Transcript 2-3-17
1. Please have these Items on your desk. Agenda Science Starters Sheet 1. Which organic bases pair with each other? 2. What do you think the word genetics means? Friday February 3, 2017 Day 1 Table Of Contents 2/3 (Red) DNA Blueprint 2/3 (Blue) Strawberry DNA 2/3 (Purple) Genetics Notes Part 1 2/3 (Red) Bikini Bottom Genetics pg 18 pg 19 pg 20 pg 21 www.sciencequeen.net Whose got Genes? Genes, Heredity, & DNA 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 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 R R r R r Red rose = RR white rose = rr Genotype r R r R r 4 Rr Phenotype 100% Red Rose Baker 2003/2004 Generation 2 (We do) R r R r r r r Red rose = Rr white rose = rr Genotype r R r r r 2 Rr 2 rr Phenotype 50% Red 50% White Baker 2003/2004 Generation 3 (You do) R R r R R R r Red rose = Rr Red rose = Rr Genotype r R r r r 1 RR 2Rr 1 rr Phenotype Baker 2003/2004 75% Red 25% References Slideshow adapted from http://www.scienceclass.net/PowerPoints/Genetics.htm Baker 2003/2004