Transcript Bikini Bottom Genetics

Chapter 11
Mendel and Heredity
Classical Genetics
Fundamentals of Genetics
Children look like their parents
Ideas on inheritance of traits
– Pangenesis Aristotle (384 - 322 BC)
– Blending Hypothesis
• Traits from parents blend to form offspring
Gregor Mendel
“Father of Modern Genetics”
Austrian Monk (1822-1884)
Experimented with pea plants
in the 1860’s
Work wasn’t discovered until
1900
Mendel’s Pea Plants
Reasons that Garden Peas
worked well
– Flower Structure
• Male and Female Parts
could self fertilize
• Easy to control breeding
Self vs. Cross Fertilization
Self Fertilization – an individual that breeds with
itself
Cross Fertilization – one individual fertilizes
another, had to prevent self fertilization
Quick Life Cycle
Peas mature quickly and produced many
offspring
Seven Easily Observable Traits
Disproving the Blending Hypothesis
Blending hypothesis – offspring are always
intermediates of the parents
Mendel’s Traits didn’t Blend
Tall Plants x Short Plants = Tall Plants
Mendel’s Traits didn’t Blend
Purple Flowers X White Flowers = Purple Flowers
Mendel’s Traits didn’t Blend
Green Peas x Yellow Peas = Yellow Peas
Mendel’s Traits didn’t Blend
Green Pods x Yellow Pods = Green Pods
Mendel’s Experiments
True Breeding (Purebred) – offspring that were
produced by the same type of parents
Hybrid – offspring that were produced by different
types of parents
P (parent) Generation
Mendel crossed plants that were purebred for
different traits
Purebred Tall x Purebred Short = F1
F ( filial ) = offspring
The F1 Generation were hybrids, but showed
only one form of the trait
Mendel stated that this form was DOMINANT
P (parent) Generation
Dominance
Gene – section of DNA that controls a trait
Alleles - the different forms of the gene
When 2 alleles are present, one shows up and
the other is hidden
Dominant Allele – the one that shows up
Recessive Allele – the one that is hidden
F1 Self Fertilization = F2
Mendel allowed the hybrid F1 Plants to self fertilize
The resulting offspring were the F2 generation
The Recessive trait reappeared in the F2 generation
Always in the same ratio
3 dominant : 1 recessive
Mendel’s Conclusions
Each Individual has 2 alleles for a trait
– 1 allele from each parent
Homozygous (Purebred) – both alleles are the
same
– Homozygous Dominant / Recessive
Heterozygous (Hybrid) both forms of the allele
are present
Phenotype vs Genotype
Phenotype – physical traits that can be observed
– Purple Flowers or White Flowers
Genotype – the alleles that an individual has for
a trait
Genotype
Phenotype
– Homozygous Dominant (PP)
– Heterozygous (Pp)
– Homozygous Recessive (pp)
Purple Flowers
Purple Flowers
White Flowers
Law of Segregation
When individuals form gametes (sperm or egg)
the 2 alleles for a trait are separated
Law of Independent Assortment
Different Traits are inherited separately
Flower Color and Seed Color are not tied
together
Monohybrid Cross
Mono – 1
Hybrid – different alleles
Punnett Square
Tool used to predict genetic probability
Phenotypic Ratio
Purple : White
3:1
Genotypic Ratio
Homozygous D : Heterozygous : Homozygous R
PP: Pp : pp
1:2:1
Phenotypic Ratio
Tall : Short
4:0
Genotypic Ratio
Homozygous D : Heterozygous : Homozygous R
TT: Tt : tt
2:2:0
Tongue Rolling
Tongue Rolling is a dominant trait in humans
Hitchhiker’s Thumb
Hitchhiker’s thumb is a recessive trait in humans
Dimples
Dimples are a dominant trait in humans
Free vs Attached Earlobes
Free Earlobes are a dominant trait in humans
Widow’s Peak
Widow’s Peak a dominant trait in humans
Dihybrid Cross
Observing 2 traits parents are hybrids for each
RrYy x RrYy
Gametes ¼ RY, ¼ Ry, ¼ rY and ¼ ry
16 possible outcomes
Easier Way to do multiple traits
x
• Do a separate Punnett Square for each trait
Rr x Rr
Yy x Yy
R
R
r
Y
r
y
RR
Rr
Y
YY
Yy
Rr
rr
y
Yy
yy
3/4 Round
1/4 wrinkled
3/4 Yellow
1/4 green
Easier Way to do multiple traits
x
3/4 Round
•
•
•
•
•
1/4 wrinkled
3/4 Yellow
1/4 green
Muliply the probabilities of each trait
Round and Yellow = ¾ x ¾ = 9/16
Round and Green = ¾ x ¼ = 3/16
Wrinkled and Yellow = ¼ x ¾ = 3/16
Wrinkled and Green = ¼ x ¼ = 1/16
Analyzing Heredity
Probability – the likelihood that an event will
occur
Probability – number of one outcome
number of possible outcomes
Flipping a Coin Heads
Rolling a Dice
1/6
½
Bikini Bottom Genetics
Scientists at Bikini Bottoms have been investigating the
genetic makeup of the organisms in this community.
Use the information provided and your knowledge of
genetics to answer each question.
1. For each genotype below, indicate whether it is a
heterozygous (He) OR homozygous (Ho).
Ho Bb _____
He DD _____
Ho Ff _____
He
Ho dd _____
Ho
TT _____
tt _____
He ff _____
Ho Tt _____
He
Ho BB _____
Ho FF _____
Ho
Dd _____
bb _____
Bikini Bottom Genetics
TT _____ Bb _____ DD _____ Ff _____ tt _____ dd
_____
Dd _____ ff _____ Tt _____ bb _____ BB _____ FF
_____
Which of the genotypes in #1 would be considered
TT, DD, tt, dd, ff, bb, BB, FF
purebred? _______________________________
Which of the genotypes in #1 would be hybrids?
Bb, Ff, Dd, Tt
__________________________________________
Bikini Bottom Genetics
2. Determine the phenotype for each genotype using
the information provided about SpongeBob.
Yellow body color is dominant to blue.
Yellow
Yellow
Blue
YY __________
Yy ____________
yy ___________
Square shape is dominant to round.
Square
Square
Round
SS ___________
Ss ____________
ss ___________
Bikini Bottom Genetics
3. For each phenotype, give the genotypes that
are possible for Patrick.
A tall head (T) is dominant to short (t).
TT, Tt
tt
Tall = __________
Short = ___________
Pink body color (P) is dominant to yellow (p).
pp
PP, Pp Yellow body = _______
Pink body = ______
Bikini Bottom Genetics
4. SpongeBob SquarePants recently met SpongeSusie
Roundpants at a dance. SpongeBob is heterozygous for
his square shape, but SpongeSusie is round. Create a
Punnett square to show the possibilities that would
result if SpongeBob and SpongeSusie had children.
HINT: Read question #2!
S
s
s
Ss
ss
s
Ss
ss
Bikini Bottom
Genetics
S
s
s
Ss
ss
s
Ss
ss
A. List the possible genotypes and phenotypes
for their children. Heterozygous (Ss) Square, Ho
Recessive (ss) Round
B. What are the chances of a child with a square
1
2
50
shape? ____
out of ____
or ____%
C. What are the chances of a child with a round
1
2
50
shape? ____
out of ____
or ____%
Bikini Bottom Genetics
5. Patrick met Patti at the dance. Both of them are
heterozygous for their pink body color, which is
dominant over a yellow body color. Create a Punnett
square to show the possibilities that would result if
Patrick and Patti had children. HINT: Read question #3!
P
p
P
PP
Pp
p
Pp
pp
P
p
P
PP
Pp
p
Pp
pp
Bikini Bottom Genetics
A. List the possible genotypes and phenotypes
for their children.
B. What are the chances of a child with a pink
3
4
75
body? ____
out of ____
or ____%
C. What are the chances of a child with a yellow
1
4
25
body? ____
out of ____
or ____%
Bikini Bottom Genetics
6. Everyone in Squidward’s family has light blue skin, which is
the dominant trait for body color in his hometown of Squid Valley.
His family brags that they are a “purebred” line. He recently
married a nice girl who has light green skin, which is a recessive
trait. Create a Punnett square to show the possibilities that would
result if Squidward and his new bride had children. Use B to
represent the dominant gene and b to represent the recessive
gene.
B
B
b
b
Bb
Bb
Bb
Bb
Bikini Bottom Genetics
B
b
b
Bb
Bb
B
Bb
Bb
A. List the possible genotypes and phenotypes for their children.
100
B. What are the chances of a child with light blue skin? ______%
0
C. What are the chances of a child with light green skin? ____%
D. Would Squidward’s children still be considered purebreds?
Explain!
No, they are all hybrids
Bikini Bottom Genetics
7. Assume that one of Squidward’s sons, who is
heterozygous for the light blue body color, married
a girl that was also heterozygous. Create a
Punnett square to show the possibilities that would
B
b
result if they had children.
B
BB
Bb
b
Bb
bb
Bikini Bottom Genetics
7. Assume that one of Squidward’s sons, who is heterozygous
for the light blue body color, married a girl that was also
heterozygous. Create a Punnett square to show the possibilities
that would result if they had children.
A. List the possible genotypes and phenotypes for their children.
Ho D (BB) Blue, He (Bb) Blue, Ho R (bb) green
75
B. What are the chances of a child with light blue skin? ____%
25
C. What are the chances of a child with light green skin? ____%
Bikini Bottom Genetics
8. Mr. Krabbs and his wife recently had a Lil’ Krabby, but it has
not been a happy occasion for them. Mrs. Krabbs has been
upset since she first saw her new baby who had short eyeballs.
She claims that the hospital goofed and mixed up her baby with
someone else’s baby. Mr. Krabbs is homozygous for his tall
eyeballs, while his wife is heterozygous for her tall eyeballs.
Some members of her family have short eyes, which is the
recessive trait. Create a Punnett square using T for the dominant
gene and t for the recessive one.
T
T
T
TT
TT
t
Tt
Tt
Bikini Bottom Genetics
T
T
T
TT
TT
t
Tt
Tt
A. List the possible genotypes and phenotypes
for their children.
Ho D (TT) tall eyes, He (Tt) tall eyes
B. Did the hospital make a mistake? Explain
your answer. Yes, there is no way that their child could
have short eyes
Bikini Bottom Genetics 2
1. Use the information for SpongeBob’s traits to
write the phenotype (physical appearance) for
each item.
Round Eyes
(a) LL-______________
(e) Rr-_______________
Long Nose
Stubby Nose
(b) yy-_______________
(f) ll- _______________
Blue Body
Round Pants
(c) Ss-_______________
(g) ss- ______________
Square Pants
(d) RR - _____________
(h) Yy -______________
Round Eyes
Yellow Body
Bikini Bottom Genetics 2
2. Use the information in the chart in #1 to write the genotype (or
genotypes) for each trait below.
ll
YY,
Yy
(a) Yellow body - __________ (e) Stubby nose - __________
RR, Rr
ss
(b) Roundpants - __________
(f) Round eyes - ___________
rr
(c) Oval eyes - ____________
(g) Squarepants - __________
SS, Ss
LL, Ll
(d) Long nose - ___________
(h) Blue body - ___________
yy
Bikini Bottom Genetics 2
3. Determine the genotypes for each using the
information in the chart in #1.
Rr
(a) Heterozygous round eyes -_____
SS
(b) Purebred squarepants - ______
LL
(c) Homozygous long nose - ______
Yy
(d) Hybrid yellow body - ______
4. One of SpongeBob’s cousins, SpongeBillyBob,
recently met a cute squarepants gal,
SpongeGerdy, at a local dance and fell in love.
Use your knowledge of genetics to answer the
questions below.
(a) If SpongeGerdy’s father is a heterozygous
squarepants and her mother is a roundpants,
what is her genotype? Complete the Punnett
square to show the possible genotypes that
would result to help you determine Gerdy’s
genotype.
Ss
What is Gerdy’s genotype? _________
S
s
s
Ss
ss
s
Ss
ss
Bikini Bottom Genetics 2
4. One of SpongeBob’s cousins, SpongeBillyBob,
recently met a cute squarepants gal,
SpongeGerdy, at a local dance and fell in love.
Use your knowledge of genetics to answer the
questions below.
(b) SpongeBillyBob is heterozygous for his
squarepants shape. What is his genotype?
Ss
________
Bikini Bottom Genetics 2
4. One of SpongeBob’s cousins, SpongeBillyBob, recently
met a cute squarepants gal, SpongeGerdy, at a local
dance and fell in love. Use your knowledge of genetics
to answer the questions below.
(c) Complete the Punnett square below to show the
possibilities that would result if Billy Bob & Gerdy had
children.
S
s
S
SS
Ss
s
Ss
ss
Ss x Ss
4. One of SpongeBob’s cousins, SpongeBillyBob,
recently met a cute squarepants gal,
SpongeGerdy, at a local dance and fell in love.
Use your knowledge of genetics to answer the
questions below.
(d) List the possible genotypes and phenotypes for
the kids.
SS Ss ss square round
(e) What is the probability of kids with squarepants?
_____
%
75
(f) What is the probability of kids with roundpants?
_____
%
25
S
s
S
SS
Ss
s
Ss
ss
Bikini Bottom Genetics 2
5. Sponge Bob’s aunt and uncle, Sponge Wilma and
Sponge Wilbur, have the biggest round eyes in
the family. Wilma is believed to be heterozygous
for her round eye shape, while Wilbur’s family
brags that they are a pure line. Complete the
Punnett square to show the possibilities that
would result if Wilma and Wilbur had children.
(a) Give the genotype for each person.
Rr
Wilma - _______
Wilbur - ________
RR
5. SpongeBob’s aunt and uncle, SpongeWilma and
SpongeWilbur, have the biggest round eyes in
the family. Wilma is believed to be heterozygous
for her round eye shape, while Wilbur’s family
brags that they are a pure line. Complete the
Punnett square to show the possibilities that
would result if Wilma and Wilbur had children.
(b) Complete the Punnett square below to show the
possibilities that would result if they had
children.
R
R
R
RR
RR
r
Rr
Rr
5. SpongeBob’s aunt and uncle, SpongeWilma and
SpongeWilbur, have the biggest round eyes in
the family. Wilma is believed to be heterozygous
for her round eye shape, while Wilbur’s family
brags that they are a pure line. Complete the
Punnett square to show the possibilities that
would result if Wilma and Wilbur had children.
(c) List the possible genotypes and phenotypes for
the kids.
RR Rr
Round eyes
R
R
R
RR
RR
r
Rr
Rr
Bikini Bottom Genetics 2
5. SpongeBob’s aunt and uncle, SpongeWilma and
SpongeWilbur, have the biggest round eyes in
the family. Wilma is believed to be heterozygous
for her round eye shape, while Wilbur’s family
brags that they are a pure line. Complete the
Punnett square to show the possibilities that
would result if Wilma and Wilbur had children.
(d) What is the probability that the kids would have
round eyes? 100
____ %
Bikini Bottom Genetics 2
5. SpongeBob’s aunt and uncle, SpongeWilma and
SpongeWilbur, have the biggest round eyes in
the family. Wilma is believed to be heterozygous
for her round eye shape, while Wilbur’s family
brags that they are a pure line. Complete the
Punnett square to show the possibilities that
would result if Wilma and Wilbur had children.
(e) What is the probability that the kids would be
0 %
oval eyes? ____
6. SpongeBob’s mother is so proud of her son and his
new wife, SpongeSusie, as they are expecting a little
sponge. She knows that they have a 50% chance of
having a little roundpants, but is also hoping the new
arrival will be blue (a recessive trait) like SpongeSusie
and many members of her family. If SpongeBob is
heterozygous for his yellow body color, what are the
chances that the baby sponge will be blue? Create a
Punnett square to help you answer this question.
1/2 or 50%
Y
y
y
Yy
yy
y
Yy
yy
7. SpongeBob’s aunt is famous around town for her itty,
bitty stubby nose! She recently met a cute
squarepants fellow who also has a stubby nose,
which is a recessive trait. Would it be possible for
them to have a child with a regular long nose? Why
or why not?
Create a Punnett square to help you answer this
question.
l
l
ll x ll
l
l
ll
Stubby
ll
Stubby
ll
Stubby
ll
Stubby
8. If SpongeBob’s aunt described in #7
wanted children with long noses, what
type of fellow would she need to marry
in order to give her the best chances?
Create a Punnett square to help you
answer this question.
L
LL
l
l
Ll
Long
Ll
Long
L
Ll
Long
Ll
Long
Complex Inheritance
Incomplete dominance – neither allele is
completely dominant
RR
rr
Rr
Rr
rr
Rr
Rr
RR
Palamino Horses
Heterozygous (Cc)
CC x cc always produces Cc palamino
Palamino x Palamino
Cc X Cc = 1 CC: 2 Cc : 1 cc
Bikini Bottom Genetics
Incomplete Dominance
Bikini Bottom Genetics Incomplete Dominance
SpongeBob loves growing flowers for his pal
Sandy! Her favorite flowers, Poofkins, are found in
red, blue, and purple. Use the information provided
and your knowledge of incomplete dominance to
complete each section below.
1. Write the correct genotype for each color if R
represents a red gene and B represents a blue gene.
Red - _RR_ Blue - __BB_ Purple - _RB__
Bikini Bottom Genetics
Incomplete Dominance
2. What would happen if SpongeBob crossed a Poofkin with red
flowers with a Poofkin with blue flowers.
Complete the Punnett square to determine the chances of each
flower color. RR x BB
(a) Give the genotypes and phenotypes for the offspring.
RB, purple
(b) How many of the plants would have red flowers? __0__%
(c) … purple flowers? _100_ %
B
B
(d) … blue flowers? __0__ %
RB
R RB
R
RB
RB
Bikini Bottom Genetics
Incomplete Dominance
3. What would happen if SpongeBob crossed two Poofkins with
purple flowers? Complete the Punnett square to show the
probability for each flower color. RB x RB
(a) Give the genotypes and phenotypes for the offspring.
RR
BB
RB
(b) How many of the plants would have red flowers? _25__%
(c) … purple flowers? _50____ %
R
B
(d) … blue flowers? ___25__ %
R
RR
RB
B
RB
BB
Bikini Bottom Genetics
Incomplete Dominance
4. What would happen if SpongeBob crossed a Poofkin with
purple flowers with a Poofkin with blue flowers? Complete the
Punnett square to show the probability for plants with each flower
color.
BR x BB
(a) Give the genotypes and phenotypes for the offspring.
BB
RB
(b) If SpongeBob planted 100 seeds from this cross, how many
should he expect to have of each color?
B
B
RB =1/2 50 plants
Purple flowers - ______
BB =1/2 50 plants
Blue flowers - ______
BB
BB
B
RR = 0 plants
Red flowers - ______
R
RB
RB
Codominance
Both alleles are expressed at the same time
Type AB blood is an example, both A and B
antigens are present.
RR
rr
Rr
Rr
Rr
RR
rr
Rr
Multiple Alleles
ABO blood typing is also an example of
multiple alleles.
Instead of 2 alleles there are IA, IB and i
– IA codes for A proteins
– IB codes for B proteins
– i codes for no proteins
Blood Types
Phenotype
Type A
Type B
Type AB
Type O
Genotype(s)
IAIA or IAi
B
B
B
I I or I i
A
B
I I
ii
Polygenic (Many genes)
Many traits come in many forms
– Height, Skin color, Hair color, Eye
color
These are controlled by several genes
Environmental Factors
Some genes are affected by the environment
Himalayan Rabbit
Chromosome Number
Each species has a specific number of
chromosomes.
Humans – 46
House fly – 12
Chimpanzee – 48
Horse – 64
Dog – 78
If the species reproduces sexually, the number is
even.
Humans chromosomes.
Humans have 23 different chromosomes
2 of each = 46 total
A cell that has all 46 (or 2 of each) is diploid (di=2)
Gametes, sperm or egg cells only have 1 of each or 23
chromosomes.
These are haploid cells
Sperm (23) + Egg (23) = Zygote (46)
Zygote is the fertilized egg
Meiosis – Forms gametes
Gametes are specialized haploid sex cells
Sperm and Egg cells
In meiosis a diploid cell divides twice producing
4 cells
Human Diploid cell (46 chromosomes)
Meiosis goes through the same steps twice
P1M1A1T1P2M2A2T2
Meiosis I
Meiosis I separates homologous chromosomes
1 from 1, 2 from 2 etc
Homologous chromosomes – chromosomes that
have the same information
Prophase I
Nuclear envelope dissolves
Homologous chromosomes pair
up to form a tetrad (four)
Spindle fibers form and attach to
the tetrad
Metaphase I
Tetrads are lined up in the center of the cell
Anaphase I
The homologous pairs are separated
Telophase I and cytokinesis
The nuclear membranes reform
Meiosis II
Meiosis II is just like Mitosis, but
chromosome number has been cut in half.
P2M2A2T2
Mitosis vs Meiosis
Recombination
During Prophase I
homologous
chromosomes can
exchange pieces
This creates new
combinations of genes