Genetics: all the rage in bio One of the fastest changing fields in biology People started studying...
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![Page 1: 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.](https://reader031.fdocuments.in/reader031/viewer/2022032722/56649cda5503460f949a428c/html5/thumbnails/1.jpg)
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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
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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
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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
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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
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Why garden peas?
2. Had a variety of characters to explore
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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
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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
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What he concluded
1. There are different forms of each unit that determine heritable traits (alleles)
2. Principle of __________: During the formation of egg and sperm the parental alleles segregate then the diploid status of the offspring is restored at fertilization
3. Principle of Independent assortment: Each trait is inherited _________ from _____________. They segregate on their own
4. Law of dominance and recessiveness: Within each pair of alleles, there is an option for a ________ (fully expressed) and ______________ (largely unexpressed) variations
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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
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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
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Monohybrid cross: pod color(2 generations)
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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?
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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 _____________ ______________.
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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!
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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)
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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
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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
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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
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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!
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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?
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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 ________
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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.
Changes in DNA during replication
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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