Variations on a Theme

What characteristics are Shared by each of these Species? Species Characteristics

Individual characteristics- make a person unique

Although your genes carry your master plan there are other factors that make you YOU!

Like What? Environment Spiritual life

Genetics- The Study of Heredity

Genes A section of DNA that codes for a particular trait (the recipe for a protein)

Chromosomes Threadlike structures composed of DNA and proteins found in the nucleus of the cell.

Chromatid- one of the identical halves of the chromosome Centromere- constricted area where chromatids are joined

Homologous Pairs and Homologues

MITOSIS MEIOSIS Diploid- has two of each chromosome- 2n- product of mitosis Haploid- 1 of each chromosome- 1n- product of meiosis

Humans have 46 chromosomes or 23 pairs of chromosomes

Fruit Flies 8 chromosomes or 4 pairs

Goldfish 100 chromosomes or 50 pair

Crayfish 200 chromosomes or 100 pair

Lilies, Tomatoes, White Pines All have 24 chromosomes or 12 pair It’s not the chromosome number that determines the species but the genes on the chromosomes

What is a Karyotype? A photograph or stained, separated and sorted chromosomes

How many chromosomes would there be in a human diploid cell? A haploid cell?

Haploid cells are for reproduction

What is the difference between a gene and a chromosome?

Cell Division And the Cell Cycle

What is the cell cycle? The life cycle of a cell

Interphase Mitosis Cytokinesis

Mitosis The division of a cell to produce two identical daughter cells

Interphase Chromosomes are copied Appear as “threadlike”coils (chromatin)at the start, but each chromosome and its copy (sister chromosome) change to sister chromatids at end of this phase. Chromatid

Prophase Mitosis begins Centrioles appear Spindle fibers form between the poles

Metaphase Chromatids attach to spindle fibers in center

Anaphase Chromatids separate and begin to move to opposite sides of the cell

Telophase Two nuclei form Chromosomes appear as chromatin (threads rather than rods Mitosis ends

Cytokinesis Membrane moves inward to create two daughter cells with identical chromosomes

Uses of Mitosis Growth Repair and replace old or damaged cells Asexual reproduction

MEIOSIS Forming Gametes for Sexual Reproduction

Who discovered mitosis? Van BenedenStudying Ascaris

Meiosis Vocabulary Zygote- a diploid cell formed by the union of a haploid sperm and egg Meiosis- the forming of sexual gametes by reducing the number of chromosomes from diploid to haploid through two divisions.

Meiosis- two divisions 1st division reduces the # of chromosomes from diploid to haploid 2 nd division doubles the number of cells

Meiosis

Comparison of Mitosis and Meiosis

Compare: Mitosis Metaphase Meiosis I Metaphase

Compare Mitosis AnaphaseMeiosis I Anaphase

Compare: MitosisMeiosis

Purpose of Meiosis To form gametes for sexual reproduction

Meiosis Vocabulary Gametes- haploid cells that, when united, form a diploid zygote- ex. sperm, eg

Meiosis Vocabulary Fertilization- the process of forming a zygote

Meiosis Vocabulary Sperm- male gamete Egg- female gamete

Meiosis Vocabulary Forming of SpermForming of Eggs

Meiosis Vocabulary Sexual Reproduction-The fertilization (union) of haploid gametes to produce offspring that are not genetically identical to either parent