Mendel’s 5 Principles of GeneticsTraits, or characteristics, are passed from one generation to the nextThe traits of an organism are controlled by genesOrganisms inherit genes in pairs, one gene from each parentSome genes are dominant, whereas others are recessiveDominant genes hide recessive genes when both are inherited by an organism (Hh and Rr)

Mendel’s Laws:Law of Segregation: Alleles (genes) occur in pairs that separate during the formation of gametes (more on those in a second) so that every gamete receives only one member of a pair.

Law of Dominance: One of each pair of these alleles dominates the other in expression. Characters are inherited alternately on an “all or nothing” basis.

Gametes: A mature male or female germ cell capable of forming a new individual by the fusion with a gamete of the opposite sex.

Example: sperm or egg cells

Zygote: A cell formed by the union of two gametes. The developing individual produced from such a union is called the “zygote”.

Genotype: The genetic make up of an individualExamples: XY, XY, Hh, HH, Rr, etc.

Heterozygous: A genotype of an organism where the gametes are “different”Examples: Hh, RrHomozygous: A genotype of an organism where the gametes are “the same”

Examples: HH, RR

Phenotype: The visible characteristics of an organism that are produced by the interaction of the genotype and the environment.

Examples: male, female, Hairy, Heavy, round eyes

Genetics: The study of heredity, or the passing on of traits from an organism to its offspring.Gene: Basic unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.Trait: Another word for a characteristic of an organismAlleles: Gregor Mendel:

Natural Selection: Variation------Caused by Genetics-----either you Adapt to environment (and survive) or you don’t Adapt (and die), based on these variations.THE BEST VARIATIONS survive to pass on their variations to their offspring.EVENTUALLY, all the species have these variations.THIS IS: NATURAL SELECTION

Variation just means Differences between OrganismsAll living things in the world are different—we say that they show variation.

Two Types of Variation:Continuous Variation-The feature can vary over a range of values.Examples of this are things like height, weight, skin color, intelligence, leaf area, etc. where the feature can have any value at all (within a certain range).

The smooth distribution curve drawn shows much better the continuous way that values of height in women can actually vary.

Discontinuous Variation-The feature can only take certain values.Examples of this are things like eye color or blood group where there are just a few options, NOT a whole continuous range.The chart below for blood group shows just four distinct values. There is not a continuous range of values.

Darwin's Theory of Evolution:

• An adaptation is a trait that helps an organism be more suited to its environment• Darwin decided adaptations develop over time• Natural selection is also called "survival of the fittest"

SO, DARWIN’S CONCLUSIONS

There is Variation within all species

Differences in SpeciesThis results from genes and inheritanceSome mutations occur, giving organism new variations

Overproduction of offspring

Each species produce more offspring than can survive

Struggle for Existence

All organisms must compete for:FoodWaterLiving SpaceSome organisms will get these, others will not. Those who get these things survive and pass on genes to their offspring while those that do not get these things die.

NATURAL SELECTION

Individuals with certain variations will compete more successfully than those that do not have these variations. They will breed and pass the variations on to their offspring.The organisms will then become more and more populated with individuals having that variation that gives them an advantage

New speciesLamarck (1744-1829) was first to state that descent with modification occurs and that organisms become adapted to their environmentsInheritance of acquired characteristics was the Lamarck belief that organisms become adapted to their environment during their lifetime and pass on these adaptations to their offspring

Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves; known as the Law of Use & Disuse

           1.  Four Components                a.  Individuals of a species vary.                b.  Some variations are genetically determined.                c.  More individuals are produced than live to grow up and reproduce.                d.  Individuals with certain genetic variations are more likely to survive and reproduce than those with others.