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Cell Reproduction
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Chromosomes: made of DNA
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DNA: stores all genetic information -genes: a hereditary unit of DNA -4 bases: -Adenine -Thymine -Guanine -cytosine
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DNA in the Cell 1.Chromosome 2.Supercoil 3.Subcoil 4.One coil 5.DNA with histine protein 6.DNA
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Chromosome Anatomy
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Chromosome Types 1.Sex Chromosomes: determines the sex of an organism -XY: male -XX: female 2.Autosomes: All other chromosomes of an organism
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Chromosome Duplication
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Homologous Chromosomes: two copies of each autosome – same size, shape, and genes
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Karyotype: photomicrograph of chromosomes Humans have 22 pairs of autosomes and 1 pair of sex chromosomes
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Diploid Cells (2n): cells with both sets of chromosomes (both homologous pairs) 46 chromosomes/23 pairs in humans
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Haploid cells (1n): cells with one set of chromosomes
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“C” words of Cytology 1. Chromosome: condensed genetic material 2.Chromatid: one of two identical copies of DNA 3.Centromere: region that joins the chromatids
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“C” words of Cytology 4.Centrioles: cylindrical structures that assist in cell division 5.Centrosome: dark regions in the cytoplasm that create spindle fibers
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Cell Division: all cells come from pre- existing cells
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2 Types of Division
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1. Mitosis: cell division which produces 2 diploid, identical cells
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2. Meiosis: cell division which produces 4 haploid cells
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Cell Life Cycle 1.Interphase: G1, S, and G2 G = growth S = Synthesis 2.M phase: mitosis – nuclear division 3.Cytokinesis: cytoplasm division
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Interphase 1. Interphase: DNA not visible -nucleus still intact
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Phases of Mitosis 2.Prophase: chromosomes become visible -nucleus disintegrates
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Phases of Mitosis 3.Metaphase: chromosomes connect at the centromere to spindle fibers -line up at the equatorial plate
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Phases of Mitosis 4.Anaphase: spindle fibers recede -pull chromosomes apart -chromosomes retreat to opposite ends
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Phases of Mitosis 5.Telophase: nucleus reforms Cytokinesis splitting the cell -2 daughter cells are formed
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Meiosis: cell division which produces 4 haploid cells
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Haploid: a cell with half the number of chromosomes (1n)
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Fertilization: the fusion of two gametes (sperm/eggs)
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Review terms:
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Karyotype
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Homologous Chromosomes: identical chromosomes – one from each parent
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Chromatid: one of two identical copies of the same DNA
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Mitosis vs. Meiosis Mitosis -Produces two offspring cells of 2n -One cell division cycle -produces body cells -no chromosomes cross over Meiosis -produces four offspring cells of 1n -two cell division cycles (meiosis I & 2) -produces gametes -chromosomes cross over
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8 Stages of Meiosis Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Meiosis I Meiosis II
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Prophase I -Chromatids form -Homologous chromatids pair up to form tetrads
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Metaphase I -tetrads line up at equatorial plate -Crossing over: breaking off of arms of chromatids and switching places on another homologous chromosome
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Anaphase I -tetrads are pulled apart
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Telophase I -cytokinesis occurs
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Prophase II
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Metphase II
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Anaphase II
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Telophase II
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Spermatogenesis: meiosis that produces sperm Produces 4 fertile cells; in humans @ 400 billion
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Oogenesis: meiosis that produces egg cells Produces 1 fertile cell; about 400 in a lifetime
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Types of Reproduction 1.Sexual reproduction: offspring are the result of combination of parental genetics 2.Asexual reproduction: no exchange of genetic information – genetically identical to parent
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Nature protects the female
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Cellular Disorders
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Cancer: a mitotic disorder
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Characteristics: 1.Abnormal rates of cell division; uncontrolled 2.Produces malfunctioning cells 3.Kills the organism 4.Lack Density Dependent Inhibition (DDI)
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Density Dependent Inhibition (DDI) Ability of a cell to “sense” space – ability to stop growth in a restricted space
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Density Dependent Inhibition (DDI) Lack of DDI – cells continue to divide – causes tumors
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Types of Tumors 1.Benign: cancer cells remain at the original site 2.Malignant: cancer cells become aggressive and spread throughout the body
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Metastasis: movement of cancer through the blood/lymph to other organs
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Causes: carcinogens and contributing factors
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-smoking
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-radiation
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-virus (HPV)
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-genetic makeup
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Treatments
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-surgical removal
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-radiation treatment
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-chemotherapy: taxol, vincristine, vinblastine
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Cellular Differentiation -begins following fertilization -process by which generic cells gain specific functions -mitosis process
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Stem Cells: undifferentiated cells that can become any type of cell Stem Cells Skin Cells Neuron (nerves) Bone Cell Muscle Cells Cardiac Muscle
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