Transcript B. Sex-Linked Disorders

UNIT 9 – THE HUMAN
GENOME
Test Tuesday
2-14-12
(chapter 14)
I. HUMAN GENETICS
(pp. 341-343)
A. Human Somatic Cells
body or __.
diploid
2n
 ________
cells are ______
46 chromosomes,
 Each cell contains ___
23 pairs of chromosomes.
or ___
22 are ____________,
– Of the pairs, ___
homologous
contain the same genes in the same order,
and are called ____________.
autosomes
A. Human Somatic Cells

The 23rd pair of chromosomes are the
____
sex chromosomes.
–
–
Female =___
XX
Male= ___.
XY
B. Human Gametes
n and
Gametes are _______,
haploid or __,
23 chromosomes.
contain ___
egg cells made
 Female gametes are _____
ovaries
in the ___________
in the process of
__________.
meiosis
sperm
 Male gametes are ______cells
made in
the _________
in the process of
testes
meiosis
__________.

B. Human Gametes


Egg cell can only contain an __
X chromosome
Sperm cell produced has a ___%
50 chance of
Y and a ___%
containing a ___
chance of
50
containing an __.
X
– The _____
male determines the sex of the offspring.
C. Analyzing Human Chromosome
Numbers
Nondisjunction - Abnormal
numbers of chromosomes in
gametes
______ result in genetic
number disorders
disorders called ___________.
nondisjunction
 ____________,
which means
______________.
“not coming apart”
1.
C. Analyzing Human Chromosome
Numbers
A chromosome pair fails to separate
anaphase so the gametes
correctly in ________
produced have an abnormal
_____________________.
number of chromosomes
 Number disorders are not inherited;
therefore, they cannot be predicted
Punnett squares
with ________________.

C. Analyzing Human Chromosome
Numbers
2.


Karyotypes –
A karyotype is a photograph of
________________.
chromosome pairs
mitosis and are
Cells are stopped during _________
stained, photographed, and the photograph is
enlarged.
C. Analyzing Human
Chromosome Numbers
The chromosomes are cut out and
homologous pairs in size
arranged in ____________
order, with the ____
sex chromosomes
making up the 23rd pair.
number disorders
 Used to detect _________
gender of an
and to determine the ________
unborn child.

C. Analyzing Human Chromosome
Numbers
They do not detect abnormal _______;
genes
therefore, a normal karyotype does not
normal child!
guarantee a ______
II. HUMAN GENETIC DISORDERS –
NUMBER DISORDERS (pp. 352, 353)
A. Autosomal Number Disorders
 Most are _____.
lethal
 The only autosomal number disorder
that allows survival into adulthood is
Down syndrome
___________________.
Is there a problem with this
karotype
A. Autosomal Number Disorders
Down syndrome
Down syndrome
trisomy 21 because
 known as __________
there are ___
3 chromosomes at the
21st position, instead of ___.
2
____
 Individuals have characteristic facial
features; growth, behavior, and mental
development are all affected
Autosomal Number Disorders
Down syndrome
There is also a
higher risk of
_________
congenital heart
defects.
 The incidence of
babies with Down
syndrome
is
much
o
higher
in ______
older
l
mothers.

Is there a problem with this karyotype?
B. Sex Chromosome Number
Disorders
1. Turner Syndrome
45 XO
 Called ______


because individuals lack
__________________.
2nd sex chromosome
_______,
female typically
______
short in stature,
underdeveloped sexually,
sterile with a normal life
______,
expectancy.
Does this individual have a number
disorder?
B. Sex Chromosome Number
Disorders
2. Klinefelter Syndrome
 Called ________.
47 XXY


Symptoms do not appear
until ________
pubertyat which time
affected _________
males show
poor sexual development
and infertility.
testosterone
Treated with __________.
Normal life expectancy.
III. ANALYSIS OF HUMAN
INHERITANCE
A. Punnett Squares & Multiple Alleles (pp.
345-346)
more than 2
1. multiple alleles; that is, ___________
alleles.
An example of this is ABO blood groups.
3 alleles for this gene. Two of the
There are ____
alleles, A
_______
and B are co-dominant, meaning
they
always show if present. The third allele,
______________
____,
i (o) is recessive, meaning it will only show if
the genotype is ___.
ii
–
. Punnett Squares & Multiple Alleles
(pp. 345-346)

2 alleles for
Each individual inherits ___
this gene, one from _____
mom and one
dad
from ____.
Punnett Squares & Multiple Alleles
(pp. 345-346)
The possibilities for blood group genotypes and
phenotypes are:
Phenotypes
Genotypes
A A
A
I I or I i
Type A blood
_____________
B B
B
Type B blood
_____________
I I or I i
A B
I I
Type AB blood
_____________
ii
Type O blood
_____________

Complete ABO Blood Type Punnetts in Notes
packet
B. Pedigrees

A pedigree is a diagram that follows the
trait through several
inheritance of a single _____
generations of a family.
____________
–
–

squares
Males are represented by ________
circles
Females, by _______.
Individuals with the trait are represented
shaded figures.
with ________
B. Pedigrees
Individuals shown with unshaded figures
_________________.
do not show the trait
parents and children
 Vertical lines connect _______
_______.
spouses or
 Horizontal lines connect _________
siblings
_________.
birth order
 Children are placed in __________,from
left to right
_________.


Complete pedigrees in note packet
IV. INHERITED HUMAN GENETIC
DISORDERS
Gene Mutations
a change in the DNA sequence of the gene
______________________________.
A.

Causes Inherited human genetic disorders
IV. INHERITED HUMAN GENETIC
DISORDERS
B. Types of Inherited Genetic Disorders
1. Autosomal Genetic Disorders – Gene
mutation is on any chromosome other than
sex
chromosomes
________________
2. Sex-Linked Disorders – Mutated gene is on
X chromosome.
the ____
VI. GENETIC DISORDERS - AUTOSOMAL
DISORDERS
(pp. 345-348)



autosomes
Most genes are carried on the ___________,
44
______
chromosomes other than the sex
chromosomes.
autosomal
Most genetic disorders are ___________
disorders.
These disorders affect males and females
equally and are due to _____
gene mutations.
________
Autosomal disorders can be divided into
three groups based on the pattern of
inheritance.
1. Autosomal Recessive
2. Autosomal Co-Dominant
3. Autosomal Dominant
A. Autosomal Recessive
Disorders

1. Albinism – Characterized by failure to
produce pigment, __________.
Affected
melanin
eyes _____,
skin
individuals lack coloration in ______,
and _____.
Very susceptible to ___________.
hair
UV light
Normal
Symptoms appear __________;
_________
life
at birth
expectancy
A. Autosomal
Recessive Disorders
2. Cystic Fibrosis –
Characterized by excess
mucus
production
__________________in
_______,
lungs _________system.
digestive
Symptoms appear just after
birth and include frequent
respiratory infections, poor
nutrition. With treatment,
patients can survive to young
adulthood. Cystic fibrosis is
fatal
the most common _______
genetic disorder in the
United
States among Caucasians.
________

B. Autosomal Co-Dominant
Disorders
Sickle cell anemia is an autosomal cohemoglobin
dominant disorder that affects __________
production.
oxygen to
Hemoglobin is the protein that binds ________
red blood cells.
1.
Sickle cell Anemia

Individuals with the normal genotype, AA,
do not have the sickle cell allele and
produce only normal Hemoglobin.
Sickle cell Anemia
Individuals that are SS produce abnormal
hemoglobin that causes the red blood cells to
“sickle” when oxygen availability is decreased;
–
for example, in high altitudes or during periods of stress.
Sickled RBCs are more fragile, easily destroyed – results in
energy due to decreased _____
ATP production in
lack of ________
cells, blockage of blood vessels, and severe pain.
Shortened life expectancy. Most common inherited disease
African ancestry.
in individuals of ______
Sickle cell Anemia

Heterozygotes (AS) produce both normal and
abnormal hemoglobin and are said to have
________________.
They do not show symptoms of
sickle cell trait
the disorder. In certain areas, individuals with sickle
cell trait have a benefit over individuals that lack the
sickle cell allele because they are resistant to
malaria
_______. Malaria is a serious, sometimes fatal
disease spread by mosquitoes
__________ that affects millions
of people each year in _______.
Africa This increased
malarial resistance has resulted in a very high
incidence of AS individuals. If two heterozygotes
25
marry and have children, they have a ___%
chance
of having a child with sickle cell anemia.
C. Autosomal
Dominant Disorders
1. Huntington’s Disease – Fatal genetic
disorder in which symptoms do not show
30s to 40s
until ______________.
Characterized by
deterioration of _____________.
nervous system
Dwarfism
2. Achondroplasia - ___________
V.
GENETIC DISORDERS - SEXLINKED DISORDERS
A. Sex-Linked Inheritance (pp.350, 351)
 “Sex-linked” if it is located on a sex
X or Y
chromosome (______).

In humans, sex-linked genes are almost
X chromosome.
always located on the larger ___
Y chromosome is much smaller and carries
– The __
only a few genes related to
male sexual development
________________________.
A. Sex-Linked Inheritance
(pp.350, 351)




2 X chromosomes;
Females have __
one
males have ____.
Females will only show recessive traits located on the X
chromosome if they are ________________________.
homozygous recessive
Males will always show a recessive trait located on the
one X
X chromosome because he only has _____
chromosome,
–
genes on the X chromosome will show.
so all _______
males having a much higher
This results in _________
incidence of sex-linked disorders.
A. Sex-Linked Inheritance
1. Genotypes
Genotypes for sex-linked traits are written using the X
and Y chromosomes to show path of inheritance.
–
–
–
For example, male-pattern baldness is a sex-linked
recessive trait. hIf H = normal head of hair and h = baldness,
h h
X
Y
bald male = _____; bald female = _____.
X X
carriers for sex-linked recessive disorders.
Females can be _______
it does not show
A carrier has the defective allele, but ______________.
H h
The genotype of a female carrier is ______.
X X
cannot be carriers for sex-linked traits because
Males _______
their 2nd sex chromosome is the naked
_______!
Y
2. Sex-Linked Punnett Squares
In sex-linked traits, probabilities for male
and female offspring must be calculated
separately because traits are
inherited differently
________________.
If a man with a full head of hair marries a
woman who is heterozygous, what is the
probability they would have a son who would
go bald? A daughter?
B. Sex-Linked Disorders
All of these disorders are sex-linked
recessive
___________________.
1. Color Blindness – Inability to
differentiate and distinguish
colors
___________________.
Results For Ishihara Test(above)
Normal Color Vision
Red-Green Color Blind
Left Right
Left
Right
Spots
Top
25
29
Top
25
Middle
45
56
Middle
Spots 56
8
Bottom Spots Spots
Bottom 6
B. Sex-Linked Disorders
2. Hemophilia – Missing an enzyme required
clotting - results in
for normal blood
____________
uncontrolled bleeding Treated with
_____________________.
blood transfusions, injections of missing
factor.
B. Sex-Linked Disorders
3. Duchenne’s Muscular
Dystrophy – Symptoms
develop at ___________.
3-6 years
Muscles
_____________________
weaken, break down
_, leading to eventual
death. No available
treatment or ______.
cure
__________
Death usually occurs
before adulthood.