Transcript short genetics

Genetics
WHAT IS GENETICS?
From Wikipedia:
Genetics - the science of genes, heredity,
and the variation of organisms
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Who Are You?
Better Treatments
Better Medicine
FOR THOUSANDS OF YEARS, PEOPLE WERE DOING
GENETICS
WITHOUT EVEN KNOWING IT,
THEY SELECTED THE TRAITS
IN PLANTS AND ANIMALS THAT THEY WANTED
AND BRED FOR ONLY THOSE TRAITS
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Gregor Mendel
Introducing the Punnet Square!
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TERMS TO REMEMBER:
GENOTYPES: exactly what gene alleles are carried
PHENOTYPES: what shows on the surface
DOMINANT (TT) / RECESSIVE (tt)
HOMOZYGOUS/HETEROZYGOUS (TT/Tt)
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GREGOR MENDEL, A EUROPEAN MONK
IN THE 1800S,
RESEARCHED PEA PLANTS
HE CAME UP WITH THIS:
1.The inheritance of each trait is determined by "units" or "factors”
passed on to descendents unchanged (Alleles on our genes)
2. For each trait, an individual inherits one such unit OR ALLELE
from each parent
3. That a trait may not show up in an individual but can still be passed on
to the next generation.
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Genetic Research isn’t new
• Genetic modification to corn has been going on for
almost 9000 years.
• Even “modern” hybrid corn development started in
1908 with the discovery of Hybrid Vigor
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Hybrid Vigor
• Cross two corn plants with favorable
characteristics
• The “hybrid” seed produced from the mating
would be superior to both parents when
planted and grown.
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Corn Hybrids: the Superheroes
of corn?
WHO is the parent?
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LET’S TALK RATIOS AND PERCENTAGES
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ALBINO: GREEN CORN RATIOS AND PERCENTS
GREEN PLANTS: ______ (YOURS) ________ (CLASS)
WHITE PLANTS: ______ (YOURS) ________ (CLASS)
TOTAL PLANTS: ______ (YOURS) _______ (CLASS)
RATIO
GREEN/WHITE: ______ (YOURS) _____ (CLASS)
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GREGOR MENDEL:
“EXPECTED RATIOS” FOR THE
F1 AND F2 GENERATIONS:
F1 = ALL DOMINANT: 100%
F2 = 3 DOMINANT: 1 RECESSIVE
75% : 25%
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BUT, JUST BECAUSE WE EXPECT SOMETHING,
DO WE ALWAYS GET IT???
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YELLOW VS. PURPLE CORN KERNELS
RATIOS AND PERCENTS
YELLOW KERNELS: ______ (YOURS) ________ (CLASS)
PURPLE KERNELS: ______ (YOURS) ________ (CLASS)
TOTAL KERNELS: ______ (YOURS) ________ (CLASS)
RATIO
YELLOW TO PURPLE: ________ (YOURS) ______ (CLASS)
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THE BIGGER THE SAMPLE SIZE,
THE MORE THAT “ACTUAL” = “EXPECTED”
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ARE WE MISSING
SOMETHING?
LET’S TAKE A STEP BACK
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Regular body cells (2 alleles/trait)
reproduce
in a process called:
MITOSIS
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Aa
Aa
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Aa
SO A REGULAR CELL
Reproduces through
Mitosis and ends up
With two cells the same
As the parent
THESE ARE CALLED:
DIPLOID CELLS
BECAUSE THEY HAVE
2 ALLELES FOR A TRAIT
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QuickTime™ and a
mpeg4 decompressor
are needed to see this picture.
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BUT WAIT A MINUTE…
•IF EACH PARENT CELL HAS 2 ALLELES FOR A TRAIT
•AND THE TWO PARENT CELLS COMBINE,
•WOULDN’T YOU HAVE A SEED WITH 4 ALLELES?
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PLANT SEEDS:
- POLLEN FROM THE “DAD”
- AN EGG FROM THE “MOM”
-A SEED WITH ALLELES FROM BOTH PARENTS
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BUT POLLEN AND EGGS ARE NOT REGULAR CELLS.
THEY HAVE HALF THE CHROMOSOMES.
THAT MEANS HALF THE ALLELES
THEY ARE HAPLOID CELLS
HOW CAN THIS HAPPEN?
(Hint: Remember we mentioned Meiosis earlier???)
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QuickTime™ and a
mpeg4 decompressor
are needed to see this picture.
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SO IN MEIOSIS:
A DIPLOID CELL (WITH 2 ALLELES),
DOUBLES TO 4 ALLELES
THEN
SPLITS INTO 4 HAPLOID CELLS (1 allele each)
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AT FERTILIZATION,
ONE ALLELE FROM EACH PARENT COMBINES TO FORM:
THE EMBRYO THAT
BECOMES
THE CHILD….
WITH TWO
CHROMOSOMES
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Dr. Peter Balint-Kurti
•
The genetic basis for
quantitative disease resistance in maize.
also known as partial disease resistance,
•
–
Usually it is enough to protect the plants
Grant from the National Science Foundation
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WRITE DOWN YOUR RESULTS
AND SET THEM ASIDE…...
HEADS ( YOUR GROUP) ________
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TAILS (YOUR GROUP)
________
TOTAL FLIPS (YOURS)
________
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WITH ALL THAT MIXING AND SPREADING
OF ALLELES,
HOW DO WE PREDICT WHO ENDS UP WITH
WHAT TRAIT???
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Dr. Balint-Kurti’s research:
•
The genetic basis for:quantitative disease
resistance in maize.
•
It also known as partial disease resistance,
•
Usually it is enough to protect the plants
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