1. Ch. 10 : Cell Division and Growth

2. 10-1: Cell Reproduction Why do cells divide? How is DNA packaged in the nucleus? How do cells prepare for division? Cells are busy making more cells. The reproduction of cells allows you to grow and heal.

3. Cell reproduce to : Control cell size (many smaller cells are more efficient than one large cell)  Surface area to volume ratio for supplies, proteins and control by nucleus Make new cells  Growth in multicellular organisms  Development  replace Repair  Wounds Reproduce  If you are single celled

4. Chromosomes DNA is a long thin, coiled molecule. DNA is a chemical DNA’s job is to store and transfer information DNA is made of nucleotides, each human cell has DNA totaling 6 billion nucleotide pairs!

5. Chromosome structure DNA in a eukaryotic nucleus is thin and uncoiled – it is called chromatin. Chromatin is available for the cell to use as information When the eukaryotic cell divides the DNA must be copied, packaged and move to new nuclei. The packaged format is called chromatids and chromosomes. This is only for cell division.

6. Chromosome structure Prokaryotes  One chromosome  Circular  No nucleus  plasmids Eukaryotes  Many (humans have 23 pairs or 46)  Linear  Inside nuclear membrane  DNA is copied into RNA

7. DNA DNA is a long thin chemical chain, made of nucleotides, in the form of a double helix. DNA wrapped around protein is called chromatin and chromatin coiled into visible threads is a chromosome. After DNA copies each part is called a chromatid and they travel together connected at a structure called a centromere.

8. Chromosome numbers Normal humans have 23 pairs of chromosomes ( 46 total). 22 pairs are autosomes, regular chromosomes The 23 rd pair is called the sex chromosomes and determines your gender  X X means a female  X Y means a male

9. Preparing for division Prokaryotes – “Binary Fission”  Copy one chromosome  Membrane indents  Wall forms  2 gentically identical cells Eukaryotes – “Mitosis”  S of interphase (Interphase = G1, S and G2)  All chromosomes are copied  Nuclear membrane dissolves  Other organelles and structures are copied and formed  Then enters MITOSIS which is nuclear division

10. Vocabulary Homologous chromosomes  are the two copies of each autosome, same size and same shape and same genes in the same locations. Karyotypes  pictures of your chromosomes from a microscope (WBC) and arranged in order from longest to shortest.

11. Karyotype

12. More vocabulary Diploid cells/ diploid number  cells that contain both chromosomes from each homologous pair. ( 23 pairs, or 46 total, in humans). All of our cells that are NOT egg or sperm. Haploid cells/ haploid number  cells that only contain one from each pair for 23 total chromosomes. These cells would include eggs, sperm and cells like pollen and spores in plants and fungi. They are reproductive cells, as opposed to body (somatic) cells.

13. 10-2: Mitosis What are the phases of the eukaryotic cell cycle? What are the stages of mitosis? How does cytokinesis occur? The events of the cycle ensure that new cells will be just like the old cell.

14. 10-2: Eukaryotic Cell Cycle Binary fission  the division of prokaryotic cells (bacteria) into two new cells. Mitosis  cell division in eukaryotic cells that results in two new, identical, diploid cells. (skin cell makes new skin cells) Meiosis  division in specialized eukaryotic cells that reduces the number of chromosomes to haploid - creating reproductive cells.

15. Mitosis Review Steps of Mitosis Interphase: grow, copy DNA Prophase: chromosomes and structures visible Pro-metaphase: spindle complete Metaphase: chromosomes aligned at equator Anaphase: chromosomes and copies separate and move Telophase: new nuclei form Cytokinesis: cytoplasm and organelles are divided. Cell plate is formed in plant cells xxxx

16. Mitosis occurring in root cells of onion

17. 10-3: Regulation Environmental and genetic clues Chemicals Contact Inhibition Check points

18. 8-3 MEIOSIS “reduction division” Produces reproductive cells, that are haploid and are generically called gametes Cells still do Interphase, one and only one time to copy the chromosomes Then they divide twice, producing four cells.... This reduces the number of chromosomes – ½ from each parent

19. Meiosis terminology Synapsis  pairing of homologous chromosomes that only occurs during meiosis. Chromsome #1 and its copy chromatid and the OTHER chromosome #1 and its copy chromosome pair up. Creating a group of four Tetrad  group of four. “Pairs of pairs” of chromosomes. Crossing over  some times adjacent pieces of chromsomes break and re-align with another part of the tetrad.

20. Terminology continued Genetic recombination  as a result of crossing over eggs and sperm can give offspring different combinations than that of the parent.  Grandma has brown hair and blue eyes  Grandpa has blonde hair and brown eyes  Mom has brown hair and brown eyes but could give the child an egg with the information for  Child = blonde hair and brown eyes

21. End of vocabulary Independent Assortment  each chromsome pair goes to the gametes without the influence of the other chromosomes – can get grandmas info. for # 4 and grandpas info for # 17. Spermatogenesis – process where specialized cells create sperm Oogenesis – process where specialized cells make ova (eggs) Asexual reproduction – offspring are produced by one parent through mitosis Sexual reproduction – offspring are produced by union of egg and sperm. Requires meiosis.