Heredity

__Heredity and Evolution/ Heredity__ Lab #7- Genetics of Organisms How does genetic variation affect appearances of an organism in seperate generations through male vs. female? Hardy Weinberg is an equation used to measure evolution. Five factors affect Hardy Weinberg equilibrium: mutation, gene flow, genetic drift, random mating and natural selection. Because these 5 factors are never achieved naturally, the equation shows the changes in allele frequencies from one generation to the next. Punnet squares predict the genotypes of offspring. Two heterozygous individuals make a 1:2:1 ratio. Heterozygous with homozygous makes a 1:1 ratio. A chi-square analysis uses probabilities to show how accurate data is to reality.

p^2+2pq+q^2=1 p+q=1

Lab 8 Heterozygous genotypes are the most common. When a specific genotype is eliminated from the environment, genetic variation decreases.

Heredity is the passing of traits from parents to offspring. The offspring inherit traits and characteristics from the parents. Variations in a population can cause a species to evolve if some traits are more desirable or suitable for the environment. Alleles can be dominant or recessive, but some are expressed codominantly or incompletely.

__Summary:__ In the cross, the mutation was autosonaml, recessive, and monohybrid. When crossing two homozygous flies, the F1 offsrping will have 100% normal eyes and the F2 offspring will have 75% normal eyes. Fruit flies are used as a model organism because they mature quickly and are easy to care for.

__Vocabulary words and definitions__

· somatic cells-  body cells, all cells other than sex cells (gametes) · gametes-  reproductive/sex cells, sperm and egg · zygotes-  the initial cell formed when two gametes join · sister chromatids- two identical copies of chromatin connected by centromere, separated in mitosis  · karyotypes-  number of chromosomes appearing in nucleus of eukaryotic cell · haploid cells- 
 * Heredity- the passing of traits to offspring.
 * heterozygous- having different alleles at a locus on homologous chromosomes. (Aa)
 * homozygous- having the same alleles at a locus on homologous chromosomes. (AA or aa)
 * phenotype- a specific manifestation of a trait ( size or eye color)
 * genotype- the specific genetic makeup of an individual; usually in the form of DNA
 * allele- A number of viable DNA codings of the same gene occupying a given position on a chromosome.
 * dominant allele- the trait that is expressed when heterozygous is crossed with a recessive allele.
 * punnet square- Crosses the genotypes of a generation to predict the possible genotypes of the next generation.
 * monohybrid cross- Punnet square cross that deals with only one trait.
 * dihybrid cross- Punnet square cross that deals with two traits.
 * pedigree- family tree showing genetic relationships between individuals
 * codominance-both parental alleles are fully expressed.(AB blood type)
 * incomplete dominance- when the heterozygous phenotype is intermediate between the two homozygous phenotypes (AA- red flowers, aa- white flowers, Aa- pink flowers)
 * polygenic inheritance- when several genes affect phenotype ( skin color)
 * law of segregation-
 * law of independent assortment-
 * quantitative characters-
 * pleiotropy- one gene that has more than one phenotypic
 * epistasis- two genes interacting to produce a certain phenotype
 * meisois- []
 * mitosis- []
 * sporophyte-multicellular diploid stage
 * gametophyte- spores dividing mitotically to make multicellular haploids
 * synapsis-crossing over in Prophase I of meosis
 * Chromosome theory of Inheritance- Chromosomes undergo segregation ang independent assortment
 * Aneuploidy- abnormal number of a particular chromosome
 * Polyploidy- two complete chromosome sets.
 * Kinds of Mutation- Deletion, Duplication, Inversion, Translocation

__People and their experiments__:
 * Gregor Mendel is the father of genetics. Through his experiments of pea plants in 1857, he formed the basic principles of heredity which he then applied to people and animals since heredity is essentially the same for all life forms.
 * The Experiment: In this experiment, observed seven different triats of pea plants (seed color, seed shape, flower color, etc) that occur in two different forms. He cross fertilized two different true breeding (pure bred) varieties of peas. In one of his experiments he crossed a true-breeding purple flower (PP: homozygous dominant:) of a pea plant with a true breeding white flower of a pea plant (pp). The F1 generation was 100% purple, heterozygous flowers. He then crossed the F1 gerenation (so a purple heterozygous flower (Pp) with a purple heterozygous flower(Pp)) and the F2 gerneration was 75% purple and 25% white.
 * His conclusions:
 * Law of Segregation: Homologous allele pairs separate during gamete formation, making the sex cell haploid and then the gametes randomly combine during fertilization, so that the resulting offspring cell has two sets of alleles, one from each parent, and the resulting cell is then diploid.
 * Law of Independent Assortment:This explains that when dealing with two traits (like flower color and seed color) the transmission of alleles for one triat does not affect that of the the other trait.
 * Darwin
 * Studied finches on the Galapagos islands and noticed they had different beaks.
 * Established that all species descended from common ancestry.
 * T.H.Morgan:
 * Studied the mutations of //Drosophilia (//fruit flies).
 * Hardy and Weinberg
 * In 1908 G. H Hardy and W. Weinberg suggested that evolution could be viewed as changes in the frequency of alleles in a population of organisms.
 * Came up with Hardy-Weinberg equation which states that the frequency of possible diploid combinations of alleles (AA,Aa,aa) is expressed as p2+2pq+q2=1.0, where p represents the frequency of the dominant A allele and q represents the frequency of the the recessive a allele.
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">Argued that if five conditions were met, the population’s allele and genotype frequencyies will remain constant from generation to generation. However these conditions rarely exist in nature.
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">1. Large population
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">2. Mating is random (individuals show no preference for a phenotype)
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">3. There is no mutation of the alleles
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">4. No migration occurs
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">5. There is no selection