Cell Reproduction Chromosomes made of DNA DNA stores

Cell Reproduction

Chromosomes: made of DNA

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

DNA in the Cell 1. 2. 3. 4. 5. Chromosome Supercoil Subcoil One coil DNA with histine protein 6. DNA

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

Haploid cells (1 n): 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 preexisting 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: G 1, S, and G 2 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 (1 n)

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

Review terms:

Karyotype

Homologous Chromosomes: identical chromosomes – one from each parent

Chromatid: one of two identical copies of the same DNA

Mitosis vs. Meiosis Mitosis Meiosis -Produces two offspring cells of 2 n -One cell division cycle -produces body cells -no chromosomes cross over -produces four offspring cells of 1 n -two cell division cycles (meiosis I & 2) -produces gametes -chromosomes cross over

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

Prophase I -Chromatids form -Homologous chromatids pair up to form tetrads

Metaphase I -tetrads line up at equatorial plate -Crossing over: breaking off of arms of chromatids and switching places on another homologous chromosome

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 humans @ 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. 2. 3. 4. Abnormal rates of cell division; uncontrolled Produces malfunctioning cells Kills the organism 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

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 Bone Cell Neuron (nerves) Muscle Cells Skin Cells Cardiac Muscle Stem Cells