Cell Reproduction

Chromosomes: made of DNA

DNA: stores all genetic information -genes: a hereditary unit of DNA -4 bases: -Adenine -Thymine -Guanine -cytosine

Chromosome Anatomy

Chromosome Types 1.Sex Chromosomes: determines the sex of an organism -XY: male -XX: female 2.Autosomes: All other chromosomes of an organism

Chromosome Duplication

Homologous Chromosomes: two copies of each autosome – same size, shape, and genes

Karyotype: photomicrograph of chromosomes Humans have 22 pairs of autosomes and 1 pair of sex chromosomes

Diploid Cells (2n): cells with both sets of chromosomes (both homologous pairs) 46 chromosomes/23 pairs in humans

Haploid cells (1n): cells with one set of chromosomes

“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

“C” words of Cytology 4.Centrioles: cylindrical structures that assist in cell division 5.Centrosome: dark regions in the cytoplasm that create spindle fibers

Cell Division: all cells come from pre- existing cells

2 Types of Division

1. Mitosis: cell division which produces 2 diploid, identical cells

2. Meiosis: cell division which produces 4 haploid cells

Cell Life Cycle 1.Interphase: G1, S, and G2 G = growth S = Synthesis 2.M phase: mitosis – nuclear division 3.Cytokinesis: cytoplasm division

Interphase 1. Interphase: DNA not visible -nucleus still intact

Phases of Mitosis 2.Prophase: chromosomes become visible -nucleus disintegrates

Phases of Mitosis 3.Metaphase: chromosomes connect at the centromere to spindle fibers -line up at the equatorial plate

Phases of Mitosis 4.Anaphase: spindle fibers recede -pull chromosomes apart -chromosomes retreat to opposite ends

Phases of Mitosis 5.Telophase: nucleus reforms Cytokinesis splitting the cell -2 daughter cells are formed

Meiosis: cell division which produces 4 haploid cells

Haploid: a cell with half the number of chromosomes (1n)

Fertilization: the fusion of two gametes (sperm/eggs)

Review terms:

Homologous Chromosomes: same chromosomes – one from each parent

Chromatid: one of two identical copies of the same DNA

Meiosis -produces four offspring cells of 1n -two cell division cycles (meiosis I & 2) -produces gametes -chromosomes cross over

Mitosis Vs. Meiosis

8 Stages of Meiosis Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Meiosis I Meiosis II

Prophase I -Tetrads form

Metaphase I -Crossing over: exchange of genetic info between homologous chromosomes

Anaphase I -tetrads are pulled apart

Telophase I -cytokinesis occurs

Prophase II

Metphase II

Anaphase II

Telophase II

Spermatogenesis: meiosis that produces sperm Produces 4 fertile cells; in 400 billion

Oogenesis: meiosis that produces egg cells Produces 1 fertile cell; about 400 in a lifetime

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

Nature protects the female

Cellular Disorders

Cancer: a mitotic disorder

Characteristics: 1.Abnormal rates of cell division; uncontrolled 2.Produces malfunctioning cells 3.Kills the organism 4.Lack Density Dependent Inhibition (DDI)

Density Dependent Inhibition (DDI) Ability of a cell to “sense” space – ability to stop growth in a restricted space

Density Dependent Inhibition (DDI) Lack of DDI – cells continue to divide – causes tumors

Types of Tumors 1.Benign: cancer cells remain at the original site 2.Malignant: cancer cells become aggressive and spread throughout the body

Teratoma

Metastasis: movement of cancer through the blood/lymph to other organs

Causes: carcinogens and contributing factors

-smoking

-radiation

-virus (HPV)

-genetic makeup

Treatments

-surgical removal

-radiation treatment

-chemotherapy: taxol, vincristine, vinblastine

Cellular Differentiation -begins following fertilization -process by which generic cells gain specific functions -mitosis process

Stem Cells: undifferentiated cells that can become any type of cell Stem Cells Skin Cells Neuron (nerves) Bone Cell Muscle Cells Cardiac Muscle