Genetics
Introduction
GREGOR MENDAL:
THE FATHER OF GENETICS

AT 21 YEARS OLD HE
JOINED THE MONASTARY
IN BRUNN, AUSTRIA
 HIS JOB WAS TO TEND TO
THE GARDEN
 IN 1851, HE ENTERED THE
UNIV. OF VIENNA TO
STUDY SCIENCE & MATH.
 IN MATH HE LEARNED THE
SUBJECT OF STATISTICS

STATISTICS HELPED W/HIS
DISCOVERY OF HEREDITY:
– THE TRANSMISSION OF
CHARACTERISTICS FROM
PARENTS TO OFFSPRING.

MENDAL 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 SATIVUM, AKA:
– GARDEN PEAS!

OBSERVATION OF 7
CHARACT. OF PEAS:
– EACH OCCURRED IN
2 CONTRASTING TRAITS)

USING STATISTICS
MENDAL ANALYZED
THE DIFFERENCES HE
OBSERVED!
1920s. This shows a close up of the garden
area. It is precisely here that Mendel grew his
peas.
PLANT CHARACTERISTICS
1.
2.
3.
4.
5.
6.
7.
PLANT HEIGHT--LONG/SHORT
FLOWER POSITION ALONG STEM--AXIAL OR TERMINAL
POD COLOR--GREEN/YELLOW
POD APPEARANCE--INFLATED/ CONSTRICTED
FLOWER COLOR--PURPLE/WHITE
SEED TEXTURE--SMOOTH/WRINKLED
SEED COLOR--GREEN/YELLOW
HIS OBSERVATIONS:
 FLOWER COLOR :
– PURPLE-FLOWERS  PURPLE FLOWER
– PURPLE-FLOWER  WHITE-FLOWERING

PLANT HEIGHT:
– TALL PLANT SEEDS-->
TALL PLANTS
– TALL PLANT SEEDS-->
SHORT PLANTS
WHY
DO YOU
THINK THIS
HAPPENED?
FLOWER ANATOMY

ANTHER: MALE REPRODUCTIVE PART
 STIGMA: FEMALE REPRODUCTIVE PART
MENDEL’S METHODS

HE CONTROLLED THE
EXPERIMENT BY
CHOOSING HOW THE
PLANTS WERE
POLLINATED.
 POLLINATION:
– POLLEN GRAINS FROM
ANTHER TRANSFERRED TO
STIGMA
P generation: Parents
Alleles
F1 generation: Offspring
Alleles
F2 generation: Offspring of
the F1 generation
DOMINANT & RECESSIVE
Dominant trait: The trait seen or observed
Recessive trait: The masked or hidden trait
PUNNETT SQUARE
TOOL USED TO PREDICT THE
PROBABILITY OF A GENETIC CROSS.
 CAPITAL LETTER “A” REPRESENTS
DOMINANT ALLELE
 Allele: Variation of a Gene

– Gene: Eye color Alleles: Brown, Blue, Hazel

LOWERCASE LETTER “a” REPRESENTS
recessive ALLELE
Important Terms

Genotype: The genetic blueprint
or what the letter (allele)
represents. Letter combinations
– Examples: TT, Tt, tt

Phenotype: How an allele looks;
the physical appearance
– Examples: Tall and short
Important Terms
•Homozygous: An organism with two
alike alleles.
•Homo. Dominant
•2 Capital letters
•Ex. ZZ, BB, FF
•Homozygous Recessive
•2 lower case letters
•Ex. tt, bb, gg
•Heterozygous: An organism with two
different alleles for a trait.
•Heterozygous Dominant: One
capital letter and one lower case
•Ex. Gg, Hh, Zz
Punnett Square
Examples
PUNNETT SQUARE
EXAMPLES