Transcript Mendel Loved His Peas! - McCarthy`s Cool Science

Assignment #
Mendel Loved His Peas!
Mrs. McCarthy
Biology
April 4, 2016
I. Gregor Mendel
A. Father of Genetics
B. Austrian Monk
C. Published his work in
1866
D. Bred different varieties
of garden pea, Pisum
Sativum
1. Garden Peas are good subjects
because:
a. They have many traits with
two clearly different forms
that are easy to tell apart
b. Mating can be easily
controlled. (Self-pollinating
or cross-pollinating)
c. They are small, grow easily,
mature quickly and produce
many offspring=QUICK
RESULTS!
d. Don’t talk back to scientists.
E. First to develop rules that accurately
predict patterns of heredity
1. Heredity- passing of traits from parents
to offspring
2. Genetics- branch of biology that focuses
on heredity
II. Mendel’s Experiment
A.
B.
Step 1: He let the flowers self pollinate for several generations
to get a true breeding variety
Step 2: He then cross pollinated two P generation (first
individuals crossed) plants that had contrasting forms of the
trait
1.
C.
Step 3: he then allowed the F1 generation to self pollinate
1.
D.
F1 Generation- first filial generation (first babies…aww! How cute!)
F2- second filial generation
RESULTS: He found a 3:1 ratio of plants expressing the
contrasting traits in the F2 generation
III. Crossing
A. Monohybrid Cross- a cross that
involves one pair of contrasting traits
Ex. Flower color, wrinkled peas vs.
round peas, height
B. Dihybrid Cross- a cross that involves
two pairs of contrasting traits
Ex. Flower color AND height
C. True Breeding- all the offspring would
display only one form of a particular
trait
D. Allele- different copies or forms of a gene
controlling a certain trait
Ex. T or t (Letters are used to represent
alleles)
E. Law of Segregation- two alleles for a trait
separate when gametes are formed (in
meiosis)
F. Law of independent assortment- alleles of
different genes separate independently of one
another during gamete formation (also in
meiosis)
IV. Dominant vs. Recessive
A. Dominant- the trait that is expressed
1. Shown by a CAPITAL letter
Ex. T
B. Recessive- the trait that is not expressed (hidden)
1. Shown by lowercase letter
Ex. t
C. Genotype- genetic make up
Ex. Tt or TT
D. Phenotype- physical trait
Ex. Short or Tall
E. Homozygous- two of the same alleles for
that trait
1. Purebred
Ex. TT or tt
F. Heterozygous- two different alleles for that
trait
1. Hybrid
Ex. Tt
Trait
Dominant
Recessive
Seed Shape
Round- R
Wrinkled- r
Seed Color
Yellow- Y
Green-
y
Pod Color
Green-
G
Yellow-
g
Stem Length
Tall-
T
Short-
t
Genotype
Phenotype
Homozygous or
Heterozygous?
1
Tt
2
Gg
Green pod
3
YY
Yellow Seeds
Homozygous
Round Seeds
Homozygous
4
RR
Tall
Heterozygous
Heterozygous
5
gg
Yellow pod
Homozygous
6
Rr
Round Seed
Heterozygous
Genotype
Phenotype
Homozygous or
Heterozygous?
7
tt
Short
Homozygous
8
Yy
Yellow seeds
Heterozygous
9
TT
10
rr
Wrinkled
seeds
Homozygous
11
yy
Green seed
Homozygous
12
GG
Green Pod
Homozygous
Tall
Homozygous