Law of Independent Assortment
The inheritance of 1st genetic trait is NOT dependent on the inheritance
of the 2nd trait.
Inheritance of height is independent of the inheritance of flower color.
Ratio of Tall to short is 3:1
Ratio of Red to white i
The two alleles for each trait separate during gamete formation. This
now called: Mendel's Law of Segregation
Law of Segregation
Showed that the Particulate Model best fit the results.
Phenotype - the phy
Sexual Sources of Genetic Variation
Independent Assortment of Chromosomes during Meiosis.
There are 23 pairs of chromosomes in humans.
The chance to inherit a single chromosome (maternal or pater
Chapter 14 Mendel and the Gene Idea
The passing of traits from parents to offspring.
Humans have known about inheritance for thousands of years.
The scientific study of the inheritance.
Genetics is a relatively new science (about 150
Basic steps same as in prophase of Mitosis.
Synapsis occurs as the chromosomes condense.
Synapsis - homologous chromosomes form bivalents or tetrads.
Longest phase of division.
Tetrads or bivalents ali
One flower as both parents.
Natural event in peas.
Results in pure-bred offspring where the offspring are identical to the
Used seven characters, each with two expressions or traits.
Character - height
Number of chromosomes in a "set" for an organism.
Or, how many different kinds of chromosomes the species has.
Usually shown as N =
Humans N = 23
2 sets of chromosomes.
Most common number in body or somatic cells.
Humans 2N = 46
Corn 2N =
Centrioles now at opposite ends of the cell.
Chromosomes line up on the metaphase plate.
Spindle apparatus fully developed.
Centromeres break and the duplicated chromosomes are pulled away from
each other toward opposite ends o
Animal Cell - Mitosis
Evolution of Mitosis
Regulation of Cell Division
Must be controlled.
Rate of cell division depends on the cell type.
Ex - skin: frequently
liver - as needed
brain - rarely or never
A critical control point i
M-phase Promoting Factor.
Protein complex required for a cell to progress from G2 to Mitosis.
Role of MPF - to trigger a chain of protein kinase activations.
Active MPF has:
Amount remains constant during cycle.
Need two parents.
Good gene combinations can be lost.
Offspring may not be an improvement over the parents.
Do parents give their whole DNA copy to each offspring?
What would happen to chromosome number if they did?
Chapter 13 Meiosis and Sexual Life Cycles
Does Like really beget Like?
The offspring will resemble the parents, but they may not be exactly
This chapter deals with reproduction of life.
The transmission of traits from parents