variations on a theme. what characteristics are shared by each of these species? species...
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Variations on a Theme
What characteristics areShared by each of these Species?
Species Characteristics
Individualcharacteristics-make a person unique
Although your genes carry your
master plan there are other factors
that makeyou
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 DivisionAnd the Cell Cycle
What is the cell cycle?
The life cycle of a cell
Interphase Mitosis Cytokinesis
Prophase
Metaphase
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
Prophase
Whitefish Onion
Metaphase
Whitefish Onion
Anaphase
Whitefish Onion
Telophase
Whitefish Onion
All Together Now
Uses of Mitosis
• Growth
• Repair and replace old or damaged cells
• Asexual reproduction
MEIOSIS
Forming Gametes for Sexual Reproduction
Who discovered meiosis?
Van Beneden Studying 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
• 2nd division doubles the number of cells
Meiosis
Comparison of Mitosis and Meiosis
Compare Metaphase:Mitosis Metaphase Meiosis Metaphase I
Compare Anaphase
Mitosis Anaphase Meiosis Anaphase I
Compare Daughter Cells Produced:
Mitosis Meiosis
Purpose of Meiosis
• To form gametes for sexual reproduction
• Four viable sperm are produced from spermatogenesis
• One viable egg produced from oogenesis
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 Sperm Forming of Eggs
Meiosis Vocabulary
• Sexual Reproduction-The fertilization (union) of haploid gametes to produce offspring that are not genetically identical to either parent