Simple Genetics (One Gene for One Trait) n Mendel s Pea Plants. Tall or short. Round or wrinkled. Etc n Dominant & recessive. n Purebred or Hybrid. n Simple Punnett Squares. Gregor Mendel TEST 1 on SLIDES 1-19 1 n Gregor Mendel was a monk who worked with pea plants in the mid 1800 s. Today he is known as Father of Genetics. He was curious about the factors acting on inheritance. Are there patterns? 2 What is Genetics? n Genetics is the branch of biology that deals with heredity. n Heredity is the passing of traits from parents to offspring. Parents à offspring n Traits are characteristics of an organism. Human examples: height, hair, eye color. 3 1
n Gene: a section/piece of DNA on a chromosome that codes for a specific trait. Alleles = alternate forms of a gene (Ex: Blood type A/B/O). Genes tend to come in pairs (alleles). n DOMINANT: an allele whose trait always shows up in the organism when the allele present. (CAPITAL LETTER) n recessive: an allele hidden by dominant. (lower case letter) n Genotype: genetic makeup; allele combinations. (Ex: BB, Bb, bb) n Phenotype: physical appearance of an organism (Ex: Brown hair) 4 How to make a test cross (aka Punnett Square) Parent #1 alleles Offspring Offspring Parent #2 alleles Offspring Offspring 5 6 2
Diagrams & math can be used to predict the probability that a trait will pass from parent(s) to offspring. Punnet Squares 7 8 Complete this test cross between two purebred pea plants: T T t t T = tall stem t = short stem 9 3
10 11 Where are genes? n Genes & chromosomes come in pairs. Most human cells have 23 pairs of chromosomes in the nucleus containing just under 30,000 genes. 12 4
13 CHROMOSOMES n Half from each gamete (sperm and egg). n But what about asexual reproduction??? 14 Code Conservation n All species on Earth use the same chemical code (GTCA). Biodiversity comes from SNP s along a gene sequence. 15 5
Must Know n Allele n Chromosome n DNA (GTCA) n Dominant n Gene & Genetics n Genotype n Heterozygous n Heredity n Homozygous n Hybrid n Meiosis n Mutation n Offspring n Phenotype n Probability n Punnett Square (Cross) n Purebred n Recessive n Traits Terms Challenge n Central Dogma n Co-dominance n Dihybrid cross n Diploid n Haploid n Histones n Gametes n Locus (Loci) n Mutagen n Pedigree chart n Purines (A & G) n Pyrimidines (T & C) 16 Challenge Mendel s Dihybrid cross n We can look at two traits simultaneously using a dihybrid cross. n Consider shape & color in peas R: round r: wrinkled Y: yellow y: green Cross two heterozygotes RrYy x RrYy Try in your notes now! 17 RY Ry ry ry RY Ry ry ry 18 6
19 GENETICS PART TWO -COMPLEX- NON-MENDELIAN 20 DNA Structure understood 1953 Watson & Crick Rosalind Franklin 21 7
DNA *Human Genome mapped in 2003 22 Central Dogma DNA à mrna à Protein 23 The Limits of Mendel s work n Mendel s experiments with pea plants looked at one gene for one trait. This pattern of inheritance is called Mendelian.. Some examples: Cheek dimples, face freckles & cleft chins Tom Bradyà n Few human traits actually obey this model 24 8
Genetics - part one Polygenic Traits Most human traits are polygenic, which means they are controlled by multiple genes. This leads to a wide array of phenotypes. Simple Punnett squares do NOT work for polygenic traits. EX: Human height & eye color. 25 Dynamic Development (GxE) Genes interact with their environment (GxE) In other words, there is a relationship between your genetics & the way you live your life. Nutrition, hormones, sensory input, physical and, etc Epigenetics: Markers & tags (i.e. methyl groups), along with histones affect the epigenome of an organism. 26 Mutations Mutations are changes in the DNA bases. G. T. C. A. Change can be letter addition, substitution, deletion or inversion. Mutations can be good, bad or indifferent to an organism. Mutagens are agents capable of causing a mutation, such as UV light or certain chemicals. 27 9
Genetics - part one Mutations & Evolution Mutations drive evolution. Since all living things use the same chemicals (G.T.C.A.) for their code, changes are necessary to give rise to new species. A concept better known as genetic variation. Observed at the taxonomic levels (D.K.P.C.O.F.G.s.) Genetic Variation à Biodiversity. 28 Glowing mutant mice, frog/duck genetic mutants. 29 Drug resistant bacteria, mushroom mutant, lungfish, tomato mutations. 30 10
Genetics - part one 31 Quotes: It s not that I m so smart, it s just that I stay with problems longer. -Albert Einstein. I'm not out there sweating for three hours every day just to find out what it feels like to sweat. -Michael Jordan. Some people want it to happen, some wish it would happen, and others make it happen. -Michael Jordan. 32 CALGENE 1994-1997 First GM Tomato approved by FDA 33 11
Genetics - part one Human Genome Project 1987-2003. [~3.3 billion base pairs] Faroe Islands (Denmark) ~ 50,000 People. Genome sequencing project for entire population (2013) 34 12