Some individuals are able to bend their thumb back at the distal joint at 50° or more
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Transcript of Some individuals are able to bend their thumb back at the distal joint at 50° or more
Some individuals are able to bend theirthumb back at the distal joint at 50° or more
Human Heredity
PTC Taster
• The ability to detect a specific taste from the chemical phenylthiocarbamide (PTC) has been labeled as the trait PTC Tasting or Taster..
• The gene for this trait has been mapped to the long arm of chromosome 7.
Individual Phenotypes
Thumb Tongue Roll Little Finger Earlobes PTC
Bent Straight Roller Non-roller Bent Straight Free Attached Taster non
Thumb Tongue Roll Little Finger Earlobes PTC
Bent Straight
Roller Non-roller
Bent Straight
Free
Attached
Taster
non
# of student
s
% of student
s
Class Phenotypes
How do the class data compare to the actual answers?
BentPinky Straight Dominant
Roller DominantNon-roller
Thumb Bent DominantStraight
Free DominantAttached
Taster Dominantnon
Heredity
DNA- deoxyribonucleic acid, stores genetic information
NOVA Online | Cracking the Code of Life | 9 min, 6 min
Gene- a segment of DNA that codes for a trait
Heredity
Chromosome-
rod-shaped body, found in the nucleus, made of the DNA molecule
Chromatin- loosely stored, relaxed DNA 25 to 30 THOUSAND genes at “rest”
Mendel’s “factors”Are Chromosomes!video clip
Karyotyping
• In your lab tutorial, you looked at three patients who needed diagnosis.
For all three patients, what was the trouble?• Specifically A? B? C?
Last name lineup, check in Lab Notes
Genetics- field of biology, study of heredity
Heredity- how characteristics are passed from parent to offspring
These black Labrador puppies are purebred—their parents and grandparents were black Labs with very similar genetic makeups.
• The parents of these puppies were a mixture of different breeds – Their behavior
and appearance is more varied as a result of their diverse genetic inheritance
• WHO WAS HE?– Father of Genetics– Monk who lived in mid-1800s– worked with pea plants and researched heredity
Gregor Mendel
Figure 9.2A, B
FLOWER COLOR
FLOWER POSITION
SEED COLOR
SEED SHAPE
POD SHAPE
POD COLOR
STEM LENGTH
Purple White
Axial Terminal
Yellow Green
Round Wrinkled
Inflated Constricted
Green Yellow
Tall Dwarf
Mendel observed 7 different plants characteristics of peas. These characteristics were called traits…
• Three Key CHOICES-– Control over the breedings– Use of purebred plants for Parent Gen.– Written observations of “either-or” traits
G. Mendel
Figure 9.2A, B
FLOWER COLOR
FLOWER POSITION
SEED COLOR
SEED SHAPE
POD SHAPE
POD COLOR
STEM LENGTH
Purple White
Axial Terminal
Yellow Green
Round Wrinkled
Inflated Constricted
Green Yellow
Tall Dwarf
Mendel Cont.
• Peas are great to study because – Only two possible
characteristics per trait– they easily cross-pollinate– and have many offspring!
• Trait- a category that has two or more contrasting characteristics– Ex- seed color
What are each of the traits shown in the pairs below?
FlowerColor
FlowerPosition
SeedColorSeedShapePodShape
PodColor
StemLength
Mendel’s Experiments
• In Mendel’s plant experiments, he used special names to describe each generation of pea plants
• P1 generation- parent generation
• F1 generation- offspring of parent generation
• F2 generation- offspring of F1 generation
Mendel and his Experiments- Video
RESULTS 1 Removed stamensfrom purple flower
White
Stamens
Carpel
PurplePARENTS(P)
OFF-SPRING
(F1)
2 Transferred pollen from stamens of white flower to carpel of purple flower
3 Pollinated carpel matured into pod
4 Planted seeds from pod
Dominant- (capital) a trait that covers another
Recessive- (lower-case letter) trait that is hidden by a dominant gene
Survey 5 people (including yourself)Based on your data,
is a Widow’s peak dominant or recessive?
What is your genotype?(Hint: assign letters for Widow’s peak and no Widow’s peak)
• different forms of a gene that code for a trait• reside at the same place on homologous chromosomes
Example- Bb
Alleles
GENE
Figure 9.4
P a B
DOMINANTallele
RECESSIVEallele
P a b
GENOTYPE: PP aa Bb
HOMOZYGOUSfor thedominant allele
HOMOZYGOUSfor therecessive allele
HETEROZYGOUS
P= purplep = whiteA = axiala= terminalB= budsb= no buds
Mendel’s Laws, Genotype vs. Phenotype- Video
Genotype- genetic makeup of an organism (alleles) Example- PP
Phenotype – physical appearance of an organism
Example- purple colored petals
Figure 9.4
P a B
RECESSIVEallele
P a b
GENOTYPE: PP aa Bb
HOMOZYGOUSfor thedominant allele
HOMOZYGOUSfor therecessive allele
HETEROZYGOUS
gene
P= purple
p = white
A = axial
a= terminal
B= buds
b= no buds
For those with a widow’s Why is your genotype W?
Homozygous= Purebred = having two copies ofthe same allele; BB or bb
Heterozygous= Hybrid = two different alleles; Bb
Figure 9.4
P a B
RECESSIVEallele
P a b
GENOTYPE: PP aa Bb
HOMOZYGOUSfor thedominant allele
HOMOZYGOUSfor therecessive allele
HETEROZYGOUS
gene
P= purple
p = white
A = axial
a= terminal
B= buds
b= no buds
Review Question
What is the difference between genes and alleles?
Example: Blood type is the gene, what would the alleles be? Pg.205
Should this Dog be named Spot?
L t H A
l T H a
Hair length
Short L Long l
Hair texture
Wiry T Silky t
Hair curliness
Curly H Straight h
Coat pattern
Spot A Solid a
What is his GENOtype?
What is his PHENOtype?
What trait is he Homozygous for?
Mendel: Law of Segregation
From his pea experiments, Mendel believed:
• Each individual inherits 2 copies of every gene.
• During the formation of gametes, the 2 copies of a gene separate “segregate” (1 copy in every gamete).
Parent 1 Parent 2
What happens when the F1s cross?
Law of Segregation Cont.
MONOHYBRID CROSSES
• Monohybrid Cross- involves one pair of contrasting traits– Example- Cross a male
and female, determine the gender of offspring
• Punnett Square- Who? R.C.Punnett, geneticist What? tool used to predict the
outcomes of crosses
Punnett squares Who? P.183
• The Punnett square: grid system for predicting all possible genotypes from a mating (cross).– axis- each parent
possible gametes
– inside grid possible
offspring genotypes
• Punnett square yields ratio of potential genotypes and phenotypes.
Law of Independent Assortment-
Factors for different
characteristics are
distributed to gametes
independently
A dihybrid cross involves two traits.
• Mendel’s dihybrid crosses led to his second law,the law of independent assortment.
• The law of independent assortment states that allele pairs separate independently of each other during meiosis.
• Mendel’s dihybrid crosses with heterozygous plants yielded a 9:3:3:1 phenotypic ratio.
Dragon Lab
Mom Dad Alleles in
Egg
Alleles in
Sperm
Baby
Phenotype
Genetics and Probability• Probability- the likelihood that a specific
outcome will occur– Expressed as: a fraction, decimal ratio, or %– In a basic Punnett Square, you have four 4
boxes so your ratios could be 1:4 (25%) , 2:4(50%) , 3:4(75%) , 4:4 (100%)
Mendel’s works : 126 red: 122 white 126/248 = 50.8 % P(red)
Your Notes look like this…
EACHWILLBE A SEPARATEEXAMPLE
PunnettSquares
Example 1: Homozygous x Homozygous
Homozygous for purple PP = purple Homozygous for white pp = white
Genotypic Ratio: Phenotypic Ratio:
Example 2: Homozygous x Heterozygous
Homozygous for black coat BB Heterozygous for black coat Bb
Genotypic Ratio: Phenotypic Ratio:
Example 3: Heterozygous x Heterozygous
Heterozygous for black coat Bb Heterozygous for black coat Bb
Genotypic Ratio: Phenotypic Ratio:
Example 4: Testcross- individual of unknown genotype is crossed
with a homozygous recessive individual
Genotypic Ratio:
Phenotypic Ratio:Homozygous
Recessive
UNKNOWN!Is he BB or Bb?
TEST CROSS
Results tell whether tested individual is PUREBRED or HYBRID dominant.
---Test Cross Ex. Would give 100% Dominant offspring if the individual was PURE for the dominant trait.
---ANY recessive phenotype offspring mean the tested parent must have been HETEROZYGOUS
Test Cross example 2
P1 - ?Unknown Dominant? X Homozygous RecessiveROUND wrinkle
? RR -or- Rr ? We know is [[ rr ]]
F1 - If offspring are ALL round, then unknown parent was ______________
If some offspring phenotype shows wrinkles,then the unknown parent was ___________
Smiley : Genotype vs. Phenotype
• Finished product - Word doc• DUE: Print/Color by Hand = HALL
– POST TO WIKI - Go to YOUR HOUR’s PAGE, Upload Tool
• Title at top : Genotype vs. Phenotype Smiley» Draw Smiley by “INSERT” > Pictures > AutoShapes
– At Bottom: Name your Smiley» Give names: yours & partners» List Hour #
CROSS OFFSPRING ACTUAL RATIO
APPROXIMATE RATIO
Long stem x long stem
787 long 277 short
Green pods x green pods
428 green 152 yellow
CROSS OFFSPRING ACTUAL RATIO
APPROXIMATE RATIO
Peas with axial flowers x peas with terminal flowers
652 axial flowers
206 terminal flowers
Fruit flies, normal wings x curly wings
103 normal wings
92 curly
Oval radishes x oval radishes
25 long radishes
52 oval radishes
28 round radishes
Tongue rollers x tongue rollers
755 tongue rollers
245 non-rollers
Beyond Mendel
More Complex Inheritance& Sex-Linked Traits
Incomplete Dominance
• An inheritance relationship in which a “mix” or blend of the two alleles is produced
Incomplete Dominance
• A cross between round radishes and long radishes produces oval radishes. (incomplete dominance).
A cross between round radishes and long radishes produces oval radishes. (incomplete dominance). If oval radishes were selling for the most money, what would you cross for highest profit?
a. round x round b. round x longc. oval x oval d. long x oval
Co-Dominance
-Both alleles are visible in the phenotype
-examples- Lubber grasshopper or a roan horse--- or my sable corgi !
The lubber grasshopper is a very large grasshopper, and is black with red and yellow stripes.
A. What is the expected genotypic ratio of the F1 generation?
B. What is the expected phenotypic ratio of the F1 generation?
C. What percent is expected to be white?
D. How do incomplete dominance and co-dominance differ?
E. Using your text, explain how blood typing illustrates both complete dominance and co-dominance?
1 RW: 0
1 roan: 0
0%
Example 1: Homozygous x Homozygous
Round (RR) Yellow (YY) seeds crossed with Wrinkled (rr) green (yy) seeds
Genotypic Ratio: Phenotypic Ratio:
Dihybrid Cross
• Mono = One… so Monohybrid cross we were only focusing on ONE trait.
• Di = Bi = Two
Example 1 XSo DiHybrid
cross considers two traits at the same time.
Dihybrid Cross pg. 171Round= R wrinkle= r // Yellow = Y green=y
RY Ry rY ry
RY
Ry
rY
ry
Example 2: Heterozygous x Heterozygous
Round (Rr) Yellow (Yy) seeds crossed with Round (Rr) Yellow (Yy) seeds
Genotypic Ratio: Phenotypic Ratio:
Dihybrid cross GgNn x GgNn
GN Gn gN gn
GN GGNN GGNn GgNN GgNn
Gn GGNn GGnn GgNn Ggnn
gN GgNN GgNn ggNN ggNn
gn GgNn Ggnn ggNn ggnn
Phenotypic ratio: 9 green, smooth:
3 green, wrinkled
3 yellow smooth
1 yellow wrinkled
REVIEW Genetic Crosses
homozygous = having two copies of the same allele
heterozygous = having two different alleles
Genotype- genetic makeup of an organism (alleles)
Phenotype – physical appearance of an organism
1. Guinea pigs1. Black - 2. ____ x ____
white –
3. Punnett square –
4. Genotypic ratio:
5. Phenotypic ratio:
2. Curly vs Straight
C= curly Cc x cc
c = straight
genotypic ratio: 1 Cc : 1 cc
phenotypic ratio : 1 curly: 1 straight
Cc Cc
cc cc
C
c
c c
3. In peas. . .1. Tall - 2. ____ x ____
dwarf –
3. Punnett square –
4. Genotypic ratio:
5. Phenotypic ratio:
The following traits are dominant: +brown eyes+curly hair+attached earlobes+curling tongue.
Which one is Wanda’s mom?
Dad = Brown B?
curly C?
unattached aa
roller R?
Wanda= Brown B?
curly C?
attached A?
roller R?
The following traits are dominant: brown eyescurly hairattached earlobesrolling tongue
MOM 1
Wanda got a from dad, had to get the A from mom, Mom one has a A to give
Probability of 2 coins
Coin #1Coin #2
H H
H T
T H
T T
HH HT
HT TT
1/4
1/4
¼ + ¼ = ½ OR
H
T
H T
Test cross- an unknown genotype is crossed with a homozygous recessive individual
TESTCROSS:
B_GENOTYPES bb
BB Bbor
Two possibilities for the black dog:
GAMETES
OFFSPRING All black 1 black : 1 chocolate
B
b
B
b
b
Bb Bb bb
?
6. In mice, black coat is dominant over white. Outline possible crosses to determine whether a black mouse is homozygous or heterozygous. ___ = black
___ = white
_______ x _bb___(black) (testcross)BB or Bb
Pg 10 #7
If two black mice are mated several times. . .
Results: 23 black : 8 white
What do you know about the parents?
Lubber Grasshopper (co-dominant)
The lubber grasshopper is a very large grasshopper, and is black with red and yellow stripes.
RR = red stripes
YY = yellow stripes
RY = red and yellow stripes
4. Cross two lubbers, both with red and yellow stripes. List phenotypic ratio. 1 red: 2 red and yellow: 1 yellow
In mice. . .Running mice =
Waltzing mice =
Black =
brown =
1. hom. run/hom.black x
hetero run/hetero blk
________ x ________
Phenotypic ratio:
RB
RB
Rb
rB
rb
RRBB
RRBb
RrBB
RrBb
2. ___________ x _____________hetero run hetero run
hetero black pure brown
Answer: 3 run black:
1 waltz black:
3 run brown:
1 waltz brown
Answers to dihybrid practice problems
1. Phenotypic ratio: 4 run black :0
2. Phenotypic ratio: 3 run black
1 waltz black:
3 run brown:
1 waltz brown
3. Phenotypic ratio: 1 run black: 1 run brown
4. Phenotypic ratio: 3 run black: 1 waltz black
Genetic corn
What phenotypes do you see on your cob?
Brown & Smooth (A),
Brown & wrinkled (B),
Yellow & Smooth (C)
Yellow & Wrinkled (D).
Which is dominant?
Brown = Smooth =Yellow = wrinkled =
If the P1 generation was heterozygous for both traits, hypothesize what will be your phenotypic ratio?
Phenotypes 1 2 3 4
Description
Number present llll ll ll l
Class Results
Ratios
brown brown yellow yellow
smooth wrinkled smooth wrinkled
Class Results
brown smooth
Brown
wrinkled
Yellow smooth
Yellow wrinkled
Corn Punnett Square
BS Bs bS bs
BS
Bs
bS
bs
Phenotypic ratio: 9 brown, smooth:
3 brown, wrinkled
3 yellow, smooth
1 yellow, wrinkled
Dihybrid Lab
• In corn, brown kernels are dominant over yellow kernels.
• Smooth texture is dominant over wrinkled.
• Cross a hybrid brown, wrinkled corn with a yellow, heterozygous smooth corn.
• What percent will be brown and smooth?
Pg 22 # 5 Aliens from Mars
_______________ x _______________ hetero for both hetero for both
Aliens from Mars
1. E= 2 eyes
e = 1 eye
T = triangle
t = pentagon2. EeTt x EeTt
A. What is the expected genotypic ratio of the F1 generation?
B. What is the expected phenotypic ratio of the F1 generation?
C. What percent is expected to be white?
D. If for Valentine’s Day a florist wanted all pink flowers, what would be the phenotypes for the parents?
1 RW: 0
Red x white
1 pink: 0
0%
Genetic Word Problems
1. Red is INCOMPLETELY dominant over white
Red = ________ x ________White = pink white
Pink =
RR
WW
RW
RW WW
R W
W RW WW
W RW WW
Genetic Word Problems
2.
Red = ________ x ________White = roan roan
roan =
1. Genotype ratio: 1RW : 1WWPhenotype ratio: 1 pink: 1 white
2. Genotypic ratio 1 RR: 2 RW: 1WWPhenotypic ratio 1 red : 2 roan: 1 white% dominant 50%
3. Genotypic ratio 1 AA: 1AaPhenotypic ratio 1 dominant: 0% dominant 100%
4. Genotypic ratio 1 YyWw: 1 YywwPhenotypic ratio 1 yellow web: 1 yellow hoof% dominant yes 50%