1. Mendelian Genetics chapter 10.1
As humans have altered ecosystems and caused species extinctions world-wide, a critical question is the extent to which such biotic modifications influence ecosystem-level processes.

2. Genetics
The study of heredity?

3. Who was Mendel? - Gregor Mendel Austrian monk
- Background in agriculture (grew up on a farm)

4. What did he do? He used garden peas Fertilization : Zygote:
Gametes: M & F sex cells
Fertilization :
Zygote:

5. The Male sex cells are the grains of pollen
Pollination ?
Garden peas are self pollinators ?
CROSS POLLINATION ?

6. Why did his experiments succeed?
He studied one trait at a time ( control experiment )
True breeding ?
True breeding tall pea plants & cross pollinated true breeding short pea plants .

7. Hybrid:
Monohybrids :

8. Results
Tall x Short
Tall
Tall x Tall
3 Tall x 1 short
Ratio 3 : 1

9. OTHER TRAITS Wrinkled or Round Yellow or Green
Results always: one trait did not appear in the F1 generation and then appears in one fourth of the F2 plants.

10. For these results Mendel determined that each organism has factors that control these results? Genes exist in alternative forms, such as, tall and short, round and wrinkled. The alternative forms are called alleles Mendel’s pea plants had two alleles for height.

11. But why did the offspring of a short plant crossed with a tall plant all grow into tall plants?
Mendel called the observed trait dominant and the trait that disappeared recessive.
In the F1 generation of plants each plant had one tall allele and one short allele. That is why the offspring of a tall and short plant were all tall.

13. scientists use the same letter for different alleles of the same trait.
An uppercase letter = dominant allele
lowercase letter = recessive allele.
T = dominant
t = shortness
dominant allele is always written first

14. Mendel created rules or laws to explain heredity.
law of segregation : every organism has two alleles of each gene and when gametes are produced the alleles separate.
Each gamete receives one of these alleles.
During fertilization, these gametes randomly pair to produce four combinations of alleles.

15. Two organisms can look alike but have different allele combinations.
The way an organism looks and behaves is called its phenotype
Ex: tall plant
The allele combination of an organism is called the genotype
Ex: TT or Tt.

16. An organism is homozygous for a trait if the two alleles for the trait are the same.
ex: TT or tt .
An organism is heterozygous for a trait if its two alleles for the trait are different from each other.
Ex: Tt

17. Mendel’s Dihybrid Crosses
A cross involving two different traits is called a dihybrid cross.
Mendel wanted to know whether, in a dihybrid cross, the two traits would stay together in the next generation, or whether they would be passed on independently of each other.
seed color and seed shape.

18. He cross pollinated true-breeding round, yellow seeds (RRYY ) with truebreedin wrinkled, green seeds (rryy). This created a dihybrid cross.
Results : F1 generation all the plants produced round yellow seeds.
When the F1 plants self-pollinated
Results : F2 generation ratio of phenotypes—9 round yellow, 3 round green, 3 wrinkled yellow, 1 wrinkled green.

19. Mendel created his second law of heredity, known as the law of independent assortment. This law states that genes for different traits are inherited independently of each other.
If the alleles for seed shape and color were inherited together, only two kinds of seeds would have been produced. Instead, four different kinds of seeds were produced

20. Punnett Squares
Reginald Punnett, an English biologist, came up with a way to predict the proportions of possible genotypes in offspring.
genotypes of the parents.

21. Probability
Punnett squares show all of the possible outcomes. Because chance is a factor in genetics, the actual results don’t always match the Punnett square’s probability.
It is like flipping a coin. The probability is 50/50 that the coin will be heads or tails. However if you flip a coin 100 times, you cannot guarantee that 50 times it will be heads and 50 times it will be tails. It is the same in genetics.
Even though a Punnett square may predict that one fourth of the offspring will have a particular genotype, in reality the amount could be higher or lower.

22. Meiosis chapter 10.2

23. Do now:
What is the different between a dominant and a recessive trait?
What was the results for the monohybrid and dihybrid cross?

24. Genes, Chromosomes, and Numbers
Genes determine individual traits.
Genes are lined up on chromosomes.
Ex: Mendel’s pea plants, it has 14 chromosomes, or seven pairs.
A cell that has two of each kind of chromosome is called a diploid cell.

25. In a diploid cell the two chromosomes of each pair are called homologous chromosomes.
Each chromosome of the pair has genes for the same traits in the same order.

27. Mendel concluded that parents give one allele of each trait to their offspring. That happens because the gamete is a haploid cell containing half the number of chromosomes as a body cell. Every living thing has a set number of chromosomes: ex:- dog has 78 chromosomes, human has 46 chromosomes tomato plant has 24 chromosomes

28. Do now:
What are the 5 stages of mitosis and what’s happening in each stage? Go back to your notes or use your textbook ( chapter 8)
How does a diploid cell become a haploid cell? How can an organism pass on half its chromosomes?

29. A haploid cell contains only one of each kind of chromosome.
ex: A gamete, or sex cell
How does a diploid cell become a haploid cell? How can an organism pass on half its chromosomes?

30. Meiosis produces gametes containing half the number of chromosomes as the parent’s body cell. meiosis I meiosis II The whole process begins with one diploid cell and ends with four haploid cells.

33. 1. ______Each new cell contains exactly the same genetic information as the parent
2. ______The resulting cell contains one chromosome from each pair
3. ______Results in the formation of one cell
4. ______The chromosome number increases from generation to generation
5. ______ Sex cells are formed
6. ______The resulting cells have half the number of chromosomes as the body cells
7. ______Two cells are produced at the end

34. ---------1. Phenotype a. The combination of gametes to form a zygote
Heterozygous b. All the visible characteristics of an organism
Fertilization c. Having two different alleles for a trait
Allele d. A specific part of a chromosome coding for a trait
Genotype e. Genetic make-up of an organism
Gene f. An organism only needs one copy of this allele to show the trait
Dominant g. Different forms of the same gene
Recessive h. Sex cell
Gamete i. Requires two copies of an allele to show the trait
Homozygous j. Having two identical alleles for a trait

35. Do now: Explain what is happening in this picture?

36. What is sexual reproduction?

37. - Male gametes are called sperm. - Female gametes are called eggs
- Male gametes are called sperm. - Female gametes are called eggs. When a sperm unites with, or fertilizes an egg, the resulting zygote has a diploid number of chromosomes. Then, using mitosis, the zygote becomes a multicellular organism. This way of reproducing, which involves producing and then uniting haploid sex cells, is called sexual reproduction.

38. What happens to homologous chromosomes during crossing over and what is the results ?

39. The chromosomes pair up with their homologous chromosomes near the middle of the cell. This pairing brings the two chromatids of each chromosome close together, making what is called a tetrad. The homologous chromosomes pair so tightly that sometimes a piece of a chromatid can break off. The piece changes places with a piece of the chromatid from the other homologous chromosome of the tetrad. This exchange is called crossing over. Crossing over can occur at several places at the same time.

40. Explain how crossing over and independent assortment play role in causing genetic variation in the gametes that results from meiosis?

41. genetic recombination.
The reassortment of genetic information that occurs during meiosis is called
genetic recombination.

42. Mistakes in meiosis
Nondisjunction: The failure of chromosomes to separate
chromosomes do not separate correctly.
gametes have too many chromosomes .
not enough chromosomes.

43. Gene Linkage and Maps
Genes on the same chromosome are usually linked and inherited together instead of independently. It is the chromosomes that follow Mendel’s law of independent assortment, not the genes. Linked genes can separate as a result of crossing over. Scientists have found that genes that are farther apart on a chromosome tend to cross over more often than genes that are close together. Using this information, scientists can make chromosome maps that show the sequence of genes on a chromosome.