INTRODUCTION TO: GENETICS

IN 139Headings

Vocabulary

Important Information

GREGOR MENDEL: THE FATHER OF GENETICS

• AT 21 YEARS OLD HE JOINED THE MONASTERYMONASTERY IN BRUNN, AUSTRIA

• HIS JOB WAS TO TEND TO THE GARDENGARDEN

• IN 1851, HE ENTERED THE UNIVERSITY OF VIENNA TO STUDY SCIENCE & SCIENCE & MATHMATH

• IN MATH HE LEARNED THE SUBJECT OF STATISTICS

• STATISTICS HELPED W/HIS DISCOVERY OF HEREDITY:HEREDITY:– THE TRANSMISSION OF

CHARACTERISTICS FROM PARENTS TO OFFSPRING.

• MENDEL LATER RETURNED TO THE MONASTERY AND TAUGHT HIGH SCHOOL AND KEPT HIS GARDEN GOING.

• HE STUDIED MANY TYPES OF PLANTS BUT HE IS MOST FAMOUS FOR...

• PISUM SATIVUMPISUM SATIVUM, AKA:– GARDEN PEASGARDEN PEAS!

• OBSERVATION OF 7 CHARACT. OF PEAS:– EACH OCCURRED IN

2 CONTRASTING2 CONTRASTING TRAITS)

• USING STATISTICS STATISTICS MENDEL ANALYZED THE DIFFERENCESDIFFERENCES HE OBSERVED!

1920s.  This shows a close up of the garden area. It is here that Mendel grew his peas. 

1.1. PLANT HEIGHTPLANT HEIGHT---LONG/SHORT

2.2. FLOWER POSITION ALONG STEMFLOWER POSITION ALONG STEM---AXIAL OR TERMINAL

3.3. POD COLORPOD COLOR---GREEN/YELLOW

4.4. POD APPEARANCEPOD APPEARANCE---INFLATED/ CONSTRICTED

5.5. FLOWER COLORFLOWER COLOR---PURPLE/WHITE

6.6. SEED TEXTURESEED TEXTURE---SMOOTH/WRINKLED

7.7. SEED COLORSEED COLOR---GREEN/YELLOW

PLANT CHARACTERISTICS

HIS OBSERVATIONS:• FLOWER COLORFLOWER COLOR :

– PURPLE-FLOWERS PURPLE FLOWER– PURPLE-FLOWER WHITE-FLOWERING

• PLANT HEIGHTPLANT HEIGHT:– TALL PLANT SEEDS-->

TALL PLANTSTALL PLANTS– TALL PLANT SEEDS-->

SHORT PLANTSSHORT PLANTS

WHYWHY DO YOU

THINK THIS HAPPENED?

• ANTHER:ANTHER: MALE REPRODUCTIVE PART

• STIGMA:STIGMA: FEMALE REPRODUCTIVE PART

FLOWER ANATOMYFLOWER ANATOMY

MENDEL’S METHODS

• HE CONTROLLEDCONTROLLED THE EXPERIMENT BY CHOOSING HOW THE PLANTS WERE POLLINATEDPOLLINATED.

• POLLINATION:POLLINATION:– POLLEN GRAINS FROM

ANTHERANTHER TRANSFERRED TO STIGMASTIGMA

• SELF-POLLINATIONSELF-POLLINATION: – The transfer of pollen from the anther of a flower to

the stigma of the same flowersame flower, or to different flowersdifferent flowers on the same planton the same plant. .

CROSS-POLLINATION:CROSS-POLLINATION:

• INVOLVES FLOWERS OF 2 2 SEPARATESEPARATE PLANTS

• THE PEA PLANT THAT MENDEL STUDIED REPRODUCED BY SELF-SELF-POLLINATIONPOLLINATION

• 1ST: SELF-POLLINATIONSELF-POLLINATION CAN BE INTERRUPTED

• 2ND: CROSS-POLLINATIONCROSS-POLLINATION PERFORMED.

• HOW THIS IS DONE:– A) REMOVE THE ANTHER FROM A FLOWER

– B) MANUALLY TRANSFER ANTHER OF A FLOWER ON ONE PLANT TO THE STIGMA OF A FLOWER ON ANOTHER PLANT

• THIS GAVE MENDEL A CONTROLLED EXPERIMENT.

WHAT MENDEL DID…

P1 GENERATION:– PARENTPARENT GENERATION

– MENDEL USED 14 STRAINS14 STRAINS FOR EACH OF THE 14 TRAITS HE OBSERVED

– WHEN PLANTS MATURED HE RECORDED THE NUMBER OF EACH TYPE OF OFFSPRING PRODUCED BY EACH P1 PLANT

F1 GENERATION:• GENERATION OF

OFFSPRING OFFSPRING PRODUCED BY THE P1 PLANT

• FIRST FILIAL FILIAL GENERATION

• THESE THEN SELF-POLLINATED AND COLLECTED SEEDS

F2 GENERATION:–THE PLANTS THAT WERE PRODUCED BY THE F1 GENERATION OF PLANTS

F2

generation

HOW COULD THESE TESTS HELP US UNDERSTAND HOW WE INHERIT OUR

TRAITS?

DOMINANT & RECESSIVEDOMINANT & RECESSIVE• MENDEL CALLED THE

TALL HEIGHTTALL HEIGHT OF THE PLANT DOMINANTDOMINANT– B/C IT HID/MASKED OR

DOMINATED THE SHORT HEIGHT

•THE SHORTSHORT PLANT WAS CALLED RECESSIVERECESSIVE•HOW DOES THIS RELATE TO US?

PUNNETT SQUARE• TOOL USED TO PREDICT THE RESULTS IN

GENETICS

• CAPITAL LETTERCAPITAL LETTER “AA” REPRESENTS DOMINANT DOMINANT ALLELEALLELE

• LOWERCASE LETTERLOWERCASE LETTER “aa” REPRESENTS recessive ALLELErecessive ALLELE

• LET’S DRAW AN ALLELE ON YOUR LEFT PAGE

GENOTYPE & PHENOTYPE• GENOTYPE:GENOTYPE: THE GENETIC BLUEPRINT OR

WHAT THE LETTER (ALLELE) REPRESENTS:– “TT”– “tt”

• PHENOTYPE:PHENOTYPE: IS HOW THE ALLELE LOOKS– “TT” = TALL PLANT– “tt” = short PLANT

• HOMOZYGOUS:HOMOZYGOUS: AN ORGANISM W/22 ALIKEALIKE ALLELES FOR A TRAIT THAT ARE EXACTLYEXACTLY THE SAME (tttt OR TTTT)

• HETEROZYGOUS:HETEROZYGOUS: AN ORGANISM THAT HAS 2 DIFFERENT2 DIFFERENT ALLELES FOR A TRAIT (TtTt)

PUNNETT SQUARE EXAMPLES