1. Genetics: Inheritance

2. Meiosis: Summary
Diploid Cells (2n): Cells with two sets of chromosomes, (aka “homologous chromosomes”)
One set of chromosomes from each parent
normal body cells
Produced by mitosis
Haploid Cells (n): Cells with one set of chromosomes
Gametes or sex cells
Produced by meiosis
Meiosis: 2 rounds of cell division that produce cells with HALF the number of chromosomes

3. Mitosis vs. Meiosis

4. Some Definitions…. Genetics: The scientific study of heredity.
Trait: A specific characteristic of an individual. (For example??)
Gene:
Sequence of DNA that codes for a protein (and, therefore, a trait)
Passed down from parent to offspring
Allele: Different possible forms of a gene (one from each parent)
Homozygous: 2 of the same allele for the same gene
Heterozygous: different alleles for the same gene

5. Principle of Dominance
Definition: Some alleles are dominant and others are recessive
Which is the dominant allele for eye color, and which is the recessive?
Which are the dominant alleles and which are the recessive? How do you know?

6. Genotype vs. Phenotype
Genotype: the genetic makeup (i.e. combination of alleles for each particular gene)
Phenotype: the physical traits exhibited by an organism (observable)

7. Can we PREDICT which trait(s) will be inherited??
Probability: Definition??
Punnett Squares

8. Meiosis: How do we get genetic diversity?
Crossing Over: When homologous chromosomes pair up and chromatids cross over each other to exchange sections of DNA
How does this contribute to genetic variation?
Segregation: Chromosomes separate during meiosis, so that each cell from meiosis only contains HALF of the genetic material of the parent cell
Fertilization: When 2 haploid cells combine to form a zygote

9. Recessive Genetic Disorders
What common trends might genetic disorders have? (Think about what DNA and genes CODE for!)
Examples: Cystic Fibrosis, Tay Sachs Disease, Albinism
If a genetic disorder is RECESSIVE, what does that mean?
How might completely healthy parents have a child with a recessive genetic disorder?