How Mendel studied Inheritance in Peas
Mendel crossed plants with each of the seven contrasting characters he was studying, and studied their offspring.
Mendel's Conclusions about Inheritance
1. Biological inheritance is determined by factors that are passed from one generation to the next (these factors are now called genes).
2. Principle of Dominance
Principle of Dominance
States that some alleles are recessive, and others are dominant.
How Geneticists Use the Principle of Probability
It is used to predict the outcome of a genetic cross.
How Geneticists use Punnet Squares
It is used to compare and contrast the genetic information that will result from a cross.
The Principle of Independent Assortment
States that genes for different traits can segregate independently during the formation of gametes, and helps account for the many genetic variations observed in plants, animals and other organisms.
Inheritance Patterns (other than Independent Assortment)
Incomplete dominance, codominance, multiple alleles, and polygenic traits.
Meiosis vs. Mitosis
Mitosis results in genetically identical diploid cells, whereas Meiosis produces four genetically different haploid cells.
Structures that actually assort Independently
Chromosomes (individual genes don't)
How Gene Maps are produced
If two genes are close together, the recombination frequency between them should be low, since crossovers are rare. If they are far apart, the recombination rates between them should be high.
Process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell
Cells undergo a round of DNA replication, forming duplicate chromosomes (before Meiosis I starts).
Prophase I (Meiosis I)
Each chromosome pairs with its corresponding homologous chromosomes to form a tetrad.
Metaphase I (Meiosis I)
Spindle fibers attach to the chromosomes.
Anaphase I (Meiosis I)
The fibers pull the homologous chromosomes toward opposite ends of the cell.
Telophase I and Cytokinesis (Meiosis I)
Nuclear membranes form. The cell separates into two cells.
Prophase II (Meiosis II)
Meiosis results in two haploid daughter cells, each with the half the number of chromosomes as the original cell.
Metaphase II (Meiosis II)
The Chromosomes line up in a similar way to the Metaphase way of Mitosis.
Anaphase II (Meiosis II)
The sister chromatids separate and move toward opposite ends of the cell.
Telophase II and Cytokinesis (Meiosis II)
Meiosis II results in four haploid (N) daughter cells.
Haploid vs. Diploid
A diploid cell contains both sets of homologous chromosomes, and haploid cells contain only a single set of chromosomes. (for instance, drosophila diploid number is 8 so the chromosome number is N=8, and the haploid chromosome number is N=4)
When each F1 plant flowers and produces gametes, the two alleles segregate from each other so that each gamete carries only a single copy of each gene. Therefore, each F1 plant produces two types of gametes- those with the allele for tallness and those with the allele for shortness.
one of a number of different forms of a gene