Ch 8.2 Cell Growth and Reproduction Learning about Asexual and Sexual reproduction of Cells

Why do Cells Grow? Larger the cell  not enough DNA to “tell” it what to do Larger the cell  not enough DNA to “tell” it what to do Larger the cell  more difficult to exchange materials (ex. Waste) Larger the cell  more difficult to exchange materials (ex. Waste)

Surface area to volume ratio: The volume of a cell increases faster than its surface area. Surface area to volume ratio: The volume of a cell increases faster than its surface area. So for a cell to work  it must divide and make more cells So for a cell to work  it must divide and make more cells

Types Of Reproduction 1. Asexual Reproduction: production of offspring by a single parent ex. Bacteria reproduce by splitting in half (after making a copy of Genetic Info) in a process called Binary Fission ex. Eukaryotic Cells: make new cells through the Cell Cycle

Cell Cycle/ Cell Division Process by which a cell divides into 2 new “daughter” cells  Identical!! Process by which a cell divides into 2 new “daughter” cells  Identical!! Type of Asexual Reproduction Type of Asexual Reproduction

Chromosomes Made up of DNA Made up of DNA Visible during cell division Visible during cell division : copy of DNA or chromosome Chromatids: copy of DNA or chromosome

: area in the middle where chromosome are attached Centromeres: area in the middle where chromosome are attached

Cell Cycle Series of events a cell goes through as they grow and divide Series of events a cell goes through as they grow and divide In summary: In summary: 1. Cell grows and functions 2. Cell chromosomes copied 3. Cell prepares for nucleus to divide 4. Cell goes through mitosis 5. Cell divides into two cells that are identical to parent cell

Events of the Cell Cycle 1. Interphase: divided into 3 phases; G 1, S & G 2 1. Interphase: divided into 3 phases; G 1, S & G 2 G 1: cells grow G 1: cells grow S phase: DNA replication S phase: DNA replication G 2: prepare for mitosis G 2: prepare for mitosis Interphase is the longest stage in the cell cycle! Interphase is the longest stage in the cell cycle!

2. Mitosis: The phase of the cell cycle when the cell begins division. Occurs when cell size is at a maximum. Occurs when cell size is at a maximum. Also called the M phase Also called the M phase

Four distinct phases, or stages. Four distinct phases, or stages. Occurs in every cell of your body. Occurs in every cell of your body. 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase

1. Prophase First and longest phase of mitosis First and longest phase of mitosis Chromosomes are visible Chromosomes are visible Centrioles (tiny support structures) move to each end of the nucleus. Centrioles (tiny support structures) move to each end of the nucleus. Spindle (fanlike microtubule) forms Spindle (fanlike microtubule) forms Nuclear envelope breaks down. Nuclear envelope breaks down.

2. Metaphase Chromosomes line up on center of cell Chromosomes line up on center of cell Each chromosome is connected to a spindle fiber at the centromere Each chromosome is connected to a spindle fiber at the centromere

3. Anaphase Sister chromatids separate into individual chromosomes and are moved apart Sister chromatids separate into individual chromosomes and are moved apart

4. Telophase Chromosomes opposite ends Chromosomes opposite ends Lose their shape Lose their shape 2 new nuclear envelopes form 2 new nuclear envelopes form

Cytokinesis Cytoplasm pinches in half Cytoplasm pinches in half Each daughter cell has an identical set of chromosomes Each daughter cell has an identical set of chromosomes

Name the Phase!

Animal Vs. Plant Cells Some variations happen in the cell cycle in plant cells: Some variations happen in the cell cycle in plant cells: Plant cells do not have centrioles Plant cells do not have centrioles Plant cells form a cell plate between daughter cells in cytokinesis Plant cells form a cell plate between daughter cells in cytokinesis

Cell Cycle Regulators Cyclins: protein which regulates the timing of the cell cycle Cyclins: protein which regulates the timing of the cell cycle Internal regulators Internal regulators External regulators External regulators

Uncontrolled cell growth Cancer: cancer cells do not respond to the signals that regulate the growth of most cells Cancer: cancer cells do not respond to the signals that regulate the growth of most cells What causes cancer? What causes cancer?