Sexual Reproduction: Meiosis and Genetics

Chromosomes and their # Each pair is a HOMOLOGOUS CHOROMOSOME

Fertilization Process Haploid is the 1n Part this refers to When the cells Have half the DNA Diploid is the 2n Which refers to the Zygote ie fertilized Egg or developing person

Meiosis I and 2

Prophase I is special Because crossing over occurs in which homologous chromosomes exchange fragments with each other increasing genetic diversity

Sexual vs Asexal Reproduction No opportunity for crossing over in asexual, everything is an exact CLONE Sexual causes diversity and thus the end result is a new genetically expressed living organism

Mendelian Genetics Each generation of children produced is referred to as F1 or F2 generations and so on Genes in pairs, punnet square for yellow (YY) and green pea (yy): https://www.youtube.com/watch?v=Mehz7tCxjSE you must know these terms too however this also shows punnet squares !!! Only four boxes is for a MONOHYBRID CROSS, 16 is for a DIHYBRID CROSS

Genetics Results Dominant Gene: is one that if the offspring has it, it expresses this gene over the other one which is RECESSIVE. IF TWO RECESSIVE ALLELES/ NO DOMINANT ARE PRESENT THAN THE RECESSIVE GENE IS EXPRESSED In some cases both are expressed in a blended fashion which is known as Codominance Incomplete dominance is when both genes are neither fully dominating the expression so both are expressed but in a mixed fashion One is like having red and white snap dragons produce pink vs having spots on cows that express both brown and white so there is a brown and white spotted coat on the cow The genotype: is the genes in the organism The phenotype: is what is physically seen by the genes expressed

Gene Linkage Sometimes genes come as linked or required to be with another gene in order to be activated, based on the amount of the gene linked, a different range of resulting expressions can occur for example the more linked genes in some flies make their eyes go from yellow, to blue, to purple like a color choice wheel in photoshop

Polyploidy In many species, if they get extra sets of DNA they can express different phenotypes. These are called polyploidy in which extra sets of DNA are available. In flowers it can be used to express different phenotypes and adaptations, in humans it is LETHAL 3n, 4n, 5n, …etc