1. Chapter 7
Unit 5
Genetics

2. Essential Questions What are traits?
What is the difference between self-pollination and cross-pollination?
What were the steps of Mendel’s experiments?
What is a recessive allele and dominant allele?
Why do children look like their parents?
How do you use a punnett square?
What is the difference between a heterozygote and homozygote?
What is the difference between a genotype and phenotype?
What is a mutation and how do they cause disorders?
How is a pedigree used in genetic counseling?

3. 7-1 Genetics trait: a variation of a particular character
Ex yellow or red flowers
gene: a unit of inherited information

4. Gregor Mendel 19th century Austrian Monk
First to apply an experimental approach to the question of inheritance
genetics: the study of heredity
Used pea plant breeding

5. Pollination
pollination: the transfer of pollen from the male part to the female part of a plant (fertilization)
cross-pollination: pollen from one plant pollinates another plant
self-pollination: pollen from a plant pollinates itself

6. Mendel’s Experiment P generation= parental F1 generation = the hybrid
Purple or white flowers
Self-pollinate flowers to get
“pure” flowers
F1 generation = the hybrid
offspring
Cross-pollinated between
white and purple
All ended up purple
F2 generation = offspring when F1 self- fertilize each other
Purple flowers were self-pollinated
Ended up with 75% purple, 25% white

7. Mendel’s Pea Plants

8. Mendel’s Hypotheses There are alternate forms of genes
alleles: the alternate forms of genes
Ex. Purple and white
For each inherited character, an organism has 2 alleles for the gene controlling that character, one from each parent
homozygous: 2 alleles are the same for that character
heterozygous: the 2 alleles are different
3. dominant: only one allele appears to affect the trait recessive: the allele that does not appear to affect the trait
Pp; P = dominant, p = recessive

9. 7-2 Inheritance
Punnett square: Diagram that shows all possible outcomes of a genetic cross

10. Phenotype and Genotype
phenotype: an observable trait
Hair color, height, tongue rolling
The dominant trait shows up
Bb and BB = dominant; brown
bb = recessive; blond
genotype: the genetic makeup (combination of alleles)
1/2 Bb; 1/2 bb = 2:2

11. Importance in the Environment
Temperature can have an effect on animal coloring
Ex siamese cats, rabbits
Height can be affected by nutrition and exercise
Ex. Dancers
Nature vs Nurture

12. 7-3 Genetic Disorders mutation: change in genes
Can be harmful, helpful, or have no affect
mutagens: physical or chemical agents that cause mutations
Ex. High-energy radiation
Most genetic disorders are caused by harmful recessive alleles

13. Pedigree
pedigree: a family tree that records and traces the occurrence of a trait in a family
squares = males ; circles = females
colored shapes = individual with trait
half-colored = carrier
Genetic counselors: use pedigrees to predict chances of a disorder