Cell Growth, Division, and Reproduction

Transcription

1 Cell Growth, Division, and Reproduction

2 Human Development: Mitosis and Meiosis

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4 Division of the Cell Before a cell grows too large, it divides into two new daughter cells in a process called cell division. Cell division reduces cell volume. It also results in an increased ratio of surface area to volume, for each daughter cell.

5 Asexual Reproduction Asexual reproduction is reproduction that involves a single parent producing an offspring. The offspring produced are, in most cases, genetically identical to the single cell that produced them.

6 Sexual Reproduction In sexual reproduction, offspring are produced by the fusion of two sex cells one from each of two parents. These fuse into a single cell before the offspring can grow.the offspring produced inherit some genetic information from both parents.

7 The Process of Cell Division

8 Terms to Know 1. Cell Cycle 2. G1 Phase 3. S Phase 4. G2 Phase 5. M Phase 6. Mitosis 7. Cytokinesis 8. Prophase 9. Metaphase 10.Anaphase 11.Telophase 12.Chromatids 13.Centrioles 14.Cytokinesis

9 Chromosomes structures in the nucleus that contain genetic material.

10 Prokaryotic Chromosomes Prokaryotic cells lack nuclei. Instead, their DNA molecules are found in the cytoplasm. Most prokaryotes contain a single, circular DNA molecule, or chromosome, that contains most of the cell s genetic information.

11 Eukaryotic Chromosomes In eukaryotic cells, chromosomes are located in the nucleus, and are made up of chromatin. Chromatin is composed of DNA and histone proteins.

12 The nucleosomes interact with one another to form coils and supercoils that make up chromosomes. Level of organization from big to small Chromosomes Nucleosomes Histones DNA

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15 The Prokaryotic Cell Cycle Most prokaryotic cells begin to replicate, or copy, their DNA once they have grown to a certain size. When DNA replication is complete, the cells divide through a process known as binary fission. Binary fission is a form of asexual reproduction during which two genetically identical cells are produced.

16 The Eukaryotic Cell Cycle

17 The Eukaryotic Cell Cycle The eukaryotic cell cycle consists of four phases: G1, S, G2, and M. Interphase is a period of growth that includes G1, S, and G2 phases. M phase or Mitosis - is cell division.

18 G 1 Phase: Cell Growth In the G 1 phase, cells increase in size and synthesize new proteins and organelles.

19 S Phase: DNA Replication In the S (or synthesis) phase, new DNA is synthesized when the chromosomes are replicated.

20 G 2 Phase: Preparing for Cell Division In the G 2 phase, many of the organelles and molecules required for cell division are produced.

21 M Phase: Cell Division In eukaryotes, cell division occurs in two stages: mitosis and cytokinesis. Mitosis is the division of the cell nucleus. Cytokinesis is the division of the cytoplasm.

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23 Mitosis

24 Mitosis Prophase

25 Mitosis Metaphase

26 Mitosis Anaphase

27 Mitosis Telophase

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29 Important Cell Structures Involved in Mitosis Chromatid each strand of a duplicated chromosome Centromere the area where each pair of chromatids is joined Centrioles tiny structures located in the cytoplasm of animal cells that help organize the spindle Spindle a fanlike microtubule structure that helps separate the chromatids

30 Prophase During prophase, the first phase of mitosis, the duplicated chromosome condenses. The centrioles move to opposite sides. The spindle forms and DNA attaches at a point called the centromere. The nuclear envelope breaks down.

31 Metaphase During metaphase, the second phase of mitosis, the centromeres of the duplicated chromosomes line up across the center of the cell. The spindle fibers connect the centromere of each chromosome to the two poles of the spindle.

32 Anaphase During anaphase, the third phase of mitosis, the centromeres are pulled apart and the chromatids separate to become individual chromosomes.

33 Metaphase Anaphase

34 Telophase During telophase, the fourth and final phase of mitosis, the chromosomes spread out. A nuclear envelope re-forms. Cytokinesis completes the process of cell division it splits one cell into two.

35 The Stages of the Cell Cycle

36 Cell Specilization The process by which cells become specialized is known as differentiation. Stem cells are unspecialized cells from which differentiated cells develop. There are two types of stem cells: embryonic and adult stem cells.

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38 Video on cell processes Crash Course on Mitosis: 3D Animation of Mitosis: