BIOL 310 1st Edition Lecture 1 Outline of MendelismI. What is Genetics and Who is Mendel?A. What were early explanations for trait inheritance?II. Model organisms and their common traitsIII. Mendel’s Method of InheritanceIV. How does Mendel’s findings differ from the previous hypotheses? Current Lecture:i. What is Genetics and who is Mendel?What are early examples of “Genetics?” - Selective breeding- Genetic disorders- Genetic VariationWhat were early explanations for how traits were inherited?- God- Blending – taking 2 traits & rubbing them together (blue + yellow = green)- Lamarkian Inheritance – every body part has a gemule (internal buds that expand upon usage), those that are used often are expressed more (giraffes have long necks because they stretch them to reach high branches)- Preformation – greek principal that the egg and/or sperm contain a tiny baby that starts to grow after sex. Ovists – moms ovaries contain the baby Spermists- Dads sperm contains the babyWhy is Mendel so important to modern Genetics?- He picked 2 very different and noticeable traits and mated them to show that blending did not occur.- Counted and determined ratios of each generation, kept great records, established reciprocal process with all traitsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Established the concept of True Breeding- Tall homozygous (TT) ×Tall homozygous (TT) = Tall homozygous (TT)- PUBLISHED his finding- he would not be credited with his discoveries had he not published his findings, he is credited with many other studies that were around the same time because he published!Why still study Genetics?- We don’t know everything there is to know!ii. Model organisms and their traitsGood Model Organism Traits- Small genome- Easy and cheap to care for- Breed quickly and produce a lot of babies- Short growth time- Adaptable to captivity- Easy to study and see traits that you want to study- Genetically transforable- Homologous genome“Model” Genetic Organisms, which and why?- Pea Plantso Dominant & recessive traits were the only traits studiedo Grow quicklyo Easy to control reproduction through induced pollinationo Phenotypes are easy to see and counto The study subjects could be used for food for the monestary!- E. Colio Basic genome o Fast to reproduce- Yeasto Simplest eukaryoteo Fast to reproduce- Miceo Similar to us (have similar DNA sequences for corresponding development)o More closely related to us than yeast or flies- Fruit Flieso Highly fecund (lots of babies)o Lots of phenotypes that can be manipulated through extensive knowledge of their short genome- Zebra Fisho Lots of babieso Transparent (to help with research on embryo development)o Simple to make mutations- Round Wormso Small genome- Other more controversial model organisms due to expenses and ethics:o Dogs & catso Primateso Pigsiii. Mendel’s Method of InheritanceWhat did Mendel actually do?- He intercrossed plants with contrasting traits.o Phenotype – expression of a gene (physical trait; tall, green, round, wrinkled)o Inter-cross – true breeding individuals of different phenotypesTest Crosses:Tall × Short = tallYellow × Green = yellowRound × Wrinkled = roundSmooth × Indented = smoothGreen × Yellow = greenAxillary Flower × Terminal Flower = axillaryViolet Flower × White Flower = violet flowerWhat he observed from these crosses was that each offspring either showed one parent or the other in each characteristic rather than a blending of the two.Progeny of inter-cross are referred to as first filial or F1 generationNow, F1’s also referred to as:- Hybrids / Heterozygous (Tt)Among F1, observed:- All offspring look like 1 parent (traits not total!) or the othero Example: offspring from a round green plant × wrinkled yellow plant may come out wrinkled green but it looks like either ONE trait or the other not a mash up of both!Do these observations agree with the ancient “hypothesis?”- No, blending did not occur and no intermediate phenotypes occurredHow did Mendel interpret these results? (terms he created)- Dominant – masks the recessive trait- Recessive – present in some generations but not F1’s; is not completely eradicated as previously thoughtiv. How does Mendel’s findings differ from the previous hypotheses?Are there other hypotheses consistent with the results?- Paramutation: One allele converts the other into its own traito Green pea changes yellow allele to green- Destruction: One allele destroys the other; only strong gametes surviveWhat are the predictions of each hypothesis?- Masking – F2 will be a mixture of both alleles (blue × yellow = green)- Paramutation – F2 will only present one allele (tall OR short)- Destruction – F2 will only present one allele (tall OR short)Test Cross = Parent × F1 GenerationMendels next test: F1 × F1Were there any consistencies among the data?- Always 2 phenotypes were present- 3:1 ratioWhich hypotheses are CONSISTENT with these data and how?- Masking – because they phenotype that was masked in the first generation, when crossed with arecessive true breed, produces recessive phenotypes. o Tt × tt = Tt, Tt, tt, tt  A mixture of both tall and short plants!Which hypotheses are INCONSISTENT with these data and how?- Paramutation & Destruction because if the recessive alleles had been destroyed the cross would still produce all dominant plantso TT (paramutated) × tt = Tt, Tt, Tt, TtWhat else did Mendel do?- Looked at 2 traits at