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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
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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. )
Most of these cells are in Interphase Interphase:3 Phases • G1: Cell is Growing • S: DNA is Synthesized (DNA Replication) • G2: Organelles duplicate in preparation for division )
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 6 150 750 1 125 125 6 1.2 6
What’s the problem with a low surface-to-volume ratio? • Materials have trouble entering and leaving the cell. • The cell can’t make enough mRNA to meet the demands of the cell. O2 O2
What are the key roles of cell division? • Cell division functions in: • Reproduction for some organisms • Growth of an organism from a fertilized egg • Repair of cells that die from normal wear and tear or accidents • 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 chromosomes. 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 • The chromosome is duplicated. • Each duplicated chromosome consists of two . • These are connected by a . sister chromatids centromere
Mitosis (M Phase) The M Phase consists of: • Mitosis and Cytokinesis Four Stages of Mitosis: • Prophase • Metaphase • Anaphase • Telophase
Preparing for Division Late Interphase: G2 Centrosomes (with centriole pairs) 1.Nuclear membrane still visible Nucleolus 2.Chromatin has been replicated
Preparing for Division Late Interphase: G2 Prophase Centromere Early Spindle Apparatus 3.Nuclear membrane disappears 4.Chromosome consisting of two sister chromatids
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 Telophase & Cytokinesis 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?