Translation

Translation

Translation

Protein Synthesis Interactions Animation You must be connected to the internet to run this animation.

Somatic Cell Division - Mitosis The cell cycle is a sequence of events in which a body cell duplicates its contents and divides in two Human somatic cells contain 23 pairs of chromosomes (total = 46) The two chromosomes that make up each pair are called homologous chromosomes (homologs) Somatic cells contain two sets of chromosomes and are called diploid cells

Cell Division Interphase - the cell is not dividing - The cell replicates its DNA - Consists of three phases, G1, S, and G2, replication of DNA occurs in the S phase Mitotic phase - consists of a nuclear division (mitosis) and a cytoplasmic division (cytokinesis) to form two identical cells

The Cell Cycle

DNA Replication

Nuclear Division: Mitosis Prophase - the chromatin fibers change into chromosomes. Metaphase - microtubules align the centromeres of the chromatid pairs at the metaphase plate. Anaphase - the chromatid pairs split at the centromere and move to opposite poles of the cell; the chromatids are now called chromosomes. Telophase - two identical nuclei are formed around the identical sets of chromosomes now in their chromatin form.

Cytoplasmic Division: Cytokinesis Division of a cell’s cytoplasm to form two identical cells Usually begins in late anaphase The plasma membrane constricts at its middle, forming a cleavage furrow The cell eventually splits into two daughter cells. Interphase begins when cytokinesis is complete .

Mitosis 1 Early Late (d) ANAPHASE Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol (a) INTERPHASE Centrioles Centrosome: Cleavage furrow (e) TELOPHASE (c) METAPHASE 2 3 4 5 Cleavage furrow (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore Metaphase plate Chromosome all at 700x LM (two chromatids joined at centromere Centromere 1 Early Late (d) ANAPHASE Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol (a) INTERPHASE Centrioles Centrosome: (f) IDENTICAL CELLS IN INTERPHASE Cleavage furrow (e) TELOPHASE (c) METAPHASE Cleavage furrow 2 3 4 5 6 (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore Metaphase plate Chromosome all at 700x LM Centromere (two chromatids joined at centromere 1 Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol (a) INTERPHASE Centrioles Centrosome: all at 700x LM 1 Early Late (d) ANAPHASE Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol Chromosome (a) INTERPHASE Centrioles Centrosome: (c) METAPHASE 2 3 4 Cleavage furrow (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore Metaphase plate all at 700x LM (two chromatids joined at centromere Centromere 1 Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol Metaphase plate (a) INTERPHASE Centrioles Centrosome: (c) METAPHASE 2 3 Late Early (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore all at 700x LM Chromosome (two chromatids joined at centromere Centromere 1 Late Early Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol Chromosome (two chromatids joined at centromere (a) INTERPHASE (b) PROPHASE Centrioles Centrosome: Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore 2 all at 700x LM Centromere Mitosis

Mitosis

Mitosis

Mitosis

Mitosis

Mitosis

Mitosis

Reproductive Cell Division During sexual reproduction, each new organism is the result of the union of two gametes (fertilization), one from each parent. Meiosis - reproductive cell division that occurs in the gonads (ovaries and testes) that produces gametes with half the number of chromosomes. Haploid cells - gametes contain a single set of 23 chromosomes. Fertilization restores the diploid number of chromosomes (46).

Reproductive Cell Division Meiosis occurs in two successive stages: meiosis I and meiosis II . Each of these two stages has 4 phases: prophase, metaphase, anaphase, and telophase. Summary - Meiosis I begins with a diploid cell and ends with two cells having the haploid number of chromosomes; in Meiosis II, each of the two haploid cells divides, and the net result is four haploid gametes that are genetically different from the original diploid starting cell.

Meiosis and Cytokinesis

Comparison of Mitosis and Meiosis

Cell Division Interactions Animation The Cell Cycle and Division Processes Interactions Animation You must be connected to the internet to run this animation.

Cellular Diversity The average adult has nearly 100 trillion cells. There are about 200 different types of cells. Cells come in a variety of shapes and sizes. Cellular diversity permits organization of cells into more complex tissues and organs.

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