1. 1 The Cell Cycle

2. S1-1-13 Describe the relationships among DNA, chromosomes, genes, and the expression of traits. S1-1-01 Illustrate and explain the process of mitotic cell division in plants and animals. Vocabulary & People ChromosomesDNAGenes TraitHeredityInterphase MitosisCytokinesis

3. The nucleus of every cell contains a set of chromosomes. Made of DNA shaped as twisted “double helix” DNA is an acronym – DeoxyriboNucleic Acid

4. All of your genetic information is coded in the DNA – like a book called “How to build YOU” Gene – section of DNA that codes for a specific trait – hair colour, height, eye colour… A single gene codes for a single trait Trait – a specific feature or characteristic that varies between individuals

5. 44 “regular” chromosomes 2 “sex” chromosomes (because they determine the sex) There are 2 types of sex chromosomes – “X” and “Y” In human cells, a complete “set” means all 46 chromosomes containing about 30 000 genes. The information in all 46 chromosomes is called the human “genome”

6. The 46 chromosomes can be arranged as 23 pairs

7. A complete picture of your genome – is called a Karyotype

8. Heredity – the passing on of genetic traits from individual to offspring. Individuals carry two copies of every gene (1 from mother– 1 from father) This is why the chromosomes can be paired up

9. Books = 46 chromosomes Pages = DNA Chapters = 30 000 gene

10. Modern Cell Theory can be summarized as: 1.The cell is the basic unit of life. 2.All living things are made of one or more cells. 3.All cells come from pre-existing cells. One-cell organism: amoeba One-cell bacteria: E. coli Tree leaf cells Human skin cells

11. So all “new” cells are reproduced from “old” cells

12. Why Do Cells Divide? 1.Growth – Increase in the number of cells 2.Healing and Repair – Replace damaged cells You replace about 25 million old cells every second 3.Reproduction – Pass on genetic information

13. The “life of a cell” consists of a sequence of steps called the Cell Cycle: Cell cycle has two parts: 1. Interphase 2. Division phase

14. Interphase Longest phase Living life and preparing for eventual division Chromosomes (46 books) must be copied

15. 2. Cytokinesis - dividing cytoplasm and organelles. Division phase - consists of two parts: 1. Mitosis - division of chromosomes and nucleus. Giving both cells a complete set of “books” Mitosis is how all new somatic (body) cells are made End Result: Two identical cells that re-enter interphase begin the process again.

16. End Result: Two identical cells that re-enter interphase begin the process again. Interphase Despite this graphic, remember: interphase (preparation) takes the longest

17. CAN YOU ANSWER THESE QUESTIONS? S1-1-13: How are the terms DNA, chromosome, genes and trait connected? S1-1-01: Why do cells divide and how does it work? Vocabulary & People ChromosomesDNAGenes TraitHeredityInterphase MitosisCytokinesis