Meiosis & Phenotype Taking care of genetic information; figuring it out from a standing start

Meiosis & Phenotype Today we’ll: Refine problem-solving skills Explore all strategies & outcomes to determine the best one –And save hours on homework

Mendel Mattered “The laws governing inheritance are for the most part unknown; no one can say why the same peculiarity in different individuals of the same species, or in different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characteristics to its grandfather or grandmother or more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes, or to one sex alone, more commonly but not exclusively to the like sex.” --Charles Darwin, The Origin of Species

Today… We will figure out the dominant trait and genotype for a set of individuals There will be no luck, no guessing needed We will generate and explore all (simple) hypotheses and rule out those that do not fit, until only one viable one remains

Thinking it Through Develop lines of ‘pure breeding’ traits (green and yellow peas) Cross them… ONLY yellow trait is evident –TWO hypotheses? –One test?

Thinking it Through Two Hypotheses Make a prediction –IF ‘this’ is true, THEN… Model and test

A gene is ~1, ,000 basepairs* A chromosome is tens or hundreds of thousands of genes *Includes control regions & stuff that won’t make it into the final product Scaling

Vocab Revisited Gene: A stretch of DNA that represents all the information for a product as well as when and where to make the product Allele: A version (or flavor) of a gene; two alleles of the same gene my differ by a nucleotide or dozens of them--generally a small number Dominant/recessive: Two alleles enter; one allele leaves (which version manifests in the organism) NOT which version is more common! Genotype/phenotype: Underlying cause; outward appearonce

Pheno to Geno Deducing the latter from the former

Working Through Which traits are dominant? What are individual genotypes? You can use sex to find out! Today we’ll engage in some specific problem- solving techniques Combinatorial thinking Enumerating hypotheses ‘Last one standing’ Orderly approaches & record keeping

Vocab and Symbols Allele: A version (or flavor) of a gene; two alleles of the same gene my differ by a nucleotide or dozens of them –Common symbolism: B vs b or BLU vs blu Homozygous: ‘same pairing’ = has identical alleles (AA, aa) Heterozygous: ‘different pairing’ = has different alleles (Aa)

What’s Dominant? Imagine you are confronted with two phenotypes (color) Can you tell which is dominant? What crosses should you do to quickly assign dominance & genotype?

Occam’s Razor? What? “No more things should be presumed to exist than are absolutely necessary.” So, how many alleles should we assume, and what sort of relationship?

Remember When? Where do sperm and eggs come from? (Process) How many alleles for each trait/gene in each gamete? When doing Punnett squares, what do the ‘letters’ represent?

So… How many blue-booby genotypes in a ‘blue-booby’ world?” What do your offspring look like from blue x blue? Ways to make green in a ‘blue’ world? What if it’s a ‘green-booby’ world Develop a sure path to the booby genotypes regardless of which ‘world’

How will you know what’s dominant? Two hypotheses? Blue is dominant vs Green is dominant First: Blue Dom – which genos => dominant appearance Recessive phenotype All possible blue x blue in Blue world? All possible green x green in Blue world?

How will you know what’s dominant? Two hypotheses? Blue is dominant vs Green is dominant First: Blue Dom – which genos => dominant appearance Recessive phenotype All possible blue x blue in Blue world? All possible green x green in Blue world? What crosses yield all blue? All green?

More Punnetts Keep your blue work Start ‘again’ in a Green World

Whatcha got? Which models can explain all green offspring? Anything useful? How useful to cross to ‘same’ organisms? –‘need’ heterozygotes –How do you get them if you don’t know?

A better way? Need more room? Open x_plorer Graded exercise – show me ‘Total Victory’ and explain what/why you won (100% or 0%)

MORE Vocab Naming is hard. Your parents are their parents’ children. So what’s a parent & what’s a child? In x_plorer: parents stay parents Formally, you will hear P1, F1, F2 in crosses P1: the initial parents for the events in question F1: First filial (of pertaining to, or benefiting a son or daughter) F2: Second filial

x_Plorer An exercise to guide you in thinking Simultaneously consider two alternative hypotheses about dominance (left half; right half) Work through BOTH cases until you have an ordered set of tests (algorithm) to distinguish (i.e. rule one OUT) Watch the lavender box for ‘what to do next’

x_Plorer If you cross Blue with Red and get… Then….

How ‘good’ is the Interweb? “The genetics of dimples is actually rather interesting. Dimples are a dominant trait, which means that it only takes one gene to inherit dimples. If neither of your parents has dimples, you shouldn't have them either, unless you experience a spontaneous mutation. If one of your parents has dimples, you have a 25-50% chance of inheriting the gene, since it means that parent inherited the gene from one or both parents. If both of your parents have dimples, you have a % chance of inheriting the gene, depending on how they inherited their dimple genes.”genetics trait, which What do you have? IF… THEN

How ‘good’ is the Interweb? “The genetics of dimples is actually rather interesting. Dimples are a dominant trait, which means that it only takes one gene to inherit dimples. If neither of your parents has dimples, you shouldn't have them either, unless you experience a spontaneous mutation. If one of your parents has dimples, you have a 25-50% chance of inheriting the gene, since it means that parent inherited the gene from one or both parents. If both of your parents have dimples, you have a % chance of inheriting the gene, depending on how they inherited their dimple genes.”genetics trait, which

Phenos to Genos NOW the fun!!!!

MendelStar! Given the outcome, can you predict the genotype of the parents? Observe, Hypothesize, Predict, Model/Test Have a plan Write it down

MendelStar! For practice purposes, use the ‘Just Mendel’ option If NOT logged in, tutorial in main lab walks you through ‘mating and sorting’ (Show Me... menu) If all that color & such is bugging you, use the ‘Image Simplify’ menu to focus on 1 trait When not logged in, go to the ‘Evaluate’ destination for a list of the genotypes in play

Mate your own Butterflies! Once logged in, choose ‘Find the Genotype’ Work through problems –Have a plan –Write it down! (IF this is TRUE…) –Saves time! After answering, hit submit; if score < 76 you’ll get a hint You can store at any time by submitting

Mate your own Butterflies! Why 76 points ‘max’? Yep, written part in dropbox Really, have a plan

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