Transcript All possible green x green in Blue world?

Sickle Cell and the
Hydrophobic effect
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Greasy (uncharged) molecules ARE NOT attracted
to each other
In the presence of water, they end up getting stuck
together because water would ‘rather’ interact with
itself because of its ability to make hydrogen bonds
and the lack of greasy molecules ability to make
hydrogen bonds
Greasy molecules are EXCLUDED from water and
this makes them appear attracted to each other,
but this is NOT what is going on
Look back at the ‘Molecular World Tutorial’
assessor (questions 36 – 41) to review this (it is
why oil and water don’t mix)
It may very well show up on your next quiz
Fetal Hemoglobin
• I made a mistake - serine is NOT
negatively charged, it is just not able to
become positively charged as histidine is
in the presence of Hydrogen ions
• Due to the lack of a full positive charge,
DPG cannot interact with this serine (fetal
hemoglobin) the way it can interact with
histidine (adult hemoglobin)
• Serine is also smaller than histidine
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
Scaling
• A gene is
~1,000-100,000
basepairs*
• A chromosome
is tens or
hundreds of
thousands of
genes
*Includes control regions & stuff that
won’t make it into the final product
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
Phenotype to
Genotype
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 problemsolving techniques
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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?
http://talkbudgies.com/showthread.php?t=41797
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?
Remember Gameter?
So…
• How many blue-budgie genotypes in a
‘blue-budgie’ 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-budgie’ world
• Develop a sure path to the budgie
genotypes regardless of which ‘world’
Bruce’s Punnetting
Use the whiteboard
Pick a heterozygote genotype for one parent
(otherwise, the square may not be illustrative)
Have students pick 2nd genotype
Put up empty square
Ask what genotypes of sperm/eggs each geno
can produce; illustrate filling Punnett row/col
labels
Fill Punnett contents
Path
Blue dominant world
Cross two blues: generally get all blue (ex.
Bb x Bb)
cross 2 greens: always all green
Green dominant world
Cross two blues: always all blue
cross 2 greens: generally get all green (ex.
Gg x Gg)
How will you know
what’s dominant?
• Two COMPETING 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
•What
First: Blue
Dom – which
=>
crosses
yieldgenos
all blue?
dominant appearance
All green?
• Recessive phenotype
• All possible blue x blue in Blue world?
• All possible green x green in Blue
world?
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’
Lab Instructor: Why ‘Total Victory’ ?
x_Plorer
• If you cross Blue with Green
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 50100% chance of inheriting the gene, depending on
how they inherited their dimple genes.”
http://www.wisegeek.com/what-are-dimples.htm
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
Meiosis & Phenotype
Work on Project