1. Mendelian Introduction
Oct 23, 2013

2. Definitions to know
Trait: specific characteristic that varies from one individual to another
Gene: sequence of DNA that codes for a protein and thus determines a trait
Allele: one of a number of different forms of a gene
Genotype: genetic makeup of an organism
Phenotype: physical characteristics of organism

3. Alleles
The principle of dominance states that some alleles are dominant and others are recessive
Dominant alleles are indicated (usually) by a capital letter
An organism with a dominant trait will always exhibit that trait
An organism will only exhibit the recessive trait if no dominant allele is present

4. Gregor Mendel
Quick research (page 263) 1) Who is Gregor Mendel? Provide a brief biography 2) What did he use to carry out his work? 3) What did he discover?
Make notes of anything that is important!

5. Gregor Mendel
Priest in Czech Republic had a garden worked with garden peas true-breeding: self-pollination would produce identical copies of themselves

6. Mendel’s Peas
Mendel studied plant traits (chart on page 264) Original pair of plants the P generation offspring are called F1 of First Filial generation
Offspring of crosses b/w parents of different traits are called hybrids.

7. Mendel’s Conclusions
Biological inheritance is determined by factors that are passed from one generation to the next
- GENES - different forms of genes are alleles
2) Principle of dominance: states that some alleles are dominant and others are recessive

8. Segregation
Had the recessive alleles disappeared? F1 hybrids reproduced to make F2 generation
F1 cross: traits controlled by recessive alleles had returned ¼ of F2 plants showed recessive traits when each F1 plant flowers and produces gametes the two alleles segregate from each other so that each gamete carries only a single copy of each gene.

9. Punnett Squares Probability: likelihood that an event will occur
If you flip a coin 3 times what is probability that it will land on heads every time? ½ X ½ X ½ = 1/8
The principles of probability can be used to predict the outcomes of genetic crosses

10. Punnett squares
Shows the gene combinations that might result from a genetic cross
Used to predict and compare the genetic variations that will result from a cross

11. Terminology
Homozygous: organisms that have two identical alleles for a particular trait - said to be true-breeding
Heterozygous: two different alleles for same trait - hybrid for a particular trait

12. Terminology
Phenotype: physical characteristics - what the organism looks like
Genotype: genetic makeup

13. Probability and Segregation
Can be determined by Punnett squares
Probabilities predict the average outcome of a large number of events

14. Independent Work
Read page Record Definitions of Independent Assortment Complete Dominance Incomplete Dominance Codominance Multiple Alleles Polygenetic Traits Answer question 4 on page 274