1. Ch. 4 Sec 3: Cells and inheritance
Key Concepts:
What role do chromosomes play in inheritance?
What events occur during meiosis?
What is the relationship between chromosomes and genes?
Key term:
Meiosis

2. So, like, basically..
There was a guy named Sutton in 1903 that wanted to know how sex cells (sperm and egg) form.
He found out that sex cells have half as many chromosomes as regular body cells. When they joined, they resulted in cells with the correct number of chromosomes.

3. Sutton’s theory
Alleles exist in pairs in organisms. One allele comes from the female parent and one allele comes from the male parent. Paired alleles are carried on paired chromosomes.
Chromosome theory of inheritance – genes are carried from parents to their offspring on chromosomes.

4. How do sex cells end up with half the number of chromosomes?

5. Meiosis
Meiosis is the process by which the number of chromosomes in a cell is reduced to half to form sex cells.
Chromosome pairs separate and are distributed to two different cells. Those cells are then divided again, and each resulting sex cell has half the number of chromosomes.
When sex cells combine to form an organism, each sex cell contributes its chromosome number. Thus the offspring gets the normal total of chromosomes.

7. What you need to know about meiosis:
Similar to mitosis, but:
UNLIKE mitosis, which results in two identical daughter cells, MEIOSIS allows for genetic recombination (just from its design). It results in sex cells (UNLIKE mitosis, which is somatic, or body, or non-sex cells) with HALF the number of chromosomes.
Why is it important that they end up with half the number of chromosomes?

8. Genes
Chromosomes are made up of many genes joined together. Genes are sections of DNA that contain information to code for proteins.
******Plants and animal cells typically have two copies of every gene because they have one on each chromosome.
******An inherited trait can be the result of one or several genes
Sexual reproduction results in offspring receiving half their genes from each parent. ******

9. Homozygous – organism that has two identical alleles
Heterozygous – organism with two different alleles

10. Geneeeeees???
Questions on genes?

11. What should you know so far?
Key terms
What Mendel did
What dominant and recessive alleles are
What a Punnett square is
What phenotype/genotype are