1. April 4th, Day 3
Obj: You will be able to identify the pros and cons of genetic technology & develop a personal viewpoint.
Do Now: What were we doing/learning about before spring break?
HW: Chapter 11 Reading Assignment due Thursday

2. April 5th, Day 4
Obj: You will be able to describe Mendel’s experiments and the conclusions he drew from them.
Do Now: What is the first thing that comes to mind when you hear the word “genetics”?
HW: Chapter 11 Reading Assignment due Thursday

3. Introduction to Genetics
Chapter 11
Introduction to Genetics

4. Gregor Mendel Considered the “Father of Genetics”
Performed Experiments to Study Heredity
Heredity – the passing of traits or characteristics from parent to offspring
In his experiments Mendel used Pea Plants.
Why?

5. Mendel’s Pea Plants Cheap & Readily Available
Easy to Grow & Don’t Move (easy to contain & control/manage)
Grow fast –study multiple generations
Control their breeding/reproduction
Characteristics were easy to study because they came in easily identifiable pairs.
Round vs. Wrinkled Pea Shape
Tall vs. Short Pea Plants
Green vs. Yellow Pea Pods

6. Mendel’s Experiment
Mendel controlled the reproduction of his pea plants so he could study heredity.
He did this by:
Removing the Stamen (male)
Contains the Anther
Pollen = Plant Sperm
Carpel (contains the stigma, style, ovary) – female reproductive structures
Crossed Plants that showed the same traits only.
Created “true or pure bred” lines

7. Mendel’s Experiment
Once Mendel had his true or pure bred lines, he could cross plants that had different traits.
What did Mendel look for?
Patterns!

8. Observations
So what did Mendel observe when he performed his experiments?
________________ X ___________________
All _________________________
____________________ x ______________________
Ratio
3 ( ) __________________: 1 ( ) _________________

9. Dominant vs. Recessive
Traits like pea shape are said to be either dominant or recessive.
A recessive trait become hidden by a dominant trait.
In Mendel’s cross which trait was dominant?
Which trait was recessive?
How do we know recessive traits are present & get passed down?

10. Mendel didn’t know anything about Genes!
Gene – segment of DNA that codes for a specific protein which controls a trait.
Genes can exist in more than one form!
For example
Round or Wrinkled are 2 forms of the gene or protein for seed shape.
We call these different forms of a gene: alleles
Each parent has 2 alleles for each trait BUT only gives one to the offspring!
Which one? That’s all chance!

11. Probability & Genetics
Diploid Organisms have 2 copies of each numbers chromosome.
Remember, chromosomes of the same shape and size are called:
Homologous Chromosomes
Homologous Chromosomes carry the same genes but can have different forms or alleles of these genes.
For Example:
Both chromosomes 18 carry the gene that controls the shape of your hair line. (one chromosome 18 came from mom & one from dad)
18 A – Widow’s Peak
18 B – No Widow’s Peak
So, which one will you pass on to your child?

12. Probability & Genetics
Scientists can make predictions about which traits will get passed onto offspring & therefore what offspring might look like.
The study of these predications is called probability.
Probability
Expressed as a fraction or a percent.
Equation: # of times a specific event occurs
total # of possible outcomes
can be either dependent or independent

13. Inheritance of Alleles
Mendel crossed plants that differed in one gene/trait: pea shape.
This type of cross is called a monohybrid cross.
________________ X ___________________
All _________________________
____________________ x ______________________
Ratio
3 ( ) __________________: 1 ( ) _________________

14. Generations & Punnett Squares
The plants involved in the 1st cross are called the parental or P generation.
The offspring of the P generation are called the F1 generation.
The offspring of the F1 generation are called the F2 generation.
Punnett Square
Capital Letter represents the: Dominant Allele
Lowercase Letter represents the: Recessive Allele
Place each parent’s allele combinations across the top & side of the box & fill in the squares.

15. Genotypes & Phenotypes
Both RR pea plants & Rr peal plants look round, but are they the same genetically?
Round is called a phenotype = physical appearance
Rr or RR is called a genotype = actually genes or alleles of an individual
Two Types of Genotypes
Homozygous = two identical alleles (RR or rr)
Heterozygous = two different alleles (Rr)

16. Genotypes & Phenotypes
Classify the following as either a genotype or phenotype. For each genotype determine if it is homozygous or heterozygous. RR Round Rr

17. Genotypes, Phenotypes, & Punnett Squares
Every time you make a Punnett Square you MUST indicate both the Phenotypic & Genotypic Ratios!
Let’s do an Example: homozygous round pea X heterozygous round pea