IB Topic 10 Genetics Notes PDF.notebook
October 23, 2015
Topic 10 ­ Genetics and Evolution
10.1 ­ Meiosis
Essential Idea: Meiosis leads to independent assortment of chromosomes and unique composition of alleles in daughter cells.
Oct 13­5:35 PM
Oct 13­5:36 PM
Vocabulary Review
Review: Meiosis is a reduction division of the nucleus to form haploid gametes.
http://www.stolaf.edu/people/giannini/flashanimat/celldivision/meiosis.swf
gametes
heterozygous
homozygous
haploid
diploid
homologous chromosomes
sister chromatids
centromere
allele
chromosome
replicated
Oct 13­5:44 PM
Oct 13­5:38 PM
10.1 Learning Targets
Chromosomes replicate in interphase before meiosis
Crossing over is the exchange of DNA material between non­sister homologous chromosomes
Crossing over produces new combinations of alleles on the chromosomes of haploid cells
10.2 Inheritance
Essential idea: Genes may be linked or unlinked and are inherited accordingly
Chiasmata formation between non­sister chromatids can result in an exchange of alleles
Homologous chromosomes separate in meiosis I
Sister chromatids separate in meiosis II
Independent assortment of genes is due to the random orientation of pairs of homologous chromosomes in meiosis I
Oct 13­6:41 PM
Oct 21­5:34 PM
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IB Topic 10 Genetics Notes PDF.notebook
Completion and analysis of Punnett squares for dihybrid traits
Review: Punnett squares for monohybrid traits
October 23, 2015
Dihybrid cross of unlinked genes
EX: Yellow pea color is dominant to green and smooth texture is dominant to wrinkled. Cross two heterozygous individuals.
Alleles
Parent phenotypes
Y = Parent genotypes
y = S =
In a certain plant yellow fruit is dominant to white fruit. A heterozygous plant with yellow fruit is crossed with a plant with white fruit. Determine the probable offspring. Possible gametes
s = Brown hair is dominant over light colored hair. Cross two light haired people. Oct 21­6:57 PM
Mendel stated that individual traits are inherited independently from other traits
Oct 22­7:53 PM
Oct 21­7:09 PM
Thomas Hunt Morgan discovered an exception to this rule of independent assortment
His experiments uncovered sex­
linkage of eye color in fruit flies (Drosophila)
Oct 22­8:00 PM
Gene loci are said to be linked if on the same chromosome
Loci = the location of a gene on a chromosome
Linked genes are often inherited together
Oct 21­5:38 PM
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