Biosci 0815 1st Edition Lecture 13Outline of Last Lecture I. Insertion and Deletion of NucleotidesII. Gene Expressiona. Steps: transcription, Splicing, Translationb. Getting Access to DNAc. HistonesIII. Histone Modificationsa. EpigeneticsIV. Protein ModificationsOutline of Current Lecture I. Mendela. Three existing theoriesi. Spermistii. Ovistiii. Blendingb. Mendel’s approachc. HypothesesII. Organizing traitsIII. HomozygousIV. HeterozygousV. ConclusionsVI. Factors/AllelesVII. Recessive or DominantCurrent Lecture: Basic Mendelian Genetics- Mendel:o Wanted to know how traits are passed from parents to offspring. o Theories: Traits are passed by blending- Offspring represented a blending of fluids from parents. “a black sheep crossed with a white sheep would end up grey” ovist or spermistThese 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.- believed that one or the other was responsible for carrying all of the genetic material. Believed that the other gamete was insignificant or was only for environment. - The homunculus was a fully formed individual jammed into either the egg or sperm. Dismissed other gamete. Acquired traits- Traits present in parents are modified through use over time and are passed ontot he offspring in the modified form. Traits that are used and modified are passed onto children. Ex: blacksmith was predicted to have children with strong biceps. Was dismissed but now is similar to epigenetics.o Mendel’s approach: Used the garden pea as a model. Cheap and reproduces quickly. Can self pollinate. Allowed him to conduct a highly controlled experiment and choose parents to produce offspring.  Examined one trait (monohyprid cross).  Chose discontinuous traits. Means it has to be one thing or another EX: seeds were either wrinkled or smooth. Purple or white.  Continuously bred these true breeders as a control. Wanted to make sure that there were no impurities. o Hypothesis: If blending: W+P = pink, p+p = p Ovist or spermis: ovist: if all femle is purple, all offspring should be purple- Spermist: male is purple, all offsrping are purple Procedure and observation:- Took anthers from purple flower and pollinated from white flower.All offspring had purple flowers.- This is a monohybrid cross. 1 trait two versions of same trait.- Where was the white trait? It was there but the purple color covered it. - Lets f1 offspring self-pollinate. This is f1Xf1 cross. Creates F2 generation. o ¾ of plants in F2 were purpleo ¼ were whiteo P (P+W) = F1 (P) + F1 (P) = F2 (PPPW) Tried this for other traits: tall plants and short plants. Same results in f2 where short was 1/4. Also did for seed shape, pod shape: (smooth/wrinkled), podshape, flower color, seed color, stem length.  Symbols:- P= parents- F1= offspring (first generation).o Learned: the pattern was something that appeared when two factors contributedto an outcome. The one that occurred more frequently was called dominant, if there is any presence of dominant trait, that trait will be expressed. The other is recessive (must have two copies of this, one from each parent for it to be expressed). Each parent contributes genes to the zygote. Purple= P, white = p. a true breeder is either PP or pp (homozygous). A hybrid is Pp (heterozygous) (but it shows the dominant). What results: what we see, is called a phenotype.- Organizing traitso A way of organizing traits is called a Punnett square. It separates the alleles (variety of versions of a trait) and combines them in the offspring- Homozygouso Each of those PP genes make mRNA make proteins that say make the purple pigment.o Pp: translate into an enzyme that does not catalyze reactions to purple color. Could be a different biochemical pathway or could block a step in the production of purple pigment. - Heterozygouso Make two different proteins Pp. Because the P is dominant, it makes enough protein to turn the color purple.- Conclusions:o Factors determine phenotype and some are dominant. Blending is an incorrect theory.- What about ovist and spermist?o Mendel looks at smooth seed coat male pea plants crossed with wrinkled seed coat female pea plants. Resulted in all of them being round.o Then looked at smooth seed female pea plant crossed with wrinkled seed coat male pea plant and F1 was all round. This meant that it was not dependent on male or female gamete. - Factors/alleles;o Mendel referred to the discreet particles that defined traits as factors. We now call them alleles. If you look at a pair of homologous chromosomes, each chromosome has a version/allele specific for that trait. They can be different. They are different versions of the same trait. o Laws of segregation: Only one allele from each parent can be passed down. - Application of Medel’s discoveryo What if you didn’t know the genotype; PP or Pp. You could testcross it with a homozygous individual that is fully recessive. A testcross always has a parent withfully recessive alleles. o If all offspring were purple, parents is PP.o If half offspring are white, half purple, parent is Pp. - Human dominant and recessive traits:o Example is the ability to roll the tongue or not. It is