How many stages of cell division do you see in this image? Genetics Unit: Mitosis

) Cell Cycle Mitosis will be our main focus. First, we will look at Interphase…

Interphase ) Longest stage of cell division (90% of cell cycle) Nucleus is visible Cell is growing and DNA is being replicated.

Interphase: 3 Phases ) 1.G 1 : Cell is Growing 2.S: DNA is Synthesized (DNA Replication) 3.G 2 : Organelles duplicate in preparation for division Most of these cells are in Interphase

Limits to Cell Growth Total Surface Area: Height x Width x Number of sides x Number of boxes Total Volume: Height x Width x Length x Number of boxes Surface-to-volume ratio: Surface Area/ Total Volume

What’s the problem with a low surface-to-volume ratio? 1.Materials have trouble entering and leaving the cell. 2.The cell can’t make enough mRNA to meet the demands of the cell. O2O2 O2O2

What are the key roles of cell division? 1.Cell division functions in: a.Reproduction for some organisms b.Growth of an organism from a fertilized egg c.Repair of cells that die from normal wear and tear or accidents 2.Cell division distributes identical sets of chromosomes to daughter cells

Key Vocabulary DNA molecules are packaged into. –Human (body cells) have 46 –Human (sperm or eggs) have 23 Chromosomes are made of a material called. chromosomes somatic cells gametes chromosomes. chromatin

Key Vocabulary Chromatin is composed of and. It is supercoiled around proteins, called. Together the DNA and histone molecules form bead-like structures called DNA proteins histones nucleosomes

Key Vocabulary sister chromatids centromere The chromosome is duplicated. Each duplicated chromosome consists of two. These are connected by a.

Mitosis (M Phase) The M Phase consists of: Mitosis and Cytokinesis Four Stages of Mitosis: P rophase M etaphase A naphase T elophase

Late Interphase: G 2 Centrosomes (with centriole pairs) Preparing for Division 1.Nuclear membrane still visible Nucleolus 2.Chromatin has been replicated

Late Interphase: G 2 Preparing for Division 4.Chromosome consisting of two sister chromatids Centromere Early Spindle Apparatus Prophase 3.Nuclear membrane disappears

Metaphase 5. Chromosomes line up at an imaginary line between the centrosomes at opposite ends of the cell. 6.The spindle attaches to the centromeres.

Anaphase 7.Spindles pull the “daughter” chromosomes appart

Telophase & Cytokinesis Telophase 8.Two nuclei become visible In animal cells, a Cleavage Furrow is visible In plant cells, a cell plate is now visible Cytokinesis 9.The cytoplasm and organelles divide.

What’s the end product? Two identical daughter cells ready to start the cycle again… or not. Some cells (like your nerve and muscle cells) do not undergo division. For those that do (your skin and the lining of your intestinal tract) how would you know how quickly division takes place?