10.2 MENDELIAN GENETICS
WHAT YOU WILL LEARN
-Law of Segregation
-Law of Independent Assortment
-How to use a Punnett square
http://www.youtube.com/watch?v=B_PQ8qYtUL0&feature=emshare_video_in_list_user&list=UUWxJwdNjOFOUvKAhsYo41lg
10.2 MENDELIAN GENETICS
MAIN IDEA
Mendel explained how a dominant allele can
mask the presence of a recessive gene.
READING Q’s
DEFINE
-What is a true breeding plant?
-same form of trait from generation to generation
READING Q’s
LABEL
-Fill in the boxes with the name of each generation of offspring. Draw
the peas you would expect to see in the empty pods. Use shading to
indicate a green pea.
F-1
F-2
READING Q’s
APPLY
-In Mendel’s experiment with green and yellow seeds, what
was the dominant trait?
-yellow seeds
READING Q’s
PREDICT
-What would be the phenotype of a homozygous, recessive
(yy) pea plant?
-green seeds
READING Q’s
APPLY
-True-breeding yellow-seeded and green-seeded plants are
crossed and produce yellow-seeded offspring. Which of
these plants is a hybrid?
-yellow-seeded offspring
READING Q’s
IDENTIFY
-What is one purpose of a Punnett square?
-tracking genotypes/phenotypes
-predicting ratios of cross outcomes
READING Q’s
DEFINE
-Circle the genotypes in the small squares that will give a
yellow-seed phenotypic ratio in the offspring? What will be
the phenotypic ratio in the offspring?
3:1
10.2 READING NOTES
Mendel is considered the “father of genetics”
Mendel used pea plants because they reproduce by
self-fertilization—male gamete combines w/female gamete
Mendel also used cross-pollination—removed male gamete to
combine w/female gamete of a different plant
http://www.youtube.com/watch?v=vIrrtM47Wio
Bill nye greatest discoveries in genetics: 1:25-5:07
10.2 READING NOTES
Pea plants have 7 traits that are independent of
each other—
-height
-flower location
-pod color
-pod appearance
-seed color
-seed texture
-flower color
stem tall/short
yellow/green
constricted/inflated
yellow/green
smooth/wrinkled
purple/white
10.2 READING NOTES
GROUP WORK: APPLICATION NOTES
-As
a group complete the application note sheet
using your knowledge from the reading.
NEW VOCABULARY
DEFINE
genetics
-study of inheritance
heredity
-how traits passed from gen to gen
segregation
-to “separate”
allele
-different possible forms of a gene for a particular trait
HISTORY OF GENETICS
Write 4-bulleted facts about Gregor Mendel, “Father of Genetics”
-Austrian monk, son of peasant farmer,1840s
-attended University of Vienna—studied math, chemistry, physics,
botany, paleontology, plant physiology & statistics
-followed traits in pea plants-discovered how traits were
inheritedbegan study of genetics
-determined traits are a combination from both parents
-1866 published math/methods inheritance in pea plants
MENDEL’S EXPERIMENT
ANALYZE Mendel’s experiment with green-seed and
yellow-seed pea plants by completing the diagram.
generation
P-parental
_______________
F1-first filial
_______________
self fertilization
yellow pea (male)
green pea (female)
cross fertilization

self fertilization
yellow
ALL ___________

F2-second filial
_______________
____
1 green
3 yellow : ____
MENDEL’S EXPERIMENT
DESCRIBE how a plant self-fertilizes:
-male & female gametes come from same plant
DESCRIBE cross-fertilization:
-remove male part of a flower, transfer to female of diff plant flower
INFER why Mendel used cross-pollination to study
inheritance:
-create offspring that have traits from both plants
NEW VOCABULARY
-COMPARE/CONTRAST each pair of terms by defining them
&/or noting their differences.
genotype
allele combination--Rr
phenotype—
traits an individual displays--red
dominant trait—
observed trait masks
recessive trait
recessive trait—
trait observed only if dominant
trait is not present
homozygous—
two of the same alleles for a
trait—RR/rr
heterozygous—
two different alleles for a trait-Rr
pure trait—
homozygous alleles
hybrid—
heterozygous alleles
INHERITANCE OF TRAITS
COMPARE genotypes & phenotypes for pea plants:
genotype
homozygous/heterozygous phenotype
YY
________
homozygous
yellow seeds
Yy
_______
heterozygous
yellow
___________
yy
_______________
homozygous
___________
green
LAW OF SEGREGATION
DIAGRAM: Complete the diagram to demonstrate gamete
formation & fertilization.
grows into plant
gamete
YY yellow pea
formation
fertilization
seed development
grows into plant
gamete
yy green pea
formation
GAMETE FORMATION
F-1 hybrid
Yy = yellow
dominant trait
FERTILIZATION
 LAW OF SEGREGATION
COMPLETE the Punnett square-fill in missing info:
R
R
RR
r
P Rr
r
Rr
rr
 LAW OF SEGREGATION
COMPLETE the Punnett square-fill in missing info:
R
R
RR
r
P Rr
r
Rr
rr
 LAW OF INDEPENDENT ASSORTMENT
DEFINE: law of independent assortment—
-genes for different traits are inherited independently of
each other
 LAW OF INDEPENDENT ASSORTMENT
DEMONSTRATE law of independent assortment by listing
the 4 alleles that are produced when a pea plant with the
genotype RrYy produces gametes—
RrYy
RY
Ry
rY
ry
 LAW OF INDEPENDENT ASSORTMENT
IDENTIFY the genotypes/phenotypes in Punnett square
showing DIHYBRID cross of seed color Yy & texture Rr
YR
Yr
yR
yr
YR YYRR
YYRr
YyRR
YyRr
yellow/round
Yr
YYRr
yellow/round
yR
YyRR
yellow/round
yr
YyRr
yellow/round
yellow/round
YYrr
yellow/wrinkle
YyRr
yellow/round
Yyrr
yellow/wrinkle
yellow/round
YyRr
yellow/round
yyRR
green/round
yyRr
green/round
yellow/round
Yyrr
yellow/wrinkle
yyRr
green/round
yyrr
green/wrinkle
 LAW OF SEGREGATION
COMPLETE
-Punnett squares to show height in F1 & F2 generations
T = tall plants
t = short plants
F1 generation
F2 generation
T
T
T
t
t
T
Tt Tt
TT Tt
t
Tt
Tt
100% Tt
t
Tt
tt
25% TT / 50% Tt / 25% tt
 PROBABILITY
DEFINE: probability
likelihood a specific event will occur
PREDICT PROBABILITIES
-What is the probability of rolling a 5 on a dice?
1 out of 6 = 1/6
-What is the probability of 2 coins landing on heads if you flip 2 coins?
½X½=¼
-What is the probability of rolling a 3 when rolling a die?
1 out of 6 = 1/6
-What is the probability of rolling two 3s on two dice?
1/6 X 1/6 = 1/36
 PROBABILITY
DEFINE: probability
likelihood a specific event will occur
PREDICT PROBABILITIES
-What is the probability of one coin landing on heads if you flip a single
coin once?
1 out of 2 = ½
-What is the probability of 2 coins landing on heads if you flip 2 coins?
½X½=¼
-What is the probability of rolling a 3 when rolling a die?
1 out of 6 = 1/6
-What is the probability of rolling two 3s on two dice?
1/6 X 1/6 = 1/36
COIN TOSS PROBABILITY
PRACTICE PROBABILITY—
-Use 2 coins to show the probability of the occurrence of
HH / HT / TT
-Mendel’s experiments with pea plants did not get exact
9:3:3:1 ratios, however, the more experiments he conducted
the closer the ratios were to the actual.
-You will first flip the coins 10 times to get a ratio
-Then you will flip the coins 100 times to see if the ratio is
closer to the predicted outcome
INHERITANCE OF TRAITS
CHECK -- 10.2 VOC
Genetics is the branch of biology that studies how traits
-__________
are inherited.
Hybrid
-__________
offspring result from parents that have different
alleles
forms of __________
for certain traits.
-Mendel’s ____________________
states that every
law of segregations
individual has two alleles of each gene and when gametes are
produced, each gamete receives one of these alleles.
law of independent assortment state that genes
-Mendel’s ___________________________
for different traits are inherited independently of each other.
INHERITANCE OF TRAITS
COMPLETE the paragraph—
-Mendel was the first person to succeed in predicting how traits are
inherited from generation to generation
__________
gametes
-In peas, both male & female sex cells, called ___________,
are in the
same flower.
-____________________
occurs when a male gamete fuses with a
Self-fertilizations
female gamete in the same flower.
-Mendel used the technique called cross-pollination
_______________ to breed one
plant with another.
trait at a time and analyzed his data
-Mendel studied only one _____
mathematically.
recessive allele of a trait is hidden by
-In a heterozygous genotype, the ________
the expression of the other phenotype. In a heterozygous genotype the
_________
dominant allele of a trait is visible in the phenotype.