1. What are the characteristics of living things?

2. Limits to Cell Growth
Why does a cell divide instead of growing indefinitely?

3. Limits to Cell Growth
Why does a cell divide instead of growing indefinitely?
The larger a cell becomes the more demands the cell places on its DNA
Trouble moving enough nutrients and wastes across the cell membrane

4. Cell Growth & Reproduction
Mitosis & Meiosis

5. Fun Facts
Cell Growth Rate: If left unchecked E. coli could engulf the Earth in one day because it doubles in volume every 30 minutes
Some cells divide more than others
Ex. Brain, nerve, heart cells—rarely divide
Skin cells—always dividing

6. Chromosomes Made of DNA and carry the genetic information
Each chromosome consists of two identical sister chromatids
Each pair of chromatids is attached at the centromere

7. Why can’t you mate your dog and cat and get a cog or a dat?
Chromosomes must pair up perfectly in organisms in order to successfully produce offspring.

8. The Number of Chromosomes Differ Depending on the Organism
Dogs have 78
Cats have 32
Humans have 46
Carrots have 18
Fish have 94
Amoeba have 50
Lettuce has 18

9. The Cell Cycle The series of events that cells go through as they grow and divide

10. Five Phases of the Cell Cycle
Interphase
G1: Gap 1
S: Synthesis
G2: Gap 2
M: Mitosis
C: Cytokinesis

11. Interphase G1: cells grow and make more cytoplasm and organelles
S: DNA is replicated
G2: all structures needed for division are made (ex. centrioles)

12. M Phase: Mitosis Division of the nucleus Only occurs in eukaryotes
Uncontrolled cell growth leads to cancer

13. Prophase Cell spends 60% of it’s time here
Chromatin condenses and becomes visible
Nuclear envelope disappears
Centrioles pull apart
Spindle forms

14. Metaphase Shortest phase of replication
Chromosomes line up across the center of the cell
Microtubules connect the centromere to spindle poles

15. Anaphase
Centromeres split and sister chromatids are pulled towards opposite poles

16. Telophase Nuclear membrane reforms around each set of chromosomes
Chromosomes uncoil
Mitosis is complete!

17. Cytokinesis Division of the cytoplasm into two new cells
Two nuclei form
Animal Cells: cell membrane is drawn inward (cleavage furrow) until the cytoplasm is pinched into two
Plant Cells: cell plate forms and develops into cell wall

18. Cytokinesis

19. Meiosis

20. Important Vocabulary
Meiosis- a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell
Homologous pair: each chromosome that came from mom has a corresponding chromosome that came from dad
Diploid(2N): a cell that contains both sets of homologous chromosomes
(ex. Human body cells—46)
Haploid(N): a cell that contains a single set of chromosomes
(ex. gametes of sexually reproducing organisms/ human egg cell—23 and human sperm—23)

21. Meiosis I Interphase I: DNA Replication
Prophase I: each chromosome pairs with its corresponding homologous chromosome to form a tetrad(4)
Crossing Over-the exchange of portions of their chromatids
Metaphase I: spindle fibers attach to the chromosomes
Anaphase I: spindle fibers pull the homologous chromosomes towards opposite ends of the cell
Telophase I & Cytokinesis: nuclear membrane forms and the cell separates into two individual cells

22. Meiosis II No DNA replication
The two cells produced by Meiosis I now enter a second meiotic division
Prophase II: two haploid(N) daughter cells
Metaphase II: chromosomes line up
Anaphase II: sister chromatids separate
Telophase II & Cytokinesis: results in 4 haploid cells

23. Gamete Formation Spermatogenesis Oogenesis
Females undergo meiosis before birth and it immediately stops when you’re born. Hormone levels during puberty cause menstruation with the release of one egg per month for about 25 years.
Males do not begin meiosis until puberty.

24. “DNA Detectives Get Teeth to Talk”
Homework
“DNA Detectives Get Teeth to Talk”
What is the main idea of article?
How does it relate to our standard?
How does it relate to what you already know about genetics?
Write vocabulary that you don’t understand.