1. Section Notes
Visuals and Notes

2. 3.1 Focusing Questions
What is the difference between DNA, Genes, and Chromosomes?
How many chromosomes do humans have in their body cells?

3. DNA: Deoxyribonucleic acid
All together, it is the genetic material found in the nucleus of every cell in your body. It is the “blueprint” for who you are as the coded sequence of chemicals, inherited from your parents, stores the information about the specific traits that you have.

4. 4 chemicals that make up DNA

6. A look at the pairs of chromosomes in body cells…

7. Genes
segment (piece) of DNA on a chromosome that codes (has a specific combination of chemicals) for a specific trait (characteristic)

8. Relationship between DNA, Genes, and Chromosomes
In the nucleus of body cells,
humans have 23 pairs of
chromosomes (46 in total)

9. 3.2 Focusing Questions
(3) What's so special about gametes? What is the process called that forms them?
(4) What is each stage in sexual reproduction called and how many chromosomes does each stage have?

10. “Cell division” is a silly name
“Cell division” is a silly name. We are making more…shouldn’t it be called “cell addition”??
To make more body cells, all human cells go through mitosis
To make more gametes, human cells go through meiosis

11. Mi-“toe”-sis Original Body Cell – In humans, 46 chromosomes
What other process does
this remind you of?
Mi-“toe”-sis
DNA then splits
DNA doubles itself
Original Body Cell – In humans, 46 chromosomes
or 23 pairs
New Cell: with 46 chromosomes
or 23 pairs

12. Mei-“ovary”-sis Careful: this process creates gametes !!
Start with 46 chromosomes
at the beginning of meiosis, or 23 pairs
Finish with 23 individual chromosomes
at the end of meiosis

13. So how do I answer that weird chart question in the booklet…..
This number would be the same as a body cell because mitosis
is the process that creates new body cells
Meiosis is the process that splits the number of chromosomes
in half, so a gamete would have half the number of a body cell
Zygote is just the first body cell

14. What is each stage in sexual reproduction called?

15. 3.3 Focusing Questions
(5) How did my 2 black cats just produce a white cat?

16. Important Definitions
Parents: two organisms passing along their traits to offspring Offspring: an organism created from the genetic combination of two organisms through reproduction Traits: Characteristics passed down from parents to an offspring (Ex: eye color, ear lobes)

17. Punnett Squares: Chart used to predict the outcome of two parents reproducing Allele: Spot on a chromosome where a gene is located. We use a letter used to describe genetic information for a trait. Typically two alleles per trait. (Example; “A” for not albino, “a” for albino)

18. Purebred / Homozygous: is a term used to describe two of the same allele (Example; AA or aa). Hybrid / Heterozygous: is a term to describe two different alleles for the same trait. (Example; Aa).

19. Dominant: Allele that masks or hides the recessive allele when the combination is heterozygous. (Example; the ‘A’ in Aa). Recessive: Allele that is hidden or masked by a dominant allele, unless both alleles are recessive. (Example; the ‘a’ in Aa).

22. Incomplete Dominance: when neither allele is dominant and instead of one being expressed, they both combine and create a mixture of the two.
Example: When you mate a homozygous red rose with a homozygous white rose, you end up with a heterozygous pink rose.