Cell Growth and Reproduction (Chapter 8.2)

Mitosis notes outline Why cells divide repair/ replace diffusion too slow Cell division begins___ ends___ chromatin vs. chromosomes (picture and parts) III. Cell cycle 1. interphase 2. mitosis prophase metaphase anaphase telophase 3. cytokinesis animal vs plant end result=

Why do cells need to divide? To repair and replace old cells! Cell theory states that all cells come from preexisting cells!

Why don’t cells just keep growing? Diffusion is too slow over long distances If cells were too large, it would take too long to obtain nutrients and remove wastes

Section 8.2 Summary – pages 201 - 210 Cell Division The process when 2 cells are produced from one cell Begins with one parent cell Results in 2 daughter cells identical to the parent cell Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Where is genetic material found in a cell? DNA is found in the nucleus Chromatin (jumbled strands of DNA) Chromosomes—when chromatin condenses during cell division, looks like an X Human body cells have 46 chromosomes. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 The structure of eukaryotic chromosomes Centromere Sister chromatids Supercoil within chromosome Chromosome Continued coiling within supercoil Histone H1 Nucleosome DNA Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Cell Reproduction Cell cycle—sequence of growth and division of a cell, divided into 3 main periods Interphase >75% Mitosis Cytokinesis Mitosis Interphase Cytokinesis Section 8.2 Summary – pages 201 - 210

Centrioles replicate; cell prepares for division Interphase G1: cell grows, metabolism occurs S: DNA replication (make exact copy) G2: more growth, organelles made, prepares for division DNA synthesis and replication Rapid growth and metabolic activity Centrioles replicate; cell prepares for division

Section 8.2 Summary – pages 201 - 210 Mitosis Process of cell division where 2 identical daughter cells are formed Divided into 4 phases: prophase, metaphase, anaphase, telophase Mitosis Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 1. Prophase: longest phase of mitosis Chromatin--coils into visible chromosomes Sister chromatids—doubled strands of DNA held together by a centromere Sister chromatids Centromere Chromosome Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Prophase Nuclear envelope—begins to disappear and nucleolus disintegrates Spindle fibers—form from each end of cell Spindle fibers Disappearing nuclear envelope Doubled chromosome Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 2. Metaphase: shortest phase of mitosis Doubled chromosomes are lined up along the equator (midline) of the cell Centromere Sister chromatids Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 3. Anaphase Centromeres split Chromosomes are pulled apart and separated by spindle fibers Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 4. Telophase Cell membrane begins to split cell in 2 Opposite of prophase: spindle disappears and nucleus reappears Nuclear envelope reappears Two daughter cells are formed Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Cytokinesis Division of the cytoplasm In animal cells— 2 cells are separated by membrane “pinching in” between them Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Cytokinesis Division of the cytoplasm In plant cells— 2 cells are separated by a cell plate that forms in between them Section 8.2 Summary – pages 201 - 210

Mitosis Prophase Metaphase Anaphase Telophase

Mitosis Prophase Metaphase Anaphase Telophase

Mitosis results in…. 2 new daughter cells IDENTICAL to the parent cells Remember: cells→tissue→organ→organ system

Section 8.2 Summary – pages 201 - 210 Results of Mitosis Click image to view movie. Section 8.2 Summary – pages 201 - 210