Hello Mr. Schooner’s 7 th Grade Class!!

* DNA contain genes that occupy a specific place on a chromosome. * A chromosome is a rod- shaped structure made of DNA and proteins. * DNA determines a specific trait in the organism, like eye color or gender. * Dogs have 78 chromosomes: 38 pairs of autosomes and 2 sex chromosomes. * Sex chromosomes determine the differences between male and female (X or Y). Males have X and Y chromosomes while females have two X chromosomes. * Autosomes have the information for the traits that both male and female have.

* An allele is an alternative form a gene that determines a characteristic. * Alleles are represented by letters. Capital for dominant alleles and lowercase for recessive alleles. * For example, D can mean the dog will have dark fur and d can mean the dog will have light fur. * Sex cells receive one chromosome from each pair and when combined, the offspring will get one allele from each parent.

* Homozygous is to have the same from of the gene represented by letters. i.e. TT (dominant), tt (recessive) * Heterozygous is to have different froms of genes represented by one capital letter and one lower case letter. i.e. Tt Eye Color Tall or Short

* A dominant trait is a trait that overpowers a recessive trait represented by a capital letter on paper. * A recessive trait can be masked/hidden by the dominant trait. It is represented by a lowercase letter of the first letter for the dominant trait. * i.e. If the dominant trait is brown eyes and the recessive trait is blues eyes, the dog is more likely to have brown eyes. But it is still possible for the offspring to have blue eyes.

* A Phenotype is the physical characteristic/ trait of an organism that can be detected using any of the five senses. i.e. big ears * The genotype is the actual genes on the chromosomes that can’t be detected with five senses. They are represented by letters on paper i.e. TT, Tt, tt * Genotypes code for Phenotypes!! Code for

* Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell. * The cells made are sex cells: sperm in males and egg in females. * When a baby is made one cell from the father (sperm) joins with one cell from the mother (egg). * The new cell that is formed (zygote) contains information stored in DNA to make a new puppy.

Punnett Squares are used to predict the possible outcomes of the puppy. The center boxes represent fertilized eggs. The two columns and rows represent the female chromosomes and the male chromosomes. i.e. If the parents have genotypes Aa x Aa, the Punnett Square will look like this  AA Aa aa Aa A a

* Natural Reproduction is the mating of two different types of dogs. (mutts) * Selective Breeding is controlled mating between two of the same type of dog. * Natural Reproduction increases genetic variation because it introduces new genes to the breed. * Selective Breeding decreases genetic variation because it doesn’t introduce new genes to a breed. Bulldog/ Dalmatian Hybrid Purebred Beagle

* Dog trainers use Selective Breeding to put their dogs in dog shows and make money off pure bred puppies (very expensive) * If they keep doing this there will be no new genes in the bloodline, which can cause health problems for future offspring. * Selective Breeding has large impacts on genetic variation.  It can cause offspring to get a genetic condition like heart disease, blood disorders, immune system disease, etc.  For example, large dogs, like the Great Dane are at a higher risk of getting bone cancer because their bones are so stressed by all the weight they have to carry.

Bone Cancer Chronic eye irritation from excess skin folds Vizsla with skin disease known as atopic dermatitis

* A Pedigree shows how a trait is inherited over several generations. Kind of like a family tree! * If two parents of the same breed are carriers of a genetic disease, it is likely that the puppy will be born with a genetic condition. * These diseases and illnesses can be passed through the pedigree, which can be fatal to the breed.

* Information about genetics from: Postlethwait, John H., and Janet L. Hopson. "Ch. 9 Fundamentals of Genetics." Modern Biology. Orlando: Holt, Rinehart and Winston, Print. * Information about Selective Breeding from: "Dogs That Changed the World - Selective Breeding Problems - Genetics | Nature | PBS." PBS: Public Broadcasting Service. Web. 04 Mar * Pictures from Google Images