Genetics

212/11/12

WHAT IS GENETICS?

From Wikipedia:

Genetics - the science of genes, heredity, and the variation of organisms

Who Are You?Who Are You?

Better TreatmentsBetter TreatmentsBetter MedicineBetter Medicine

712/11/12

FOR THOUSANDS OF YEARS, PEOPLE WERE DOING GENETICSWITHOUT EVEN KNOWING IT,

THEY SELECTED THE TRAITS IN PLANTS AND ANIMALS THAT THEY WANTEDAND BRED FOR ONLY THOSE TRAITS

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Gregor Mendel

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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 THEF1 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 KERNELS: ______ (YOURS) ________ (CLASS)

PURPLE KERNELS: ______ (YOURS) ________ (CLASS)

TOTAL KERNELS: ______ (YOURS) ________ (CLASS)

RATIO YELLOW TO PURPLE: ________ (YOURS) ______ (CLASS)

YELLOW VS. PURPLE CORN KERNELS RATIOS AND PERCENTS

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THE BIGGER THE SAMPLE SIZE,

THE MORE THAT “ACTUAL” = “EXPECTED”

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ARE WE MISSINGSOMETHING?

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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AaAa

Aa SO A REGULAR CELL

Reproduces through Mitosis and

ends upWith two cells the

same As the parent

THESE ARE CALLED:DIPLOID CELLSBECAUSE THEY

HAVE 2 ALLELES FOR A

TRAIT

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QuickTime™ and ampeg4 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 ampeg4 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 BECOMESTHE CHILD….WITH TWOCHROMOSOMES

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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) ________

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