1. Friday, November 2, 2007 The Cell and Inheritance Chapter 4, Section 3
BELLRINGER: What is meant by genotype and phenotype?

2. CHROMOSOMES & INHERITANCE Walter Sutton – American geneticist
Evidence
Grasshoppers:
24 chromosomes in body cells; 12 in sex cells
Hypothesis
Chromosomes are important in inheritance.
Fertilized egg has 24 chromosomes
Alleles exist in pairs in organisms

3. CHROMOSOMES & INHERITANCE
Walter Sutton – American geneticist
Grasshopper sex cells have half the number of chromosomes as body cells.
When grasshopper sex cells join, the fertilized egg has the same number of chromosomes as the body cells of the parents.

4. WHAT IS THE CHROMOSOME THEORY OF INHERITANCE?
Genes are carried from parents to their offspring on chromosomes.

5. MEIOSIS
The process by which the number of chromosomes is reduced to half to form sex cells – sperm and eggs.

9. A LINEUP OF GENES
The body cells of humans contain 23 chromosome pairs.
Genes are lined up in the same order on both chromosomes.