devoted to understanding how characteristics are transmitted from parents to offspring.

3. Gene
A segment of DNA that contains coding for a polypeptide or protein
A unit of hereditary information.

4. Heredity
The transmission of characteristics from parents to offspring.

5. Discussion-Mendel’s Data WS
How are traits inherited?
Where does a person get their eye color, hair color, and so on?
What if one parent has brown hair and the other one is blond? What hair color will their children have?

6. Gregor Mendel Austrian monk who experimented with garden peas
Used knowledge of statistics and studied heredity
Known as the father
of genetics

8. Pollination
Self -Pollination
Cross-Pollination
Web Link

9. A Brief History
In the past, people did not understand how traits were inherited, but there were many guesses based on things that could be observed. Two theories emerged….

10. Theories Blending Theory - offspring are a straight mix
Particulate Theory - traits are inherited as "particles", offspring receive a "piece" from each parent, some pieces may hide the others
Tall x Short = Hybrid

11. Mendel Video 3 min On Mendel’s Data WS Read Introduction
Bozeman Science 0-3:42

12. One Monk’s Boredom Part 1 – Story Time!!
read pp In “What’s in Your Genes?” book.

13. Mendel’s First (P1 to F1)
In the first set of experiments, Mendel conducted cross-pollination between a pure breeding tall plant and a pure breeding dwarf plant. He collected the seeds from this cross pollination and allowed them to germinate. All the resulting plants were found to be tall.
P1 to F1
generation

14. Next he…
In a similar pollination between a pure breeding plant with purple flowers and a pure breeding plant with white flowers, all the resulting plants of the next generation produced only purple flowers.
F1 generation

15. Probability
Probability: the likelihood that a specific event will occur.
May be expressed as a decimal, %, fraction, or ratio
Probability= # of actual times
# of opportunities

16. Punnett Squares Practice

17. Principle of Dominance
Based on these results, Mendel came to the conclusion that in a cross-involving two contrasting characters, only one character expresses itself in the next generation.
Mendel called the character, which expressed as dominant character and the character, which failed to express, as recessive character. This idea came to be known as the principle of dominance (first law).

18. F2 Generation
At this stage, Mendel wanted to know whether the tall plants resulting from a cross between tall and dwarf plants, were similar to the tall plants of the P1 generation. Hence, he allowed the tall plants of the F1 generation to undergo self- pollination. In the next generation, Mendel found both tall plants and dwarf plants.
The results were most surprising since the recessive character dwarfness had reappeared in the next generation. (F2 generation)

19. Mendel discovered that each trait is controlled by two factors (alleles)
Genes – factors that determine your traits
Genes are located on chromosomes
Locus – the location of a single gene on a chromosome

20. Dominant factor: masks the other factor for a specific characteristic
Recessive factor: has no observable effect on an organism’s appearance when paired with a dominant factor. The hidden factor.

21. Genotype and Phenotype
Genotype: the genetic makeup of an organism. Consists of the alleles that the organism inherits from its parents
Purple flowered plants PP or Pp
White flowered plants pp

22. Phenotype: the appearance of an organism as a result of its genotype.
PP or Pp = purple flowers
pp = white flowers

23. GENOTYPE  -  what genes, letters, the organism has (TT, Tt, tt)
Homozygous: same Letters (TT or tt)
Heterozygous: different letters (Tt)
PHENOTYPE   - what it looks like (tall or short)

24. Mendel’s Garden Peas
Observed 7 characteristics of pea plants. Each characteristic occurred in 2 contrasting traits.

25. Characteristic Trait Plant height long/short stems Flower position axial/terminal Pod color green/yellow Flower Color purple/white Pea Shape round/wrinkled Pod shape inflated/constricted Pea Color yellow/green WS

26. Example: Mendel’s experiments – the dominant trait of yellow seed color in F2 generation occurred 6022 times, the recessive trait of green seed color appeared 2001 times. Total # of individuals = 8023
Probability of Dominant trait
6022 / 8023 = 0.75 or 75%, ¾, 3:4
Probability of Recessive trait
2001 / 8023 = 0.25 or 25%, ¼, 1:4

27. P= Parent
F1=first Filial cross
F2 =second Filial Cross
Mendel’s monohybrid
3:1 ratio

28. Mendel’s Results and Conclusions
Crossed green pods with yellow pods (P1)
All green pods produced (F1)
¾ green pods and ¼ yellow pods (F2)
Finish Mendel’s WS

29. Mendel’s Results and Conclusions
Hypothesized that something within the pea plants controlled the characteristics he observed – called these “factors”
Said that each trait was inherited by the means of a separate factor. Reasoned that there must be a pair of factors controlling each trait because the characteristics he studied had 2 alternative forms.

30. Recessive and Dominant Traits
When Mendel crossed strains, one of the P1 traits failed to appear in the F1 plants but reappeared in a 3:1 ratio in the F2 generation.
Mendel concluded that one factor in a pair may prevent the other from having an effect.

31. Human phenotypes can appear to be altered: hair dye, colored contact lenses, surgery, etc but they do not alter the individual’s true phenotypes or genotype.
Colored Contact Lenses

32. Homozygous: when both alleles of a pair are alike.
PP= homozygous dominant
pp= homozygous recessive
Heterozygous: when the two alleles in the pair are different.
Pp= heterozygous for flower color.
Video (1.5 minutes)

33. Test Cross
An individual of unknown genotype is crossed with a homozygous recessive individual (bb).
Can be used to determine the genotype of any individual whose phenotype is dominant. If one of the offspring turns up with the recessive trait, then you know the unknown parent is heterozygous (Bb).

34. The Law of Segregation
States that a pair of factors segregate or separate during formation of gametes (reproductive cells).
Each gamete receives only one factor of each pair
When two gametes combine during fertilization, the offspring have two factors controlling a specific trait

35. The Law of Independent Assortment
States that factors for different characteristics are distributed to gametes independently.

36. The Law of Independent Assortment
Mendel crossed plants that differed in two characteristics such as flower color and seed color.
Data showed that traits from dominant factors do not necessarily appear together.
Factors for different characteristics are not connected.

37. Most of Mendel’s findings agree with what biologists now know about molecular genetics.