1. SB2. Students will analyze how biological traits are passed on to successive generations
Using Mendel’s laws explain the roles of meiosis in reproductive variability
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

2. Vocabulary Law of independent assortment Law of segregation
Law of dominance
Heredity
Genetic recombination
Dominant
Recessive
Allele
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

3. How do Mendel’s Laws explain how variations arise in sexually reproducing organisms?

4. Gregor Mendel
Austrian monk that paved the way for our current understanding of DNA
Studied how garden peas’ traits were passed from one generation to the next
Called heredity
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

5. He used this information to develop his 3 laws:
Mendel’s Laws
Through his work with pea plants Mendel discovered some trends that increased genetic variability in offspring.
He used this information to develop his 3 laws:
Law of dominance
Law of independent assortment
Law of segregation
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

6. Law of Dominance
Why don’t I express all the traits of both of my parents if I have genes from both parents?
All inherited traits are NOT expressed
Some genes are dominant over others
One form of a gene is dominant over another so the other trait is hidden (recessive).
Both genes (one from dad, one from mom) are still present but you will only express one trait.
So, for each gene only one trait can appear in the next generation.
Example: eye color: brown is dominant to blue (recessive)
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

7. Brown fur is dominant to white
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

8. Law of Independent Assortment
Does a gene for one trait have anything to do with whether I inherit a gene for a different trait?
NO—the traits/genes are not linked.
Completely Random
If you remember from MEIOSIS:
During gamete formation…
Genes for traits found on different chromosomes separate INDEPENDENTLY.
INDEPENDENTLY means apart from all others
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

9. Chromosomes separate randomly and independent from each other
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

10. Law of Segregation What does segregation mean?
SEPARATE!
Genes or alleles are separated in the parents and then passed on to the offspring:
If you remember from MEIOSIS:
During gamete formation…
Pairs of homologous chromosomes separate and are distributed to different gametes so that each gamete receives only one member of the pair
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

11. The genes for trait G/g separate so that each gametes only gets one gene for each trait
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

12. Summarize During the process of meiosis gametes are formed
Each gamete contains a unique set of chromosomes. (genetically different)
Law of segregation, Law of independent assortment
When two gametes join to form a zygote during fertilization (sperm + egg = zygote) the chromosomes from each parent are combined to form the chromosomes of the offspring.
Genetic recombination
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

13. Summarize The offspring has a collection of genes from both parents.
Some of the genes are dominant over other genes.
Law of dominance
The genes that are dominant will be expressed in the offspring.
The genes that are not dominant will remain on the chromosomes but will not be expressed.
However they can be passed onto the next generation
And could possibly be expressed in the offspring
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

14. Concept Check
1. Which law states that organisms inherit two copies of each genes and donate one copy to each of their offspring?
a. Law of dominance
b. Law of segregation
c. Law of independent assortment
d. Law of inheritance
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

15. Concept Check
2. Mendel’s second law of genetics, the law of independent assortment, is one explanation of the
a. random fertilization of gametes
b. genetic variation within species
c. greater strength of dominant alleles
d. final stages of gametogenesis
How do Mendel's Laws explain how variations arise in sexually reproducing organisms?

16. Types of Inheritance
Terminology that you need to know in order to predict the inheritance of traits:
Allele
Dominant and Recessive
Homozygous and Heterozygous
Genotype and Phenotype
Punnett Square

17. The same gene can have many versions.
Allele
Allele
alternative form of a gene
Each gene has a locus, a specific position on a pair of homologous chromosomes.
Alleles can be represented using letters.
A, B, C, ……
The same gene can have many versions.

18. Dominant and Recessive
Dominant allele mask the recessive allele from being expressed.
Dominant alleles are represented by uppercase letters A
Recessive allele is the allele that is masked by the dominant trait.
recessive alleles by lowercase letters a
Only expressed when both alleles are recessive

19. Homozygous and Heterozygous
Each parent donates one allele for every gene.
Homozygous- two alleles that are the same at a specific locus. (AA or aa)
Heterozygous- two alleles that are different at a specific locus. (Aa)

20. Phenotype and Genotype
Physical characteristic
What you can see:
Color (Green or yellow)
Height (tall or short)
Shape (round or wrinkled)
Genotype
Genetic make up of the organisms
What alleles it has:
GG, Gg, gg
TT, Tt, tt
RR, Rr, rr
Phenotype:
GREEN
Genotype:
GG or Gg
Phenotype:
Yellow
Genotype: gg