Patterns of Inheritance AKA Genetics

Genetics: all the rage in bio One of the fastest changing fields in biology People started studying it back to ancient Greece but they were limited to PHENOTYPE: what something looks like Due 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

Historically 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 blend Ie. I have my dad’s eyes, my dads mouth shape and my mom’s hands. I am a blend but my features are not It took Gregor Mendel to start truly understanding WHY

Mendel 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 too He chose the pea plant

Why garden peas? 1. Easy to control fertilization. Insure self fertilization and cross fertilization For cross he removed the stamen before the pollen was mature

Why garden peas? 2. Had a variety of characters to explore

What Mendel did… First he let the peas self-fertilize so they would be pure He then crossed a purple flowering plant with a white flowering plant (cross-fertilization or hybrid) This was the _________________ P (parental) generation The progeny from that generation are F1 When the F1 are crossed… their progeny produce what is referred to as F2

How he did it Started 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

What he concluded There 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 fertilization Principle of Independent assortment: Each trait is inherited _________ from _____________. They segregate on their own Law of dominance and recessiveness: Within each pair of alleles, there is an option for a ________ (fully expressed) and ______________ (largely unexpressed) variations

How we can use it First, 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

Genes v Look The 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

Monohybrid cross: pod color (2 generations)

Test Cross If 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?

Dihybrid crosses Looks 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 combo As it is the most characters exhibit _____________ ______________.

Dihybrid 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!

Ratios… 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)

Incomplete dominance (blend) Not all traits are a one or the other thing With __________ _________both alleles work together to determine the final phenotype Take a cross for two flowers… One red (RR) and one white (WW) With incomplete dominance the heterozygote is an ___________ between the two homozygotes Now both the genotypic and phenotypic ratios are 1:2:1 in a heterozygote cross

Codominance Each allele is __________ _________in different regions or cells Calico cat, rone horse Neither one is totally dominant and the two traits co-exist without bothering each other, each controlling their own area

Blood types are codominant A or B or both or neither may be expressed If 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 you A donates to __ B donates to __ AB can receive from anyone but only donate to AB O can donate to _______ but only receive O

Linked 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!

Sex 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 animals Who would be more likely to be affected? Why?

Sex-Linked continued _______ are usually affected more often because they get only one X… so good gene or bad gene automatically shows up A female has another chance for a second X to cover the bad (or just recessive trait) Females are often ________

Changes in DNA during replication Deletion: a portion is _____________ Where is the dog?  Where the dog? ____________: a portion is doubled Where is the dog?  Where is the the dog? __________: If a deleted piece reattaches in the wrong orientation Where is the dog?  Where is dog?  Where is dog eht? Translocation: removed from chromosome and added ___________ to another Where is the dog? The dog is in the backyard.  Where is dog? The dog is in the backyard the.

Human 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. Autosomal Recessive Autosomal dominant