Transcript File - Mrs. Brown @ SCHS

CH 11
Catalyst
• What are the chances of flipping a penny and
having it land on head?
Catalyst
• What are the chances of flipping a penny and
having it land on head?
– There are two possible outcomes for this action:
Heads or Tails
– Answer:
Head
Head or Tail
=
1
2
Catalyst
• What are the chances of flipping a penny and
having it land on head?
Heads
Tails
Catalyst
• What are the chances of flipping two pennies
and having them both land on head?
Catalyst
• What are the chances of flipping two pennies
and having them both land on head?
– There are four possible outcomes for this action:
Heads/Heads, Heads/Tails, Tails/Heads or Tails/Tails
– Answer:
Heads/Heads
Heads/Heads, Heads/Tails, Tails/Heads or Tails/Tails
=
1
4
Catalyst
• What are the chances of flipping two pennies
and having them both land on head?
Heads Tails
Heads
Tails
• Genetics- study of heredity
• Gregor Mendel – Austrian monk who
performed cross fertilization experiments in
1822
• Genetics- study of heredity
• Gregor Mendel – Austrian monk who
performed cross fertilization experiments in
1822
– Result:
• 1. inheritance is determined by factors passed from
one generation to the next
– Gene- section of DNA that codes for a protein
remember: DNA  RNA  protein  trait
• 2. principal of dominance
– Some traits appear whenever the gene is present (dominant)
– Some traits appear when only that gene is present (recessive)
– Some traits are intermediate
during meiosis
Possible
combinations during
Fertilization
Vocab
• Trait- characteristic of an organism
– Ex)
• Phenotype- physical appearance of a trait
– Ex)
• Genotype- alleles for a trait
– Ex)
• Allele- version of a gene
– Ex)
Vocab
• Homozygous genotype- two of the same
alleles for a trait
• AKA “pure-breeding” or “true-breeding”
• Ex) BB or bb
• Heterozygous genotype- two different alleles
for a trait
– AKA hybrid
• Ex) Bb
Smiley Questions
• 1. Explain why were two people flipping pennies
to create one Smiley.
• 2. List any examples of the offspring’s genotype
that is homozygous. List any examples of the
offspring’s genotype that is heterozygous.
• 3. For which traits does your offspring have the
same genotype as it’s mother?
• 4. For which traits does your offspring have the
same phenotype as it’s father?
• 5. Compare the phenotype of your Smiley to
another groups Smiley. Explain why the offspring
have different traits if the parents have the same
genes.
Vocab Matching
1. ___ Father of Genetics
2. ___ What it looks like, physical trait
3. ___ 2 different alleles for the same
trait
4. ___ 2 of the same alleles for the trait
5. ___ the genetic make-up
6. ___ will exhibit the trait only if there
are no dominant traits present
7. ___ sequence of DNA that codes for a
protein and this determines a trait
8. ___ one of a number of different forms
of a gene
9. ___ organism with an allele for a
particular form of a trait will always
exhibit that form of the trait
A.
B.
C.
D.
E.
F.
G.
H.
I.
Gene
Dominant
Heterozygous
Homozygous
Genotype
Allele
Recessive
Gregor Mendel
Phenotype
Remember
meiosis
Vocab
• Monohybrid Cross- Punnet Square to predict
the results of a trait determined by one gene
• Create a Punnet Square to show the possible
offspring for two parents heterozygous for
tongue-rolling.
Tt
Tt
In genetics, what do the T and t
represent?
• The T and t are both alleles (different
versions of a trait).
– The alleles that an individual inherits are the
genotype, the combination of genes that was
inherited.
• For example, for the trait tongue-curling,
there are different variations.
– The trait that is dominant is represented
with the capital letter: H (or T)
• Tongue curling is dominant
– The trait that is recessive is represented
with the lower case letter: h (or t)
• Not curling is recessive
Tt
T
T
Tt
t
Segregation during meiosis
t
alleles in gametes for one parent
T
T
alleles in gametes
for second parent
t
t
Tt
T
T
Tt
t
Segregation during meiosis
t
possible
combinations
during
fertilization
T
T
t
t
possible
combinations
during
fertilization
T
T
t
TT
t
possible
combinations
during
fertilization
T
T
t
TT
t
possible
combinations
during
fertilization
T
T
t
TT
t
Tt
possible
combinations
during
fertilization
T
T
t
TT
t
Tt
possible
combinations
during
fertilization
T
T
TT
t
Tt
t
Tt
possible
combinations
during
fertilization
T
T
TT
t
Tt
t
Tt
possible
combinations
during
fertilization
T
T
TT
t
Tt
t
Tt
possible
combinations
during
fertilization
T
t
T
TT
Tt
t
Tt
tt
possible
combinations
during
fertilization
Which genotype combinations are
homozygous? heterozygous?
TT, Tt, tt
• Homozygous: TT or tt
• Heterozygous: Tt
Ratios, Percentages and Fractions
• 1. Which of the following represent 50%
a. 1:1
b. 1:3
c. 1
d. 1:2:1
• 2. Which ratio is equal to 3/4
a. 1:1
b. 3:1
c. 1
d. 1:2:1
• 3. Which represents 100%
a. 1:1
b. 3:1
c. 1
d. 1:2:1
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
heterozygous
genotype?
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
heterozygous
genotype?
2/4 = 1/2
1:1 ratio or 50%
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
homozygous
genotype?
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
homozygous
genotype?
2/4 = 1/2
1:1 ratio or 50%
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
homozygous
dominant genotype?
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
homozygous
dominant genotype?
1/4
1:3 ratio or 25%
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
homozygous recessive
genotype?
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
homozygous recessive
genotype?
1/4
1:3 ratio or 25%
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
recessive phenotype?
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
recessive phenotype?
1/4
1:3 ratio or 25%
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
dominant phenotype?
T
t
T
TT
Tt
t
Tt
tt
What is the
probability the
offspring will have a
dominant phenotype?
3/4
3:1 ratio or 75%
Pedigrees
• How do you show traits in families?
Pedigrees
Affected female
Affected Male
Unaffected female
Unaffected Male
Carrier
Carrier
Vocab
• P Generation- parent
generation
• F1 Generation- first filial
generation
• F2 Generation- second
filial genration
Pedigree
• Number each generation starting at top: I, II,
III, etc
• Number each person starting in generation I:
1, 2, 3, etc
• Married couples are connected by a horizontal
line.
• Children are shown connected to their parents
by a vertical line.
•
•
•
•
1. Identify a married couple.
2. How many children did they have?
3. Identify the genotypes of all individuals.
4. Create a Punnet square and show the
probability of the unknown (?) inherit the
trait.
• 5. Predict if this is a dominant or recessive
trait. Explain why.
Dominant Trait Hints
• Usually in
every
generation
• If a child has
the trait, at
least one
parent must
show the trait
Recessive Trait Hints
• Can skip
generation
• A child can
have the
trait but the
parents not
show the
trait
(carriers)
Catalyst: make a pedigree
• Lisa and Ashton got married and had three
girls, Cari, Mary, and Terry. It was discovered
that Lisa had muscular dystrophy. Terry
married Perry and had two boys, Pike and
Tike. It was discovered that Terry and Pike had
muscular dystrophy.
Catalyst
• An alien species has been found. Genetists
visiting their home planet have observed the
following:
• Most aliens on the planet have three eyes,
however, when an alien from a family of three
eyes mates with an alien from a family that
just have one eye, all the offspring have one
eye.
• Which is the dominant phenotype?
Dominant and Recessive Traits
• Dominant alleles are able to “mask” recessive
alleles
• Dominant traits are expressed when an
individual is homozygous or heterozygous
– EX) RR or Rr
• Recessive traits are only expressed when an
organism is homozygous
– EX) rr
• If a pea plant with yellow pods and a pea plant
with green pea pods are crossed, all the
offspring are yellow.
Intermediate Traits
• Not all traits are dominant or recessive,
sometimes a blend or mix of traits appears in
the heterozygote.
– Ex) True breeding red flower and true breeding
white flowers are crossed and all the offspring are
pink.
– Ex) True breeding white horses are crossed with
true breeding red horses and all the offspring are
red and white (roan).
Codominant Traits
• The heterozygote shows a mix (BOTH) of
traits
– “Co” = both
– Ex) True breeding white horses are crossed with
true breeding red horses and all the offspring are
red and white (roan).
R
R
• R = red
• R’ = white
R’
R’
Codominant Traits
• The heterozygote shows a mix (BOTH) of
traits
– “Co” = both
– Ex) True breeding white horses are crossed with
true breeding red horses and all the offspring are
red and white (roan).
R
R
• R = red
• R’ = white
R’
RR’
RR’
RR’
RR’
R’
Incomplete Dominance Traits
• The heterozygote shows a blend (combination)
of traits
– Ex) True breeding red flower and true breeding white
flowers are crossed and all the offspring are pink.
• R = red
• R’ = white
R
R’
R’
R
Incomplete Dominance Traits
• The heterozygote shows a blend (combination)
of traits
– Ex) True breeding red flower and true breeding white
flowers are crossed and all the offspring are pink.
• R = red
• R’ = white
R’
R
R
RR’
RR’
RR’
RR’
R’
Catalyst
• An alien species has been found. Genetists visiting their home planet
have observed the following. Six finger aliens that mate with eight
fingered aliens have eight fingered offspring. Aliens with blue skin
that mate with aliens with red skin have purple skin offspring. Aliens
with straight antennae that mate with aliens with curly antennae
have offspring that have both straight and curly antennae.
Match the trait to the pattern of inheritance:
• ___ 1. Finger Number
a. Codominant
• ___ 2. Skin Color
b. Incomplete Dominance
• ___ 3. Antennae Type
c. Dominant and Recessive
Multiple Alleles
• Some genes have more than two
alleles that can be inherited.
– Ex) Blood type
• Type A and B are codominant and O is
recessive
– Alleles:
» IA – A allele
» IB- B allele
» i- O allele
Phenotypes (Blood Type) Genotypes
Type A
IAIA or IAi
Type B
IBIB or IBi
Type AB
I AI B
Type O
ii
Catalyst
• Jane has type O blood. Her brother John has
type B blood and her sister Jordan has type A
blood. What are the genotypes of their
parents?
Sex-linked traits
• Genes that are on sex chromosomes (X or Y)
are inherited differently that traits not on sex
chromosomes (autosomes).
• Review
– XX = female
– XY= male
• Recessive x-linked traits are more common in
males than females.
– Sample
– Examples in humans = hemophilia and color blindness
female
male
XHXH= normal female
XHY= normal male
XHXh= carrier female
XhY = male with hemophilia
Xh Xh = female with hemophilia
• Hemophilia is an X-linked trait. A normal male
person has children with a normal female who
carries the hemophilia allele. What is the probability
their offspring will have hemophilia? What is the
probability their daughters will have hemophilia?
What is the probability their sons will have
hemophilia?
• Color-blindness is an X-linked trait. A male who is
colorblind mates with a normal female. What is the
probability their offspring will have color-blindness?
What is the probability their daughters will have
color-blindness? What is the probability their sons
will have color-blindness?
X-link Pedigree hints
• Skips generations
• More common in males
• Males must have carrier mothers OR mothers
with trait
– Ie. Sons inherit this trait from their moms
Catalyst
• A normal vision pregnant mother is concerned
about having a colorblind son because her
husband is colorblind. No one in the mothers
family has the colorblindness trait. What
would you tell her?
Polygenic Traits
• Traits that are due to interaction of more than
one gene
– Variety of
phenotypes
– Human
examples:
• Hair color
• Eye color
• Skin color
Inheritance Chart
Test Cross
• Cross of homozygous recessive (rr) individual
with a individual with a individual with a
dominant trait (RR or Rr)
• Used to identify the genotype of a individual
with a dominant trait
Karyotype
• Picture of chromosome
– Used to identify sex of unborn child
– Used to identify genetic disorders caused by
nondisjunction
Making a karyotype
– Amniocentesis
• Fetal cells removed from
amniotic fluid of pregnant mother
– Cells stained, picture taken and
chromosomes arranged from largest to smallest
• Identifying sex using
karyotype
– Male: X and Y
chromosome
– Female: XX
chromosomes
• Identifying genetic
disorders caused by
nondisjunction
– Ex) Down’s Syndrome
• Trisomy 21
(3 chromosome 21’s)
Klinefelter's
Syndrome (XXY)
Turner Syndrome
(XO)
O = missing chromosome
Down Syndrome: Trisomy 21
Cri-du-chat:
“meow” when laugh
(deletion mutation
chromosome 5)
• Monosomy X (Turner's syndrome): XO individuals are genetically female,
however, they do not mature sexually during puberty and are sterile. Short stature
and normal intelligence. (98% of these fetuses die before birth)
• 47, XYY males: Individuals are somewhat taller than average and often have
below normal intelligence.
• Klinefelter syndrome: 47, XXY males. Male sex organs; unusually small
testes, sterile. Breast enlargement and other feminine body characteristics. Normal
intelligence.
• Edward's syndrome (trisomy 18): almost every organ system affected
1:10,000 live births. Children with full Trisomy 18 generally do not live more than a
few months.
• Patau syndrome (trisomy 13): serious eye, brain, circulatory defects as well
as cleft palate. 1:5000 live births. Children rarely live more than a few months.
• Down syndrome (trisomy 21): The result of an extra copy of chromosome 21.
Down syndrome affects 1:700 children and alters the child's phenotype either
moderately or severely: characteristic facial features, short stature; heart defects,
susceptibility to respiratory disease, shorter lifespan , prone to developing early
Alzheimer's and leukemia , often sexually underdeveloped and sterile, usually
some degree of mental retardation.
Nondisjunction
• When a homologous
pair (tetrad) does NOT
separate during
anaphase of meiosis
• Result: 1 cell has extra
Chromosome
(trysomy), other cell
has 1 less chromosome
(monosomy)