Electron Micrograph of Chromosomes taken from a somatic cell. In humans, the diploid (2n) number of chromosomes is… 46 chromosomes: 23 from dad, 23 from mom. Electron Micrograph of Chromosomes taken from a somatic cell.

Karyotype – a picture of all the chromosomes in a cell of an organism Single-stranded chromosomes… What stage of mitosis was this cell in? Anaphase or telophase Homologous pairs are arranged by size and banding pattern; Pairs 1  22 are autosomes; Pair 23 = sex chromosomes (XX = female, XY = male) Pair #23 Only males have a Y chromosomes. Who determines baby’s gender? Dad does! (sperm can have X or Y, egg can only have X) Chromosomes (human) during prophase

The Making of a Karyotype We Start Here

Karyotype Practice Learn Genetics – University of Utah (in class) The Biology Project Karyotype Activity (homework) Answer on a separate sheet of paper: Patient karyotypes and diagnoses (Qs #1 & 2); Add brief description of genetic disorder/syndrome (research) A1, A2 B1, B2 C1, C2

Rick’ Go over sex chromosomes Go over autosomes Empahssize that all cells have genetic information, 2 of a kind vs 1 of a kind, somatic cell vs germ cell

Which is male Female Somatic cell or Germ cell Go over Autosomes and Sex Chromosomes Do a chromosome count

T R I P L O I D H A P L O I D

Add the term Homologous / Homologue N or 1N, 1 of a kind 2N, 2 of a kind, A homologous pair Egg cell or Sperm Cell Body Cell Finger Biology A term used to decribe if the cell is Haploid or if the cell is Diploid

46 2 Female Male Mom Dad Autosomes

Autosomes 44 22 1 Chromosome #1 is the largest and gets smaller as you progress to Chromosome #22……………………………………….. therefore Chromosomes #1 has more DNA and Chromosome #22 has the least amount of DNA

Cell A Cell B Cell B Cell A

Somatic Cells have a full set of DNA, 46 chromosomes Gametes have a ½ set of DNA, only 23 chromosomes because the other half of genetic material comes from the other parent during fertilization

(see meiosis slides)

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Meiosis & Sexual Reproduction In most sexually reproducing species, organisms have two sets of chromosomes (2n, diploid), one from each parent…

Being diploid is awesome because… …you get a backup copy of each gene!!!

Sexual reproduction is awesome because… … it creates genetic diversity in a population…

… which increases the chances that at least some will survive challenging environmental conditions.

Meiosis Keeps the species’ number of chromosomes constant from one generation to the next by creating haploid gametes ↓ Creates genetic diversity in gametes through crossing-over and random assortment of chromosomes Allows for the sexual recombination of genetically diverse gametes (during fertilization), creates genetically different individuals