2Genetics: all the rage in bio One of the fastest changing fields in biologyPeople started studying it back to ancient Greece but they were limited to PHENOTYPE: what something looks likeDue to our great new knowledge (human genome project and much more) we can now get meaningful information form the GENOTYPE: the genes/ versions that individuals contain
3Historically it was easy to see We all already know too…You look like both of your parents.Each feature is a one or the other kind of thing… not a blendIe. I have my dad’s eyes, my dads mouth shape and my mom’s hands.I am a blend but my features are notIt took Gregor Mendel to start truly understanding WHY
4Mendel changed the world with his peas Mendel had a hypothesis that all of our features were controlled by heritable factors (genes)He set out to prove it but needed a model organism… something that was easy to work with and showed what he needed it tooHe chose the pea plant
5Why garden peas? 1. Easy to control fertilization. Insure self fertilization and cross fertilizationFor cross he removed the stamen before the pollen was mature
6Why garden peas?2. Had a variety of characters to explore
7What Mendel did…First he let the peas self-fertilize so they would be pureHe then crossed a purple flowering plant with a white flowering plant (cross-fertilization or hybrid) This was the _________________ P (parental) generationThe progeny from that generation are F1When the F1 are crossed… their progeny produce what is referred to as F2
8How he did itStarted with plants that differ in only one characteristic (monohybrid cross)Flower color (purple vs white)The F1 progeny were all _______Oh no! Did the white disappear?!?Few… in the F2 generation the white reappeared in a ratio of _____ _______ to _______________So the white was not lost just covered for a while
9What he concludedThere are different forms of each unit that determine heritable traits (alleles)Principle of __________: During the formation of egg and sperm the parental alleles segregate then the diploid status of the offspring is restored at fertilizationPrinciple of Independent assortment: Each trait is inherited _________ from _____________. They segregate on their ownLaw of dominance and recessiveness: Within each pair of alleles, there is an option for a ________ (fully expressed) and ______________ (largely unexpressed) variations
10How we can use itFirst, each trait is named for the _________ version (P for purple because it is dominant) The recessive is just ______ ______ of the (p for white)Each parent can be either homozygous (both alleles the same) or heterozygous (one dominant and one recessive)We track their succession using a Punnett square
11Genes v LookThe genetic makeup of an individual trait is the _________ (heterozygous, homozygous dominant, homozygous recessive)The look of the individual is it’s __________ (purple or white)You can use the genotype to tell the phenotype and sometimes the phenotype to tell the genotype
13Test CrossIf an individual is __________, it is impossible to determine its genotype (could be ___________ __________or _____________)Use a test cross… breed it with a known ____________ ____________What would the F1 look like if the unknown were homozygous dominant?… heterozygous?
14Dihybrid crossesLooks at _____ different characters… seed color and seed shape.If they were inherited together we would see a dominant seed color/shape combo and a recessive comboAs it is the most characters exhibit _____________ ______________.
15Dihybrid example If yellow is dominant to green and round to wrinkled You cross a yellow round seed with a green wrinkled. What do you get?** need a bigger Punnett square!
16Ratios… memorize instead of huge Punnett squares! Heterozygous dihybrid cross always yields a phenotype ratio of _:_:_:_ (dominant both: dominant one: dominant one: recessive both)Homozygous dominant- recessive cross gives all the ______________ (phenotypically the dominant character)
17Incomplete dominance (blend) Not all traits are a one or the other thingWith __________ _________both alleles work together to determine the final phenotypeTake a cross for two flowers… One red (RR) and one white (WW)With incomplete dominance the heterozygote is an ___________ between the two homozygotesNow both the genotypic and phenotypic ratios are 1:2:1 in a heterozygote cross
18CodominanceEach allele is __________ _________in different regions or cellsCalico cat, rone horseNeither one is totally dominant and the two traits co-exist without bothering each other, each controlling their own area
19Blood types are codominant A or B or both or neither may be expressedIf you have __antigens you recognize things with ___ and fight anything with ___If you have AB you recognize _________If you have O you recognize no one but they don’t detect youA donates to __B donates to __AB can receive from anyone but only donate to ABO can donate to _______ but only receive O
20Linked traits Some traits do not independently assort We know that chromosome have loci, all the loci on the same ___________ HAVE to be inherited together (unless crossover moves them)Genes on the same chromosome are inherited together!
21Sex linked traits Sometimes the link is with a sex chromosome. The __ is notorious for being linked… color blindness, hemophilia, and MANY other things in other animalsWho would be more likely to be affected? Why?
22Sex-Linked continued_______ are usually affected more often because they get only one X… so good gene or bad gene automatically shows upA female has another chance for a second X to cover the bad (or just recessive trait)Females are often ________
23Changes in DNA during replication Deletion: a portion is _____________Where is the dog? Where the dog?____________: a portion is doubledWhere is the dog? Where is the the dog?__________: If a deleted piece reattaches in the wrong orientationWhere is the dog? Where is dog? Where is dog eht?Translocation: removed from chromosome and added ___________ to anotherWhere is the dog? The dog is in the backyard. Where is dog? The dog is in the backyard the.
24Human Genetic Analysis We can display human inheritance using a display called a _______.In a pedigree, _______ are represented by ________ and females by circles .An individual who exhibits the trait is represented by a _____ symbol.A _____________ line between two symbols represents a mating .The ________ are connected to each other by ___________ line above the symbols and to the ________ by _________ lines.Roman numerals (I, II, III, etc.) symbolize generations.AutosomalRecessiveAutosomal dominant