Meiosis

Karyotype Karyotype- photograph of chromosomes grouped into pairs. Homologous chromosome- chromosome that has a corresponding chromosome from the opposite-sex parent Autosome- chromosome that is a non-sex chromosome Sex-Chromosome- one of the two chromosomes that determine an individual’s sex

Pair of homologous chromosomes

Terms: Diploid- a cell that contains both sets of homologous chromosomes Somatic Cells Represented as 2N Haploid- a cell that contains only a single set of chromosomes and therefore only a single set of genes. Sex Cells- sperm and egg Represented as N

Fill in missing haploid or diploid numbers Organism Diploid (2N) Haploid (N) Chicken 78 ? Dog 34 Corn (Maize) 20 Human 46 Fruit Fly 4

Diploid or Haploid? Haploid- contains only one set of genetic information

Male or Female? Male = XY Female = XX

Reproduction Asexual reproduction – a single individual is the sole parent and passes copies of all its genes to its off spring Sexual reproduction – two parents give rise to offspring that have unique combinations of genes inherited from each parent

Meiosis Form of cell division by which gametes with half the number of chromosomes are produced. Required for sexual reproduction Start with one DIPLOID cell and end up with four HAPLOID cells.

Fertilization The fusion of a sperm and an egg for form a zygote. A zygote is a fertilized egg.

Visit Bozeman Science for Meiosis Video (10 min.) http://www.bozemanscience.com/meiosis Answer the following questions as you watch the video If you are absent on the day we watch this, please watch the video at home.

Bozeman Science Questions 1.) Meiosis is the process by which _________ are formed. In humans, this refers to sperm and eggs. 2.) Circle one: Do all of the Anderson children look identical or different? 3.) Circle the correct answer using the human life cycle flow chart: Gametes are HAPLOID or DIPLOID A zygote is HAPLOID or DIPLOID A human is HAPLOID or DIPLOID

Bozeman Science Questions cont. 4.) Circle the correct answer: Mitosis starts with a cell that is (2N or N) and ends with two cells that are (2N or N) 5.) Circle the correct answer: Meiosis starts with a cell that is (2N or N) and results in four cells that are (2N or N)

Bozeman Science 6.) List the three major methods that cause genetic variation (Why are you so special?) Independent Assortment _____________________- homologous chromosomes exchange portions of their chromatids during meiosis _____________________- Fertilization

From an evolutionary standpoint, the “fittest” gametes will be the ones who win the race….

Meiosis in Detail Meiosis involves 2 rounds of division

Crossing over in detail (color code)

Create a diagram of meiosis and include the following terms 1.) Crossing over 2.) Homologous chromosomes 3.) Diploid (2N) 4.) Haploid (N) 5.) Sex cells 6.) Somatic cells (body cells) 7.) Meiosis