The Cell Cycle Chapter 9 pages 203 - 220 Created by C. Ippolito Updated March 2006 Created by C. Ippolito August 2004

Chapter 9 Sections 1 through 3 pages 203 - 208 The Life of a Cell Chapter 9 Sections 1 through 3 pages 203 - 208 Updated March 2006 Created by C. Ippolito August 2004

Cell Cycle Describes the “life” history of a cell How it grows How it carries out its functions How it produces replacement cells Updated March 2006 Created by C. Ippolito August 2004

Cell Cycle The cycle can focus on: the cell’s activities the activities of the nucleus of the cell Updated March 2006 Created by C. Ippolito August 2004

Cell Cycle Diagram Created by C. Ippolito Updated March 2006 August 2004

Life Cycle Focus Consists of FOUR (4) basic stages. G1 Stage - cell grows, forms organelles, carries out its function. (G0 - special stage of cells with special jobs that do not divide) S Stage - cell prepares for division by synthesis of materials (DNA replication) needed for new cells. G2 Stage - cell grows producing proteins needed for cell division. M Stage - cell divides to form 2 identical daughter cells. Updated March 2006 Created by C. Ippolito August 2004

Nuclear Cycle Focus Consists of FIVE (5) basic stages. Prophase - prepare nucleus and chromosomes for division. Metaphase - separate duplicate copies of chromosomes Anaphase - move of duplicate chromosomes to opposite sides of cell. Telophase - separate “old” cell into two smaller cells. Interphase - “inactivity” between divisions. Updated March 2006 Created by C. Ippolito August 2004

Mitosis Is the nuclear division in which duplicate chromosomes form two identical nuclei from one nucleus. Updated March 2006 Created by C. Ippolito August 2004

Control of Cell Cycle The accumulation of trigger proteins initiate cell division factors influencing the trigger proteins hormones cell size cell placement in tissue Updated March 2006 Created by C. Ippolito August 2004

Complete Check and Challenge on page 208 Homework Complete Check and Challenge on page 208 Updated March 2006 Created by C. Ippolito August 2004

Chapter 9 Sections 4 through 8 pages 208 - 214 DNA Replication Chapter 9 Sections 4 through 8 pages 208 - 214 Updated March 2006 Created by C. Ippolito August 2004

Deoxyribonucleic Acid (DNA) Forms hereditary material Made from DNA nucleotides Is a double helix Is found only in the nucleus Updated March 2006 Created by C. Ippolito August 2004

DNA Nucleotide Sugar is deoxyribose Phosphate group Four different nitrogen bases: Adenine pairs with Thymine Guanine pairs with Cytosine Updated March 2006 Created by C. Ippolito August 2004

Adenine Subunit Updated March 2006 Created by C. Ippolito August 2004

Guanine Subunit Updated March 2006 Created by C. Ippolito August 2004

Thymine Subunit Updated March 2006 Created by C. Ippolito August 2004

Cytosine Subunit Updated March 2006 Created by C. Ippolito August 2004

Base Pairing Remember in forming the double helix the bases A and T always combine the bases G and C always combine their shape insures this occurs Updated March 2006 Created by C. Ippolito August 2004

DNA Replication This concept of “base pairing” allows the DNA molecule to make exact copies of itself. Replication!!!!! Updated March 2006 Created by C. Ippolito August 2004

DNA Unzips a special enzyme opens the double helix This will allow exposed bases to be matched forming new “sides” The enzyme slowly proceeds down the middle of the DNA molecule It does this by breaking the weak hydrogen bonds between bases until the DNA molecule is completed opened Updated March 2006 Created by C. Ippolito August 2004

DNA Polymerase The enzyme positions them opposite the proper base to form new base pairs Nucleotides from cell storage area are brought in by enzymes Each strand is half new and half old DNA new hydrogen bonds form between the bases Resulting in two identical strands of DNA Updated March 2006 Created by C. Ippolito August 2004

Chapter 9 Sections 8 and 9 pages 214 - 219 Animal Mitosis Chapter 9 Sections 8 and 9 pages 214 - 219 Updated March 2006 Created by C. Ippolito August 2004

Animal Mitosis Interphase Prophase Metaphase Anaphase Telophase  nuclear membrane Two identical daughter cells  nucleolus centriole  chromatin Updated March 2006 Created by C. Ippolito August 2004

Early Prophase nuclear envelope and nucleoli begin to disappear chromatin condenses to form “doubled” chromosomes centrioles migrate to opposite poles spindle fibers form between the centrioles Updated March 2006 Created by C. Ippolito August 2004

Late Prophase nuclear membrane and nucleolus are gone centriole have formed asters at the poles spindle from each pole attaches to centromere of each chromosome Updated March 2006 Created by C. Ippolito August 2004

Animal Prophase cell membrane chromatin Created by C. Ippolito Updated March 2006 Created by C. Ippolito August 2004

Prophase nuclear envelope disappears spindle fibers form Chromatin condenses into chromosomes spindle fibers form centrioles migrate nucleolus disappears Updated March 2006 Created by C. Ippolito August 2004

Metaphase chromosomes line up at the equator of the cell centromeres break separating each chromosome into chromatids Updated March 2006 Created by C. Ippolito August 2004

Animal Metaphase centriole chromosome spindle fibers Updated March 2006 Created by C. Ippolito August 2004

Metaphase chromosome line up at equator centromeres split to separate daughter chromosomes chromosome line up at equator Updated March 2006 Created by C. Ippolito August 2004

Anaphase spindle guides chromatids to the poles cell membrane begins to pinch in to begin to form cleavage furrow Updated March 2006 Created by C. Ippolito August 2004

Animal Anaphase chromsome spindle centriole Created by C. Ippolito Updated March 2006 Created by C. Ippolito August 2004

Anaphase daughter chromosomes move to opposite poles Pinching forms a cleavage furrow to separate cytoplasm cell membrane starts to pinch in Updated March 2006 Created by C. Ippolito August 2004

Telophase cleavage furrow separates cytoplasm into 2 cells nuclear membrane and nucleoli reappear chromatids unwind to reform chromatin spindle fibers disappear centrioles reform centrosome Updated March 2006 Created by C. Ippolito August 2004

Animal Telophase chromatin cleavage furrow Created by C. Ippolito Updated March 2006 Created by C. Ippolito August 2004

Telophase Two identical daughter cells are formed Chromosomes unwind to reform chromatin spindle fibers disappear cleavage furrow continues to pinch in nuclear membrane & nucleolus reappear Updated March 2006 Created by C. Ippolito August 2004

No Centrioles, No Asters, and Cell Plate Plant Mitosis No Centrioles, No Asters, and Cell Plate Updated March 2006 Created by C. Ippolito August 2004

Prophase nuclear envelope and nucleoli begin to disappear chromatin condenses to form “doubled” chromosomes spindle fibers appear in the cytoplasm spindle attaches to centromeres of chromosomes Updated March 2006 Created by C. Ippolito August 2004

Prophase Updated March 2006 Created by C. Ippolito August 2004

Metaphase chromosomes line up at the equator of the cell centromeres break separating each chromosome into chromatids chromatids are also known as daughter chromosomes Updated March 2006 Created by C. Ippolito August 2004

Metaphase Updated March 2006 Created by C. Ippolito August 2004

Anaphase spindle contracts to guide chromatids to the poles Updated March 2006 Created by C. Ippolito August 2004

Telophase cell plate forms at equator to separate cytoplasm into 2 cells nuclear membrane and nucleoli reappear spindle fibers disappear chromatids unwind to reform chromatin Updated March 2006 Created by C. Ippolito August 2004

Telophase Updated March 2006 Created by C. Ippolito August 2004

Meiosis Special cell division to produce gametes with haploid (n) chromosome Number Updated March 2006 Created by C. Ippolito August 2004

Meiosis Is a process in which the original cell undergoes TWO divisions to produce FOUR cells with half of the original chromosome number. Main distinction from mitosis seen in metaphase I because chromsomes line up as pairs Updated March 2006 Created by C. Ippolito August 2004

Interphase Start with a 2n = 4 During interphase chromosomes double. Updated March 2006 Created by C. Ippolito August 2004

Prophase Synapsis occurs, the chromosomes “pair” to form tetrads - a group of 4 chromatids Tetrad  Updated March 2006 Created by C. Ippolito August 2004

Crossing Over During synapsis pieces of chromosomes can switch places Updated March 2006 Created by C. Ippolito August 2004

Metaphase The homologous pairs line up at equator Updated March 2006 Created by C. Ippolito August 2004

End of First Division Chromosome pairs are separated Updated March 2006 Created by C. Ippolito August 2004

Second Division Separates chromatids to form 4 cells with half the original number of chromosomes Updated March 2006 Created by C. Ippolito August 2004

Meiosis I First division of meiosis homologous pairs line up in process of synapsis crossing over may occur homologous pairs separate Updated March 2006 Created by C. Ippolito August 2004

Meiosis II Interkinesis - DNA not replicated Chromatids separate reduction division results in 4 haploid cells Updated March 2006 Created by C. Ippolito August 2004

Meiosis Vs Mitosis Created by C. Ippolito Updated March 2006 August 2004

Gametogenesis Specialized forms of meiosis to from sex cells. Spermatogenesis - meiosis to form male sex cells, sperm, occurs in testis. 4 sex cells formed from each primary sex cell Oogenesis - meiosis to form female sex cells, ova, occurs in ovaries. 1 large sex cell formed from each primary sex cell. Updated March 2006 Created by C. Ippolito August 2004

Spermatogenesis - produces 4 sperm cells. Spermiogenesis - spermatids change form Oogenesis - produces 1 ootid and 2 polar bodies Updated March 2006 Created by C. Ippolito August 2004