Lesson 12 - The Cell Cycle, DNA Replication, and Mitosis PDF

The Cell Cycle, DNA Replication, and Mitosis Lesson 12 TEACHER COPY  The Cell Cycle ⚫ Cell cycle – describes the stages in a single cell’s life. ⚫ Interphase is the longest phase. ⚫ G1 stage – cell grows ⚫ S stage – DNA replicated....

The Cell Cycle, DNA Replication, and Mitosis Lesson 12 TEACHER COPY  The Cell Cycle ⚫ Cell cycle – describes the stages in a single cell’s life. ⚫ Interphase is the longest phase. ⚫ G1 stage – cell grows ⚫ S stage – DNA replicated. Genetic material in a cell doubles. ⚫ G2 stage – cell prepares to divide ⚫ Mitosis – nuclear division that produces an exact replica of the nucleus and all of its chromosomes. ⚫ Cytokinesis – final stage of cell cycle during which cytoplasm divides into two. Every species has a characteristic number of chromosomes in its body cells. For humans, the number is 46. Egg and sperm cells, or gametes, have 23 chromosomes each. Can mitosis produce gametes? Explain. Mitosis cannot produce gametes because it keeps the number of chromosomes in the daughter cells the same as in the parent cell.  Chromosome Number ⚫ Every species has a characteristic chromosome number, which is the number of chromosomes in its body cells – called the diploid number. ⚫ Cell wants to make two identical copies of itself, must first duplicate its nucleus. ⚫ If parent cell has 46 chromosomes, each daughter cell must have 46. ⚫ Requires DNA to make a copy of itself – DNA replication – occurs during S phase of Interphase. ⚫ Each chromosome – two DNA “arms” with a centromere in the center. ⚫ Replication produces an identical copy of each “arm,” but the copies are still joined at the centromere – called sister chromatids – remain joined until mitosis. ⚫ Chromosome Number  DNA Replication ⚫ DNA replication is carried out by enzymes. ⚫ Enzymes are often named for their function – DNA polymerase helps to assemble a DNA polymer. ⚫ DNA helicase – binds to a site on the double stranded DNA and begins to separate the two strands. ⚫ DNA polymerase – moves along each strand, pairing free nucleotides to the nucleotides on the strand. DNA Replication ⚫ Complementary base pairing rules: ⚫ Adenine (A) with Thymine (T) ⚫ Cytosine (C) with Guanine (G) ⚫ Ensures that new strands are identical to old strands. ⚫ Original DNA serves as template for new strand. ⚫ Semiconservative replication – each “new” double strand consists of one original strand and one newly assembled strand.  Mitosis ⚫ DNA replicated – S phase ⚫ Proteins synthesized – G2 phase ⚫ Now the cell is ready for MITOSIS!!! ⚫ Mitosis – process of duplicating the nucleus ⚫ Four phases: Prophase, Metaphase, Anaphase, Telophase Prophase ⚫ Nucleus disappears ⚫ Chromosomes condense from chromatin ⚫ Centrioles begin to move toward the poles Metaphase ⚫ Centrioles produce spindle fibers. ⚫ Spindle fibers attach to the centromeres on the sister chromatids. ⚫ Chromatids line up in the center of the cell Anaphase ⚫ Spindles shorten – pull sister chromatids apart ⚫ Chromatids from each pair move toward opposite poles. Telophase ⚫ New nuclear membranes form around the newly separated chromosomes. ⚫ Chromosomes unwind, becoming longer and thinner. Cytokinesis ⚫ Cytokinesis – process in which the cytoplasm, organelles, and plasma membrane of a cell divide to form two daughter cells. ⚫ Plant cells, which have cell walls, must form a cell plate between the two nuclei.  Telophase Prophase Anaphase Metaphase ⚫ Explain how mitosis ensures that daughter cells have the correct number and types of chromosomes. ⚫ At the beginning of mitosis, each chromosome has replicated its DNA. The two identical sister chromatids are joined at the centromere. During metaphase, spindle fibers attach to the centromeres. The fibers are anchored to centrioles at opposite ends of the cell. When the chromatids separate, each one is joined to one centromere. The chromatids are pulled to opposite sides of the cell, and each one becomes part of one new nucleus. In this way, mitosis ensures that each nucleus contains one copy of each chromosome.  Which statement best describes the stage of mitosis shown in the illustration? A. The cell is in telophase because the chromosomes are unpaired. B. The cell is in anaphase because the chromosomes have replicated. C. The cell is in prophase because the chromosomes have condensed. D. The cell is in metaphase because the chromosomes are aligned in the center.  Which is one difference between a parent cell and a daughter cell that results from mitosis? A. The daughter cell has sister chromatids, while the parent cell does not. B. The daughter cell has half the number of chromosomes as the parent cell. C. The daughter cell has paired chromosomes, while the parent cell does not. D. The daughter cell has half the amount of genetic material as the parent cell.  Which sentence lists the events in the cell cycle in correct order, from earlier to later? A. The chromosomes replicate; the nuclear membrane dissolves B. The sister chromatids are separated; the chromosomes condense C. The nuclear membrane reforms; the chromosomes align in the middle of the cell D. The chromosomes become longer and thinner; spindle fibers attach to the centromeres  1. What is the cell cycle? 2. Draw and label a pie chart of the cell cycle. 3. What is the diploid number? What is the human diploid number? 4. Draw a picture of a chromosome. Label the centromere and the sister chromatids. 5. What is DNA helicase? 6. What is DNA polymerase? 7. What is semiconservative replication? 8. What are the four phases of mitosis? 9. Draw and label mitosis, including interphase the ending number of cells. 10. What is cytokinesis? 11. What special structure is formed during cytokinesis in plant cells? The Cell Cycle, DNA Replication, and Mitosis Lesson 12 STUDENT COPY  The Cell Cycle ⚫ ________________– describes the stages in a single cell’s life. ⚫ ______________ is the longest phase. ⚫ _______________– cell grows ⚫ _______________– DNA replicated. Genetic material in a cell doubles. ⚫ _______________– cell prepares to divide ⚫ _____________– nuclear division that produces an exact replica of the nucleus and all of its chromosomes. ⚫ _____________– final stage of cell cycle during which cytoplasm divides into two. Every species has a characteristic number of chromosomes in its body cells. For humans, the number is 46. Egg and sperm cells, or gametes, have 23 chromosomes each. Can mitosis produce gametes? Explain. _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ ________________________________.  Chromosome Number ⚫ Every species has a characteristic chromosome number, which is the number of chromosomes in its body cells – called the _________________ number. ⚫ Cell wants to make two identical copies of itself, must first duplicate its _________________. ⚫ If parent cell has _____ chromosomes, each daughter cell must have ________. ⚫ Requires DNA to make a copy of itself – DNA replication – occurs during S phase of Interphase. ⚫ Each chromosome – two DNA “arms” with a __________________in the center. ⚫ Replication produces an identical copy of each “arm,” but the copies are still joined at the centromere – called _________________________– remain joined until mitosis. ⚫ Chromosome Number DNA Replication ⚫ DNA replication is carried out by __________________. ⚫ Enzymes are often named for their function – DNA polymerase helps to assemble a DNA polymer. ⚫ ______________________– binds to a site on the double stranded DNA and begins to separate the two strands. ⚫ ______________________– moves along each strand, pairing free nucleotides to the nucleotides on the strand. DNA Replication ⚫ Complementary base pairing rules: ⚫ __________________ ⚫ __________________ ⚫ Ensures that new strands are identical to old strands. ⚫ Original DNA serves as template for new strand. ⚫ _________________– each “new” double strand consists of one original strand and one newly assembled strand.  Mitosis 1. DNA replicated – _________________ 2. Proteins synthesized – _________________ 3. Now the cell is ready for _______________!!! ⚫ Mitosis – process of duplicating the nucleus ⚫ Four phases: __________________ __________________ __________________ __________________ Prophase ⚫ Nucleus ___________________ ⚫ Chromosomes condense from chromatin ⚫ _____________begin to move toward the poles Metaphase ⚫ Centrioles produce ____________________. ⚫ Spindle fibers attach to the ________________on the sister chromatids. ⚫ Chromatids line up in the center of the cell Anaphase ⚫ Spindles shorten – pull sister chromatids _____ ⚫ Chromatids from each pair move toward opposite poles. Telophase ⚫ New _____________________ form around the newly separated chromosomes. ⚫ Chromosomes unwind, becoming longer and thinner. Cytokinesis ⚫ ____________________ – process in which the cytoplasm, organelles, and plasma membrane of a cell divide to form two daughter cells. ⚫ Plant cells, which have cell walls, must form a _____________ between the two nuclei.  ____________ ________________ _______________ _______________ Explain how mitosis ensures that daughter cells have the correct number and types of chromosomes. ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________  Which statement best describes the stage of mitosis shown in the illustration? A. The cell is in telophase because the chromosomes are unpaired. B. The cell is in anaphase because the chromosomes have replicated. C. The cell is in prophase because the chromosomes have condensed. D. The cell is in metaphase because the chromosomes are aligned in the center.  Which is one difference between a parent cell and a daughter cell that results from mitosis? A. The daughter cell has sister chromatids, while the parent cell does not. B. The daughter cell has half the number of chromosomes as the parent cell. C. The daughter cell has paired chromosomes, while the parent cell does not. D. The daughter cell has half the amount of genetic material as the parent cell.  Which sentence lists the events in the cell cycle in correct order, from earlier to later? A. The chromosomes replicate; the nuclear membrane dissolves B. The sister chromatids are separated; the chromosomes condense C. The nuclear membrane reforms; the chromosomes align in the middle of the cell D. The chromosomes become longer and thinner; spindle fibers attach to the centromeres