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Chapter
10
Mendel
And
Meiosis
Chapter 10 – review notes
 Monohybrid- cross involving one trait
 Dihybrid – cross involving two traits
 Crossing Over- Exchange of genetic
material between homologous
chromosomes
 Crossing over results in greater genetic
recombination
 Alleles – alternate forms of genes
 Punnett Square – used to predict the possible offspring of
crosses between different genotypes.
 Gametes – produced by each parent and shown along the
sides of the punnett square
 Heredity – passing on of traits from parents to offspring
 Law of independent assortment – inheritance of alleles do
not affect different traits as long as the genes for the traits
are on separate chromosomes
 In meiosis, law of independent assortment, the way in
which a chromosome pair separates does not affect the
way other pairs separate.
 Fertilization – uniting of the male and female
gametes
 Pollination – The transfer of male pollen
grains to the female organ
 Homozygous – Alleles present for a trait are the
same (BB; bb)
 Heterozygous – Alleles present for a trait are
different (Bb)
 Recessive- Gene trait that can be masked by a
dominant trait
 Recessive – represented a (lower case) letter
 Dominant – Gene that can mask the
corresponding allele. ( Capital letter)
Meiosis
 Process that makes haploid cells
 produces gametes (sex cells)
 reduction division. It reduces the number of
chromosomes by ½.
 Reduces one diploid cell (2n) into four
haploid cells (n)
 Males – spermatogenesis
 Females - Oogenesis
Meiosis
 Enables each parent to contribute genes to the offspring
 Haploid or (n) – cell that contains only one member of
each chromosome pair.
 Egg - gamete that contains genes contributed only by the
mother
 Sperm – gamete that contains genes contributed only by
the father
 Disjunction will occur / crossing over / replication occurs
only once/ chromosomes will separate twice
 Ensures variation from generation to generation
MEIOSIS
 One Diploid cell to 4 Haploid cells
 Human diploid (46)
 Two stages (Meiosis I & Meiosis II)