Which organic base pairs with each other? 1. Please have these Items on your desk. Agenda Science Starters Sheet Strawberry Lab Packet Which organic base pairs with each other? What do you think the word genetics means? Friday February 3, 2017 Day 1

Table of Contents Page 21 2/3 Punnett Square & Genes Notes Baker 2003/2004

Whose got Genes? Genes, Heredity, & DNA www.sciencequeen.net Baker 2003/2004

What are genes? Genes are a segment of DNA on a chromosome that controls a particular trait. Genes are located on the chromosomes in the nuclei. Each organims has a fixed number of chromosomes. Humans have 23 pairs (46) chromosomes. Genetics is the study of how traits are passed on from one generation to another                                    Baker 2003/2004

What is GENETICS? The study of how traits are inherited through the interactions of genes. Baker 2003/2004

Define TRAIT Ways of looking, thinking, or being Traits that are genetic are passed down through the genes from parents to offspring Baker 2003/2004

Describe RECESSIVE A trait that is covered over, or dominated, by another form of that trait and seems to disappear Hidden when the other copy of the gene contains the dominant allele. A recessive allele shows up only when there is no dominant allele present Shown with a lower-case letter Baker 2003/2004

Describe DOMINANT A trait that covers over, or dominates, another form of that trait Trait that always shows up, even when only one of the two alleles is in the dominant form Shown by a capital letter Baker 2003/2004

Define GENOTYPE An organism's genetic makeup Baker 2003/2004

Outward physical appearance and behavior of an organism Define PHENOTYPE Outward physical appearance and behavior of an organism Baker 2003/2004

What is a PUNNETT SQUARE? Used to determine the likely hood that the offspring receives a certain trait. An uppercase letter stands for a dominant allele Lowercase letters stand for recessive alleles Baker 2003/2004

Who is the scientist? Reginald Punnett and William Bateson were among the first English geneticists. Punnett created the Punnett square in 1905. He devised the Punnett square to depict the number and variety of genetic combinations. Baker 2003/2004

Punnett Squares Sample Problem 1.   In roses, red flowers are dominant over white flowers. What are the possible offspring when a homozygous red rose is crossed with a homozygous white rose. Baker 2003/2004

Generation 1 (I Do) R R Red rose = RR white rose = rr R r R r r Genotype 4 Rr Phenotype 100% Red Rose R r r R r Baker 2003/2004

Generation 2 (We do) R r r r R r r Red rose = Rr white rose = rr R r r Genotype 2 Rr 2 rr Phenotype 50% Red 50% White R r r r r Baker 2003/2004

Generation 3 (You do) R r Red rose = Rr R r R R R Genotype Phenotype 75% Red 25% White R r r r r Baker 2003/2004

References Slideshow adapted from http://www.science-class.net/PowerPoints/Genetics.htm Baker 2003/2004