This document provides an introduction to genetics and how traits are passed from parents to offspring. It explains that genetics is the study of heredity and trait inheritance. It describes the key differences between body cells and sex cells, including that body cells have chromosomes in pairs while sex cells only have them in singles. It begins to explain how the number of chromosomes is important and differs between species, providing examples. It poses questions about which species have the most and least chromosomes. Finally, it defines what a gene is and how genes on chromosomes determine traits, and begins to describe fertilization and zygote formation between egg and sperm.

2. Back to
Basics

3. Enough fooling around. We get serious today. It’s time for GENETICS
GENETICS -
The study of how TRAITS are passed from PARENTS to
OFFSPRING
• Offspring usually show at least SOME traits of the
parents
• EVERYTHING we do in this chapter happens
in CELLS.

4. • Body Cell (somatic)
• Sex CEll (gamete)
• Makes up tissues and organs
• Makes Sperm or Egg
• Chromosomes in PAIRS
• Chromosomes in SINGLES

5. • The number of chromosomes in a cell really matters because ALL
living things have a very specific CHROMOSOME NUMBER.
For example . . .
• But that’s just us. Different species have different CHROMOSOME NUMBERS.
Turn the page and see if you can match the animal to the number of
chromosomes in its body cells . . .

6. 26

7. 38

8. 78

9. 36

10. 48

11. 34

12. Fascinating but does anyone know which animal has the MOST
chromosomes in its cells?
254

13. How about the animal with the LEAST chromosomes in its cells?
2

14. But remember ALL living things have CELLS and ALL cells have
CHROMOSOMES
768

15. 4

16. • No matter which organism you are looking at, All of their
chromosomes have GENES
GENE -
A specific section of a chromosome that DETERMINES a specific trait
SEX CELL
(gamete)
BODY CELL
(somatic)

17. Now let’s build on this Chromosomes having Genes stuff . . .
Mom’s Egg
Dad’s Sperm

18. • The sperm will fertilize the egg, and you will create a ZYGOTE
But what will this child look like?

19. To Be Continued . . .