A Family Tree
To understand how traits are passed on , a pedigree diagram showing the
family relationships, is used. In a pedigree, a circle =‘s a female, a square
=‘s a male. A filled-in circle or square shows that the individual has the
trait. The horizontal line that connects a circle and a square =‘s a marriage.
The vertical line(s) and brackets below are the child(ren) of that couple.
1. This pedigree shows the inheritance of attached ear lobes.
Which parent has attached ear lobes?
2. How many children do the parents have? Which child has
attached ear lobes?
3. Which child is married? Does this child’s spouse have
attached ear lobes? Do any of this child’s children have
attached ear lobes?
14–1 Human Heredity
A. Human Chromosomes
1. Karyotype
a. autosomes
b. sex chromosomes
Making a Karyotype
activity
http://learn.genetics.utah.edu/u
nits/disorders/karyotype/kar
yotype.cfm
B. Human Traits- Click to see pedigree chart
C. Human Genes
1. Blood Group Genes Click to see slide
2. Recessive Alleles
Click here for concept map
3. Dominant Alleles
of these 3 alleles
4. Codominant Alleles
D. From Gene to Molecule
1. Cystic Fibrosis Click here for slide
2. Sickle Cell Disease Click here for slide
Click button if you want to go
directly to the next section
A circle
represents
a female.
A horizontal line
connecting a male
and female
represents a
marriage.
A half-shaded
circle or square
indicates that a
person is a
carrier of the
trait.
A completely
shaded circle
or square
indicates that
a person
expresses the
trait.
A square
represents a
male.
Click here to
return to
previous
slide
A vertical line
and a bracket
connect the
parents to their
children.
A circle or
square that
is not
shaded
indicates
that a
person
neither
expresses
the trait nor
is a carrier
of the trait.
Phenotype
(Blood Type
Genotype
Safe Transfusions
Antigen on
Red Blood Cell
To
Click here to return to outline
From
Autosomal
Disorders
Concept Map
Click to
return to
outline
caused by
Recessive
alleles
Albinism
Galactosemia
Dominant alleles
TaySachs
disease
Codominant alleles
Huntington’s
Sickle
cell
AchondroCystic
fibrosis
Phenylketonuria
plasia
Hypercholesterolemia
Chromosome # 7
Normal CFTR is a chloride
ion channel in cell
membranes. Abnormal
CFTR cannot be transported
to the cell membrane.
The most common allele
that causes cystic
fibrosis is missing 3 DNA
bases. As a result, the
amino acid
phenylalanine is missing
from the CFTR protein.
Click here
to return to
outline
The cells in the person’s
airways are unable to
transport chloride ions. As
a result, the airways
become clogged with a
thick mucus.
20% of African Americans
are carriers for sickle cell
disease. Children who
receive a recessive gene
from each parent can
become blind. Arms and
legs can become paralyzed
or even die. Strokes and
heart attacks are common.
Treatments are available to
decrease the complications
of this disease but there is
no cure.
Many African Americans
will ask to be tested to see
if they have one of these
genes in their
chromosomes.
Button takes you to
next section.
Gender Benders
You may remember that in humans, the sperm cells may
carry an X chromosome or a Y chromosome, while egg
cells have only X chromosomes. Sometimes, errors
during meiosis in one of the parents produce offspring
with an abnormal number of sex chromosomes.
1. On a sheet of paper, construct a Punnett square for the following
cross:
XX x XY.
Fill in the Punnett square. What does the Punnett square represent?
According to the Punnett square, what percentage of the offspring from
this genetic cross will be males? What percentage will be females?
2. On a sheet of paper, construct a Punnett square for the following
cross:
XXX x XY.
Fill in the Punnett square. How is this Punnett square different from the
first one you constructed? What might have caused this difference?
3. How do the offspring in the two Punnett squares differ?
14–2 Human Chromosomes
A. Human Genes and Chromosomes
Click for nondisjunction slide
B. Sex-Linked Genes
1. Colorblindness Click for punnett square slide
2. Hemophilia
http://www.ygyh.org/hemo/whatisit.htm
3. Duchene Muscular Dystrophy
http://www.ygyh.org/dmd/whatisit.htm
C. X-Chromosome Inactivation
The coloration of
tortoiseshell cats is a
visible manifestation of Xinactivation. The "black"
and "orange" alleles of a fur
coloration gene reside on
the X chromosome. For any
given patch of fur, the
inactivation of an X
chromosome that carries
one gene results in the fur
color of the other, active
gene.
Click to go to next part of outline
D. Chromosomal Disorders
1. Down Syndrome- site has interactive slide
show of how this syndrome occurs
http://learn.genetics.utah.edu/units/disorders/karyotype/downsyndro
me.cfm
2. Sex Chromosome Disorders
A. Turner’s site has interactive slide show of how
this syndrome occurs
http://learn.genetics.utah.edu/units/disorders/karyotype/turnersyndro
me.cfm
B. Kleinfelter’s site has interactive slide show
of how this syndrome occurs
http://learn.genetics.utah.edu/units/disorders/karyotype/klinefelter.cf
m
Click to go to next part of outline
Homologous
chromosomes fail
to separate
Homologous
chromosomes fail
to separate
Meiosis I:
Nondisjunction
Homologous
chromosomes fail
to separate
Meiosis I:
Nondisjunction
Click to return to outline.
Meiosis II
Father
(normal vision)
Normal
Colorblind vision
Male
Female
Daughter
(normal vision)
Mother
(carrier)
Click to
return to
outline
Normal
Colorblind vision
Male
Female
Mother
(carrier)
Father
(normal vision)
14–3-Human Molecular Genetics
A. Human DNA Analysis
1. Testing for Alleles
Click for next
part of outline
http://www.accessexcellence.org/AE/AEPC/NIH/gene09
.html
Different types of genetic
tests are used to hunt for
abnormalities in whole
chromosomes, in short
stretches of DNA within or
near genes, and in the
protein products of genes.
2. DNA Fingerprinting-an on line interactive
lab (takes 45 minutes, may wish to assign for home)
http://www.pbs.org/wgbh/nova/sheppard/analyze.html
DNA Game- quick look at how DNA fingerprinting can
solve a crime
http://library.thinkquest.org/C0125833/english/whodunit.php
Click to go to next slide
B. The Human Genome Project-This link is to
the HGP home page
http://www.ornl.gov/sci/techresources/Human_Genome/ho
me.shtml
1. Rapid Sequencing
2. Searching for Genes Click to go to slide
3. A Breakthrough for Everyone –
public knowledge and access. See above
link.
Click to continue outline
Sequences can locate
genes.
Intron
Click to return to
outline
Start codon
Promoter
Insulin gene
Stop codon
C. Gene
Therapy
Gene therapy
using a virus. A
new gene is
inserted into a
virus, which is
used to introduce
the modified DNA
into a human cell.
If the treatment is
successful, the
new gene will
make a functional
protein.
D. Ethical Issues in Human Genetics