Transcript SEX-LINKED TRAITS

Human Genetics:
Patterns of Inheritance for
Human Traits
Chapter 14
Bell Work
3-29-2016
1. Define sex-linked traits.
2. ___ are the female chromosomes and ___ are the
male.
3. How are linkage and gene maps related?
LT 31 I can explain sex-linked patterns of
inheritance.
What is the LT?
Agenda
1. BW / LT / Study Island
2. Vocab & ????
3. Discussion of Sex – Linked Traits
4. Video
5. Worksheet Practice
Vocabulary and ?????
1.What is meant by gene linkage?
2. Define: multiple alleles, polygenic traits, sex linked traits, linkage
group, an state and example of each
3. Who is Thomas Morgan?
a. What did he study?
b. Describe his experiment.
4. Why are fruit flies ideal for studying genetics?
5. Describe how gene location on a chromosome affects the
appearance of the trait and the assortment.
6. How are linkage and gene maps related?
7. What structures assort independently?
8. What is the allele combination for a male? Female?
9. Explain the inheritance of sex chromosomes in mammals.
10. Research how the following are sex linked traits; hemophilia,
muscular dystrophy, fragile-X syndrome, red-green color blindness
We will be discussing 5 Patterns of
Inheritance for Human Traits
1. Single Allele Dominant
2. Single Allele Recessive
3. Sex Linked (X-Linked)
4. Multiple Alleles
5. Polygenic Traits
What are autosomal traits?
• Karyotype
– an individual's collection of chromosomes
Single Allele Genes
Regular traits that are either determined by a dominant or
recessive allele on an autosome
1. Autosomal Dominant examples:
a. Huntington’s Disease (Chromosome 4, 22)
b. Achondroplasia (dwarfisim) (Chromosome 21)
c. Polydactyly (extra fingers and toes) (Chromosome 7)
d. Down Syndrome (Chromosome 21)
2. Autosomal Recessive examples:
a. Albinism (Chromosome 11)
b. Cystic Fibrosis (Chromosome 7)
c. Sickle Cell Anemia (Chromosome 11)
1. Dominant Allele Disorders
Huntington’s Disease (HD)
 Results in loss of muscle
control and mental
deterioration
 No signs are shown until 30’s
 Brain degeneration
 Treatment: No cure, but drug
treatments are available to
help manage symptoms.
1. Dominant Allele Disorders
Achondroplasia
 Dwarfism
 Person grows no
taller than 4’4
1. Dominant Allele Disorders
Polydactyly
 The presence of more
than the normal
number of fingers or
toes.
 Can usually be
corrected by surgery.
2. Recessive Allele Disorders
Albinism
 Lack of pigment in skin,
hair, and eyes
 Mutation in one of several
genes which provide the
instructions for producing
one of several proteins in
charge of making melanin.
2. Recessive Allele Disorders
Cystic Fibrosis (CF)
 Caused by recessive
allele on chromosome 7
 Small genetic change
(removes one Amino
Acid)  changes protein
 Results in: Excess mucus
in the lungs, liver and
digestive tract, gets
infection easily, and early
death unless treated.
2. Recessive Allele Disorders
Sickle Cell Disease
 Red blood cells are
bent and twisted
 Get stuck in capillaries
 damage tissues
 Results in weakness,
damage to brain and
heart
SEX-LINKED
and
SEX
INFLUENCED
TRAITS
What did you learn about
Thomas Morgan’s research?
?????’s he wanted answers to…
What were inherited factors?
Where were they located?
How were they passed from one generation to the
next?
Chromosomal theory of
inheritance
Genes are located on chromosomes like beads
on a string, and that some genes are linked
*meaning they are on the same
chromosome and always inherited together
Sex-linked Traits
Example: Eye color in fruit flies
Sex Chromosomes
fruit fly
eye color
XX chromosome - female
XY chromosome - male
copyright cmassengale
17
Sex-linked Trait Problem
• Example: Eye color in fruit flies
• (red-eyed male) x (white-eyed female)
XRY
x
XrXr
• Remember: the Y chromosome in males
does not carry an allele for the trait.
• RR = red eyed
Xr
Xr
• Rr = red eyed
• rr = white eyed
• XY = male
XR
• XX = female
50% red eyed
female
50% white eyed
male
Y
18
What is the difference between an
Autosome and a Sex-chromosome?
• Autosomes are the first 22
homologous pairs of human
chromosomes that do not
influence the sex of an
individual.
• Sex Chromosomes are the 23rd
pair of chromosomes that
determine the sex of an
individual.
SEX DETERMINATION
XX = female
Xy = male
Who decides?
X
X
X
Mom can give X
X
Dad can give X or y
y Xy
Dads determine sex of babies.
If dad gives X with mom’s X = girl
If dad give y with mom’s X = boy
X
XX
Xy
Bell Work
3-30-2016
EOC in 43 DAYS!!!
1. What is a karyotype?
2. Chromosomes ____ are all autosomes and ___
are sex chromosomes.
3. Who is Thomas Morgan and describe his
research?
LT 31 I can explain sex-linked patterns of
inheritance.
Bell Work
3-31-2016
EOC in 42 DAYS!!!
1. Consider your knowledge of mitosis and meiosis. How do
these processes relate to an organisms karyotype ?
2. Set up a Punnett cross to determine the offspring
phenotype ratio for parents that are XcY and XCXc in
which normal eyesight (C) is dominant to color blindness
(c).
3. How many autosomal chromosomes can you expect to
find on a normal organisms karyotype?
4. Explain how you can examine a karyotype to determine if
the organism is male or female.
LT 31 I can explain sex-linked patterns of inheritance.
What is the LT?
Agenda
1. BW / LT
2. Review
3. Crazy TraitsZ
Making a BABY!
When directed groups will get the Crazy Traits from
the counter.
1.
2.
You will make all predictions first using the guide sheet.
Toss the red and black (X, Y) chips to determine the genotype and phenotype of
the offspring. Chart
3. Toss the green and blue chips with the “T” to determine the traits of the parents.
Chart as you do each one.
4. Complete a Punnett square using the parents traits to determine the genotype of
offspring.
5. Roll the die to determine which square to use (only use #1-4). Chart genotype
6. Using the “Key” on the back to determine the phenotype of the offspring.
7. Create your BABY.
8. Toss one penny at a time to determine if the parents are colorblind or normal.
Chart
9. Complete a Punnett square choose the phenotype and genotype for the offspring.
10. Answer questions
Bell Work
3-30-2016
EOC in 43 DAYS!!!
1. What is a karyotype?
2. Chromosomes ____ are all autosomes and ___
are sex chromosomes.
3. Who is Thomas Morgan and describe his
research?
LT 31 I can explain sex-linked patterns of
inheritance.
What is the LT?
Agenda
1. BW / LT
2. Amoeba WKST
3. (Groups) Internet
http://www.k-state.edu/biology/pob/genetics/xlinked.htm
4. Crazy Traits
Bell Work
4-01-2016
EOC in 41 DAYS!!!
Draw a mind map demonstrating the relationship
between homologous chromosomes, sex
chromosomes, mitosis, meiosis, karyotype, gene map,
genes, and DNA beginning with the word nucleus.
Be prepared to share.
LT 31 I can explain sex-linked patterns of inheritance.
What is the LT?
Agenda
1. BW / LT
2. EOC Study Guide
3. Crazy Traits
Who decides?
X
X
X
Mom can give X
X
Dad can give X or y
y Xy
Dads determine sex of babies.
If dad gives X with mom’s X = girl
If dad give y with mom’s X = boy
X
XX
Xy
SEX CHROMOSOMES
CAN CARRY OTHER
GENES TOO
SEX LINKED TRAITS
= ___________________
show up
in different % in males and
females because they move with
the sex chromosomes
SEX LINKED TRAITS
Sex chromosomes can
carry other genes
Y-LINKED GENES:
Genes carried on Y chromosome
EX:
Hairy pinna
Y linked
males.
_________genes
only show up in _______
Make a cross with a y-linked gene
Hairy ears is a
Y linked
________________
dominant
________________
trait
H for hairy ears.
Use ______
Use ______
h for recessive normal ears.
H
y
On y chromosome so write it as ________
Make a cross with a y-linked gene
X
X
H
y
XX
X yH
X
XX
X
H
y
ALL GIRLS =
____________
Normal ears
ALL BOYS =
Hairy ears
____________
Sex chromosomes can
carry other genes
X-LINKED GENES:
Genes carried on
the X chromosome
EX: _____________
Hemophilia
_____________
Colorblindness
Duchenne Muscular Dystrophy
_________________________
Make a cross with an X-linked gene
Hemophilia is an
X-linked
________________
recessive
________________
disease
H for normal dominant blood
Use ______
clotting gene.
h
Use ______
for recessive hemophilia gene.
h
X
On X chromosome so write it as ________
Mother
H H
Without hemophilia = X X
H
Without hemophilia = X X
h
h
With hemophilia = X X
Father
H
Without hemophilia = X y
h
With hemophilia = X y
h
CARRIER
Make a cross with an X-linked gene
Colorblindness is an
X-linked
________________
recessive
________________
disease
B for normal dominant color gene
Use ______
b
Use ______
for recessive colorblind gene.
b
X
On X chromosome so write it as ________
Mother
B
B
normal vision = X X
B
normal vision = X X
b
b
colorblind = X X
Father
B
normal vision = X y
b
colorblind = X y
b
CARRIER
SEX LINKED TRAITS show
up
in different % in males and
females because they move with
the sex chromosomes
ONLY show up in males.
Y linked genes ________
more often
X linked recessive genes appear __________
in males than females.
CARRIERS for X linked
Females can be __________
recessive traits.
NEVER BE carriers for X linked
Males can _________
recessive genes. The either have trait OR are
normal.
Bell Work
4-11-2016
EOC in 30 DAYS!!!
1. Define passive and active cellular transport using the terms
diffusion, osmosis, facilitated diffusion, and active
transport and the concept of high to low concentration and
low to high concentration.
2. What is the equation for photosynthesis, and where does it
take place?
3. What is ATP and how does it release energy?
4. Describe 3 forms of evidence for evolution.
5. Describe sex-linked traits.
LT 31 I can explain sex-linked patterns of inheritance.
What is the LT?
Agenda
1. BW / LT
2. Discussion
1. EOC
2. Sex-linked traits
3. Activity
4. Formative Tomorrow
Bell Work
4-12-2016
EOC in 29 DAYS!!!
1. What element do the 4 macromolecules have in common?
2. Compare prokaryote and eukaryotes using the words
nuclear membrane, nuclear material, nucleus,
multicellular, unicellular, one organelle, more organelles,
plants, animals, fungi, protista, and bacteria.
3. Describe the 3 statements for cell theory.
4. Beginning with organelles and ending with organism, what
are the levels of organization.
5.
Make a cross with an sex-linked gene of parents when the
mother is a carrier and the father is normal.
LT 31 I can explain sex-linked patterns of inheritance.
What is the LT?
Agenda
1. BW / LT
2. Discuss assignment
3. Formative
H
X
Carrier Mom X
Normal dad
y
H
H
X X
H
X y
h
H
h
h
X
X
X X
H
X y
GIRLS
1/2 = normal
_______
_______
1/2 = look normal
but are
CARRIERS
BOYS
1/2 = normal
_______
_______
1/2 = hemophilia
Color blindness is sex linked
y
Xb
X
B
X
B
B
X X
b
XBXb
XBy
XBy
GIRLS = _______________
100% carriers
100% normal
BOYS = ________________
HOMOZYGOUS
Normal Mom X
colorblind dad
Bell Work
4-13-2016
EOC in 28 DAYS!!!
1. Compare endocytosis and exocytosis.
2. Draw a diagram demonstrating the effects of concentration
on a cell: hypotonic, hypertonic and isotonic.
3. What is the cellular function of flagella, cilia, and
pseudopodia?
4. Compare the shape and organelles of plant and animal
cells.
5. What is a pedigree?
LT 31 I can explain sex-linked patterns of inheritance.
What is the LT?
Agenda
1. BW / LT / EOC Guide / Study Island
2. Formative
3. Pedigree Activity
What is the difference between an
Autosome and a Sex-chromosome?
Autosomal Traits
• Genes located on Autosomes control
Autosomal traits and disorders.
2 Types of Traits:
• Autosomal Dominant
• Autosomal Recessive
Autosomal Dominant Traits
• If dominant allele is present on the autosome, then the
individual will express the trait.
• A = dominant a = recessive
• What would be the genotype of an individual with an
autosomal dominant trait?
– AA and Aa (Heterozygotes are affected)
• What would be the genotype of an individual without the
autosomal dominant trait?
– aa
Autosomal Recessive Traits
• If dominant allele is present on the autosome, then the
individual will not express the trait. In order to express the
trait, two recessive alleles must be present.
• A = dominant a = recessive
• What would be the genotype of an individual with an
autosomal recessive trait?
– aa
• What would be the genotype of an individual without the
autosomal recessive trait?
– AA or Aa
– Aa – called a Carrier because they carry the recessive allele and can
pass it on to offspring, but they do not express the trait.
Sex-Linked Traits
• Sex-linked traits are produced by genes only on the X
chromosome.
• They can be Dominant or Recessive.
• A = dominant a = recessive
• What would be the genotypes of a male and female that have a Sex-linked
Dominant trait and do not express the trait?
• Expresses Trait:
Male - XA Y
Female - XA XA or XA Xa
• No Expression:
Male - Xa Y
Female - Xa Xa
• What would be the genotypes of a male and female that have a Sex-linked
Recessive trait and do not express the trait?
• Expresses Trait:
Male - Xa Y
Female - Xa Xa
• No Expression:
Male - XA Y
Female - XA XA or XA Xa
(Carrier)
• Most Sex-linked traits are Recessive!
Genetic Counselor Activity
• Imagine that you are a Genetic
Counselor assigned to family to
discuss with them the possibility
of their child inheriting a genetic
disorder.
• You are given the family history and
whether or not the disorder is
Autosomal Dominant or Autosomal
Recessive.
• Draw Punnett Squares to determine
odds of children inheriting the disease
and answer the questions on the
worksheet.
How to Construct a Pedigree?
• A Pedigree is a visual showing the pattern of
inheritance for a trait. (Family tree)
•
•
•
•
Symbols and Rules:
Male =
Female =
Affected =
Unaffected =
Carrier =
Link parents together with a line and then
make a vertical line to connect to offspring.
Autosomal Dominant Pedigree
• Draw a Pedigree showing a cross between
Heterozygous parents that have 2 boys and 2
girls. (Show all possibilities)
Genotypes of Affected and Unaffected:
• AA and Aa = Affected aa = Unaffected
Aa
aa
Aa
Aa
Aa
AA
Autosomal Recessive Pedigree
• Draw a Pedigree showing a cross between
Heterozygous parents that have 2 boys and 2
girls. (Show all possibilities)
Genotypes of Affected and Unaffected:
• AA=Unaffected Aa=Carrier, Unaffected
aa=Affected
Aa
aa
Aa
Aa
Aa
AA
Sex-Linked Recessive Pedigree
• Draw a Pedigree showing a cross between a Red eyed
Male fruit fly and a Carrier Female fruit fly which
have 2 males and 2 females. (Show all possibilities)
Red is dominant to white.
• Genotypes of Parents:
• Male = XR Y Female = XR Xr
XR
Y
XRY
XRX
r
XrY
XRX
XRX
Characteristics of Autosomal Dominant, Autosomal
Recessive, and Sex-linked Recessive Traits
• In groups, analyze your notes on each type of
disorder and examine the pedigrees.
• Come up with rules/characteristics for each
type of Trait.
Autosomal Dominant Traits
• Heterozygotes are affected
• Affected children usually have affected parents.
• Two affected parents can produce an unaffected
child. (Aa x Aa)
• Two unaffected parents will not produce affected
children. (aa x aa)
• Both males and females are affected with equal
frequency.
• Pedigrees show no Carriers.
Autosomal Recessive Traits
• Heterozygotes are Carriers with a normal phenotype.
• Most affected children have normal parents. (Aa x Aa)
• Two affected parents will always produce an affected child.
(aa x aa)
• Two unaffected parents will not produce affected children
unless both are Carriers. (AA x AA, AA x Aa)
• Affected individuals with homozygous unaffected mates will
have unaffected children. (aa x AA)
• Close relatives who reproduce are more likely to have affected
children.
• Both males and females are affected with equal frequency.
• Pedigrees show both male and female carriers.
Sex-Linked Recessive Traits
• More males than females are affected.
• An affected son can have parents who have the
normal phenotype. (XAY x XAXa)
• For a daughter to have the trait, her father must also
have it. Her mother must have it or be a carrier.
(XaY, XaXa, XAXa)
• The trait often skips a generation from the
grandfather to the grandson.
• If a woman has the trait (XaXa), all of her sons will be
affected.
• Pedigrees show only female carriers but no male
carriers.
Examples of Autosomal Dominant Disorders
•
•
•
•
Dwarfism
Polydactyly and Syndactyly
Hypertension
Hereditary Edema
•
Chronic Simple Glaucoma – Drainage system for fluid in the eye does not work and
pressure builds up, leading to damage of the optic nerve which can result in blindness.
Huntington’s Disease – Nervous system degeneration resulting in certain and early death.
Onset in middle age.
Neurofibromatosis – Benign tumors in skin or deeper
Familial Hypercholesterolemia – High blood cholesterol and propensity for heart disease
Progeria – Drastic premature aging, rare, die by age 13. Symptoms include limited growth,
alopecia, small face and jaw, wrinkled skin, atherosclerosis, and cardiovascular problems but
mental development not affected.
•
•
•
•
Examples of Autosomal Recessive Disorders
•
•
•
•
•
Congenital Deafness
Diabetes Mellitus
Sickle Cell anemia
Albinism
Phenylketoneuria (PKU) – Inability to break
down the amino acid phenylalanine. Requires
elimination of this amino acid from the diet or
results in serious mental retardation.
•
Galactosemia – enlarged liver, kidney failure,
brain and eye damage because can’t digest milk
sugar
Cystic Fibrosis – affects mucus and sweat glands,
thick mucus in lungs and digestive tract that
interferes with gas exchange, lethal.
Tay Sachs Disease – Nervous system destruction
due to lack of enzyme needed to break down lipids
necessary for normal brain function. Early onset
and common in Ashkenazi Jews; results in
blindness, seizures, paralysis, and early death.
•
•
Examples of Sex-Linked Recessive Disorders
• Red/Green Colorblindness – Difficulty perceiving differences between
colors (red or green, blue or yellow).
• Hemophilia – Absence of one or more proteins necessary for normal blood
clotting.
• Deafness
• Cataracts – opacity in the lens that can lead to blindness
• Night blindness – (Nyctalopia) rods do not work so that can not see in the
dark
• Glaucoma – pressure in the eye that can lead to optic nerve damage and
blindness
• Duchenne Muscular Dystrophy – progressive weakness and degeneration
of skeletal muscles that control movement due to absence of dystrophin
(protein that maintains muscle integrity). Mainly in boys, onset 3-5 yrs, by
12 years can’t walk, and later needs respirator.
Karyotype Activity
•
Objective: To learn how to construct a
Karyotype and discover different genetic
diseases from a karyotype.
Procedure:
1. Work in groups of 2-3.
2. Construct a karyotype from one smear
3. Use “Information on Chromosome Disorders” to
identify the type of mutation.
4. Answer questions on the handout.
What are Chromosomal Mutations?
•
•
Damage to chromosomes due to physical
or chemical disturbances or errors during
meiosis.
Two Types of Chromosome Mutations:
1. Chromosome Structure
2. Chromosome Number
Problems with Chromosome Structure:
1. Deletion – during cell division, especially meiosis, a piece
of the chromosome breaks off, may be an end piece or a
middle piece (when two breaks in a chromosome occur).
2. Inversion – a segment of the chromosome is turned 180°,
same gene but opposite position
3. Translocation – movement of a chromosome segment
from one chromosome to a non-homologous chromosome
4. Duplication – a doubling of a chromosome segment
because of attaching a broken piec form a homologous
chromosome, or by unequal crossing over.
Problems with Chromosome Number
5. Monosomy – only one of a particular type
of chromosome (2n -1)
6. Trisomy – having three of a particular type
of chromosome (2n + 1)
7. Polyploidy – having more than two sets of
chromosomes; triploids (3n = 3 of each
type of chromosome), tetraploids (4n = 4
of each type of chromosome).
How do you think Chromosomal Mutations
with differing number of chromosomes
develops?
•
•
•
Monosomy and Trisomy due to Nondisjunction – members of
homologous chromosomes do not move apart in Meiosis I or sister
chromatids do not separate during Meiosis II leaves one cell with
too few chromosomes and one cell with too many.
Triploids develop from the fertilization of an abnormal diploid egg,
produced from the nondisjunction of all chromosomes. Tetraploids
develop from the failure of a 2n zygote to divide after replicating
its chromosomes, subsequent mitosis would produce 4n embryo.
Polyploidy is common in the plant kingdom, spontaneous origin of
polyploid individuals plays important role in evolution of plants.
In the animal kingdom, natural occurrence of polyploids is
extremely rare. In general, polyploids are more nearly normal in
appearance than having monosomy or trisomy, which is more
disruptive to have one extra chromosome in a pair.
Human Pedigree
Analysis
Highlight on the Following Chart
Clues for Autosomal Inheritance
Recessive
Dominant
Clues for Sex-linked Inheritance
Recessive
Draw the Following Chart
Clues for Autosomal Inheritance
Recessive
Dominant
•
individual expressing trait • every affected person has at
has 2 normal parents
least one affected parent
•
two affected parents can • each generation will have
not have an unaffected
affected individuals
child
Clues for Sex-linked Inheritance
Recessive
•
no father-to-son
transmission
•
predominantly males
affected
•
trait may skip generations
INTERPRETING A PEDIGREE
CHART
• Determine whether the disorder is
dominant or recessive.
• If the disorder is dominant, one of
the parents must have the disorder.
• If the disorder is recessive, neither
parent has to have the disorder
because they can be heterozygous.
Rules of Inheritance Autosomal Recessive
•Appears in both sexes with equal frequency
• Trait tend to skip generations
• Affected offspring are usually born to unaffected
parents
• When both parents are hetrozygout, approx. 1/4 of
the progeny will be affected
• Appears more frequently among the children of
consanguine marriages
Rules of Inheritance Autosomal Dominant
• Appears in both sexes with equal frequency
• Both sexes transmit the trait to their offspring
• Does not skip generations
• Affected offspring must have an affected parent unless they
posses a new mutation
• When one parent is affected (het.) and the other parent is
unaffected, approx. 1/2 of the offspring will be affected
• Unaffected parents do not transmit the trait
Rules of Inheritance X-Linked Dominant
Both males and females are affected; often more females than
males are affected
• Does not skip generations.
• Affected sons must have an affected mother;
• affected daughters must have either an affected mother or an
affected father
• Affected fathers will pass the trait on to all their daughters
• Affected mothers if heterozygous will pass the trait on to 1/2
of their sons and 1/2 of their daughters
Rules of Inheritance X-Linked Recessive
• More males than females are affected
• Affected sons are usually born to
unaffected mothers, thus the trait skips
generations
• Approximately 1/2 of carrier mothers’
sons are affected
• It is never passed from father to son
• All daughters of affected fathers are
carriers
Bell Work
1.
2.
3.
4.
5.
4-14-2016
EOC
in
27
DAYS!!!
Define homeostasis and state and example within the
body.
Define aerobic and anaerobic respiration. Decide how
the 3 stages to cellular respiration fit into the two
categories.
In which organelle does aerobic respiration take place?
How do pinocytosis, phagocytosis, and diffusion relate?
What would be the genotype of an individual with an
autosomal recessive trait?
LT 31 I can construct a pedigree chart.
What is the LT?
Agenda
1. BW / LT / Study Island
2. Pedigree Assignment
3. Additional practice
4. Kahoot
Bell Work
4-19-2016
EOC in 22 DAYS!!! (Study guide on your desk)
1. Describe where lactic acid fermentation and
alcoholic fermentation take place.
2. Compare cellular respiration and photosynthesis
with four facts each.
3. What is the function of enzymes? Draw an enzyme
labeling the active site, enzyme and substrate.
4. Construct a pedigree demonstrating 4 generations.
LT 31 I can construct a pedigree chart.
Bell Work
4-19-2016
EOC in 22 DAYS!!! (Study guide on your desk)
1. Compare asexual and sexual reproduction using the terms
mitosis, meiosis, unicellular and multicellular organisms,
haploid, diploid, genetically identical, genetic variation,
2n, n, large number of offspring, low number of offspring,
gametes, and 2 stages of cell division.
2. What happens during cell division?
3. What are the phases of cell cycle? Interphase? Mitosis?
4. What are the results of cytokinesis?
LT 33 I can describe how common genetic disorders
are inherited.
What is the LT?
Agenda
1. BW / LT
2. Review Pedigree Assignment
3. Human Genome Project Cloze
4. Quizlet Live
Human Genome Project
Science of the human genome
• Imagine a world in which we will be able to
treat diseases by altering our very genes‚
giving us new ones if ours are non-functional,
changing bad genes for good ones.
• For the first time in our existence, we are
closer to understanding just what we are. We
now have the tools to make the whole world
better through science ‚
Genetic Disorders
What are monogenic and
chromosomal disorders?
Polygenic traits: influenced by
multiple genes.
Monogene traits: mainly
influenced by single genes.
Mutations
• Gene mutations can be either inherited from a
parent or acquired.
• A hereditary mutation is a mistake that is
present in the DNA of virtually all body cells.
•
• Hereditary mutations are also called germ line
mutations because the gene change exists in
the reproductive cells and can be passed from
generation to generation, from parent to
newborn.
– Mutation is copied every time body cells divide
• Mutations occur all the time in every cell in the
body.
• Each cell, however, has the remarkable ability to
recognize mistakes and fix them before it passes
them along to its descendants. But a cell's DNA
repair mechanisms can fail, or be overwhelmed, or
become less efficient with age. Over time, mistakes
can accumulate.
Down’s Syndrome
• Caused by nondisjunction of the
21st chromosome.
• This means that the
individual has a
trisomy (3 – 2lst
chromosomes).
Down’s Syndrome
or Trisomy 21
Symptoms of Down Syndrome
•
•
•
•
•
•
Upward slant to eyes.
Small ears that fold over at the top.
Small, flattened nose.
Small mouth, making tongue appear large.
Short neck.
Small hands with short fingers.
Symptoms of Down Syndrome
•
•
•
•
•
•
Low muscle tone.
Single deep crease across center of palm.
Looseness of joints.
Small skin folds at the inner corners of the eyes.
Excessive space between first and second toe.
In addition, down syndrome always involves some
degree of mental retardation, from mild to severe.
In most cases, the mental retardation is mild to
moderate.
Turner’s
• Turner syndrome is associated
with underdeveloped ovaries, short
stature, and is only in women.
• Bull neck, and broad chest.
Individuals are sterile, and lack
expected secondary sexual
characteristics.
• Mental retardation typically not
evident.
• Chromosomal or monogenic
Turner’s Syndrome
Sickle Cell Anemia
• An inherited, chronic
disease in which the red
blood cells, normally
disc-shaped, become
crescent shaped. As a
result, they function
abnormally and cause
small blood clots. These
clots give rise to
recurrent painful
episodes called "sickle
cell pain crises".
Sickle Cell
• Sickle cell disease is most commonly
found in African American
populations. This disease was discovered
over 80 years ago, but has not been given
the attention it deserves.
Cystic Fibrosis (CF)
• Monogenic
• Cause: deletion of only 3 bases on
chromosome 7
• Fluid in lungs, potential respiratory failure
• Common among Caucasians…1 in 20 are
carriers
– Therefore is it dominant or recessive?
Hemophilia, the royal disease
• Hemophilia is the oldest
known hereditary bleeding
disorder.
• Caused by a recessive
gene on the X
chromosome.
• There are about 20,000
hemophilia patients in the
United States.
• One can bleed to death
with small cuts.
• The severity of
hemophilia is related to
the amount of the clotting
factor in the blood. About
70% of hemophilia
patients have less than one
percent of the normal
amount and, thus, have
severe hemophilia.
X-linked Inheritance pedigree chart
Huntington’s Disease
• Huntington's disease (HD)
is an inherited,
degenerative brain
disorder which results in
an eventual loss of both
mental and physical
control. The disease is
also known as
Huntington's chorea.
Chorea means "dance-like
movements" and refers to
the uncontrolled motions
often associated with the
disease.
Huntington’s
• Looking back at the
pedigree chart is
Huntington’s dominant or
recessive?
• Scientists have discovered
that the abnormal protein
produced by the
Huntington's disease gene,
which contains an elongated
stretch of amino acids
called glutamines, binds
more tightly to HAP-1 than
the normal protein does.
Diabetes
• Disease in which the body does
not produce or properly use insulin.
– Insulin is a hormone that is needed to convert
sugar, starches, and other food into energy
needed for daily life.
• Genetic mutation can lead to Type 1
diabetes, but no one sure if relative to a
specific gene
Diabetes
• Type 1 reveals itself in childhood, Type 2 can be made
worse from excessive lifestyle
• Warning signs
–
–
–
–
–
Extreme thirst
Blurry vision from time to time
Frequent urination
Unusual fatigue or drowsiness
Unexplained weight loss
– Diabetes is the leading cause of kidney failure,
blindness, and amputation in adults, and can
also lead to heart disease.
Color Blindness
• Cause: x-linked
recessive
• 1/10 males have,
1/100 females have.
Why the difference?
• Individuals are unable
to distinguish shades
of red-green.
• Are you color blind?
Albinism
• Patients are unable to produce skin or eye
pigments, and thus are light-sensitive
• Autosomal recessive
– Therefore, is it monogenic or chromosomal?
Bell Work
4-20-2016
EOC in 21 DAYS!!! (Study guide on your desk)
1. What are the results of the first meiosis
division? Second meiosis division?
2. Explain Mendel's laws of heredity: law of
dominance, law of segregation and law of
independent of assortment.
3. Describe 3 forms of evidence for
evolution.
• Study for the Formative
What is the LT?
Agenda
1. BW / LT
2. Formative
3. Study Island
4. Quizlet
Achondroplasia (a.k.a. dwarfism)
• Monogenic, autosomal
– Carriers express genes, therefore, is it dominant
or recessive?
– There is also a disease called gigantism (Andre
the Giant)
Phenylketonuria or PKU
People with PKU cannot consume any product that
contains aspartame.
PKU is a metabolic disorder that results when the
PKU gene is inherited from both parents
(recessive or dominant? Monogenic or
chromosomal?)
Caused by a deficiency of an enzyme which is
necessary for proper metabolism of an amino acid
called phenylalanine.
PKU
• Phenylalanine is an essential amino acid
and is found in nearly all foods which
contain protein, dairy products, nuts, beans,
tofu… etc.
• A low protein diet must be followed.
• Brain damage can result if the diet is not
followed causing mental retardation…and
mousy body odor (phenylacetic acid is in
sweat).
PKU
Phenylalanine.
Free diet
•
ALS
(Amyotrophic Lateral Sclerosis, or
Lou Gehrig’s disease)
• the disease strikes people between the ages
of 40 and 70, and as many as 30,000
Americans have the disease at any given
time
• This monogenic mutation is believed to
make a defective protein that is toxic to
motor nerve cells.
• A common first symptom is a painless
weakness in a hand, foot, arm or leg, other
early symptoms include speech swallowing
or walking difficulty
Adenoleukodystrophy
• ALD) is a rare, inherited
metabolic disorder that
afflicts the young boy
Lorenzo Odone, whose story
is told in the 1993 film
'Lorenzo's oil'. In this disease
the fatty covering (myelin
sheath) on nerve fibers in
the brain is lost, and the
adrenal gland degenerates,
leading to progressive
neurological disability and
death.
Lorenzo’s Oil
•
Their invention, Lorenzo's Oil, has been adopted as the therapy of choice for ALD by
major neurological institutes the world over.
Lorenzo Odone
• The oil came too
late to stop his son
from developing the
symptoms must be
hard to bear.
Lorenzo lost most of
his bodily functions
and has been
bedridden for 18
years.
The very tragic disease…
hairy ears
Y-linked trait, which are
rare
• symptoms…hairy ears
• Only 1 cure known….
For each of the pedigrees below, identify
the mode of inheritance and provide at
least 2 reasons for your choice.
• Autosomal recessive
• Parents and grandparents have normal phenotype
• Both males and females affected
Autosomal Recessive
• Parents, grand parents, and great-grandparents
have normal phenotype
• Inbred line promotes expression of recessive trait
Sex-linked Recessive
• Males only
• Trait skips generations
Autosomal Dominant
• Each generation has the disease
• Each individual has an affected parent
Autosomal Recessive
a) Aa
b) Aa
c) Aa
d) Aa or AA
• This is a pedigree for an inherited lung disease.
Provide the genotypes of each of the individuals
marked with lower case letters.
Autsomal Dominant
a) Aa
b) Aa
c) Aa
d) Aa
e) Aa or AA
• This is a pedigree for an inherited brain disease.
Provide the genotypes of each of the individuals
marked with lower case letters.
Use the pedigree for Trait A to determine
the genetic basis of this trait.
• Does a dominant or recessive allele produce
this trait? Explain
Is it autosomal or sex-linked?
Explain.
• Which progeny assures that the trait is
autosomal?
What are the genotypes of all of the
individuals in the pedigree?
SEX INFLUENCED
TRAITS
not carried on sex
Genes ___________
chromosomes BUT affected by
____________
sex hormones of individual with
gene
Male Pattern Baldness
Autosomal
dominant gene
YOUR SEX CHANGES THE
EXPRESSION OF THE GENE
B is dominant for baldness
b is recessive for not bald
If you are MALE:
BB = BALD
BALD
B=
NOT bald
b=
If you are FEMALE:
BB= BALD
NOT bald
Bb=
NOT bald
bb=
Will they be bald?
Bald = B
XB
XB
XB
XBXB
XBXB
Y
XBy
XBy
Girls: 100% NOT BALD
Autosomal
Dominant gene
Bald dad X
pure non bald mom
Boys: 100% BALD
Will they be bald?
Bald = B
Xb
XB
Xb
XBXb
XbXb
Y
XBy
Xby
Girls: 100% NOT BALD
Autosomal
Dominant gene
NOT BALD dad Xb
NOT BALD mom XBXb
(who had a bald dad)
Boys: 50% BALD
50% NOT BALD
How are genes passed on over
generations?
PEDIGREE
CHART
Males =
Females =
Has trait =
Carrier =
SEX-LINKED
and
SEX
INFLUENCED
TRAITS
SEX DETERMINATION
XX = ___________
Xy = _________
Who decides?
X
Mom can give X
X
Dad can give X or y
y
Dads determine sex of babies.
If dad gives X with mom’s X = girl
If dad give y with mom’s X = boy
X
SEX CHROMOSOMES
CAN CARRY OTHER
GENES TOO
= ___________________
show up
in different % in males and
females because they move with
the sex chromosomes
SEX LINKED TRAITS
Sex chromosomes can
carry other genes
Y-LINKED GENES:
Genes carried on Y chromosome
EX:
Hairy pinna
_________genes only show up in _______
Make a cross with a y-linked gene
Hairy ears is a
________________
________________
trait
Use ______ for hairy ears.
Use ______ for recessive normal ears.
On y chromosome so write it as ________
Make a cross with a y-linked gene
X
X
H
y
X
ALL GIRLS =
____________
ALL BOYS =
____________
Sex chromosomes can
carry other genes
X-LINKED GENES:
Genes carried on
the X chromosome
EX: _____________
_____________
_________________________
Make a cross with an X-linked gene
Hemophilia is an
________________
________________
disease
Use ______ for normal dominant blood
clotting gene.
Use ______ for recessive hemophilia gene.
On X chromosome so write it as ________
Mother
Without hemophilia = X X
Without hemophilia = X X
With hemophilia = X X
Father
Without hemophilia = X y
With hemophilia = X y
Make a cross with an X-linked gene
H
X
H
X
h
X
y
Carrier Mom X
Normal dad
GIRLS
_______ = normal
_______ = look normal
but are
CARRIERS
BOYS
_______ = normal
_______ = hemophilia
Make a cross with an X-linked gene
Colorblindness is an
________________
________________
disease
Use ______ for normal dominant color gene
Use ______ for recessive colorblind gene.
On X chromosome so write it as ________
Mother
normal vision = X X
normal vision = X X
colorblind = X X
Father
normal vision = X y
colorblind = X y
Color blindness is sex linked
Xb
X
B
X
B
y
GIRLS = _______________
BOYS = ________________
HOMOZYGOUS
Normal Mom X
colorblind dad
SEX LINKED TRAITS show
up
in different % in males and
females because they move with
the sex chromosomes
Y linked genes ________ show up in males.
X linked recessive genes appear __________
in males than females.
Females can be __________ for X linked
recessive traits.
Males can _________ carriers for X linked
recessive genes. The either have trait OR are
normal.
SEX INFLUENCED
TRAITS
not carried on sex
Genes ___________
chromosomes BUT affected by
____________
sex hormones of individual with
gene
Male Pattern Baldness
Autosomal
dominant gene
YOUR SEX CHANGES THE
EXPRESSION OF THE GENE
B is dominant for baldness
B’ is recessive for not bald
If you are MALE:
BB =
BB’ =
B’B’ =
If you are FEMALE:
BB=
BB’=
B’B’=
Will they be bald?
Bald = B
BX
B’X
B’X
By
Autosomal
Dominant gene
Bald dad X
pure non bald mom
Will they be bald?
Bald = B
B’X
BX
B’X
B’y
Autosomal
Dominant gene
NOT BALD dad X
NOT BALD mom
(who had a bald dad)
How are genes passed on over
generations?
PEDIGREE
CHART
Males =
Females =
Has trait =
Carrier =