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4.3.12 – Deduce the genotypes and phenotypes of
individuals in pedigree charts.
Studying humans requires alternative
methods.
 Human geneticists use

.

Human
are
Label:
4.3.12 – Deduce the genotypes and phenotypes of
individuals in pedigree charts.
Human Pedigree tracing a dominant trait
Human Pedigree tracing a recessive trait
Human Pedigree tracing a sex-linked trait
4.1.3 – Define gene mutation.
4.1.4 – Explain the consequence of a base substitution
mutation in relation the process of transcription and
translation, using the example of sickle-cell anemia.
Human genetic disorders result from
.

Gene Mutations –
1.

Hundreds of human genetic disorders involve
defects caused by mutations of

Disorders caused by mutated
alleles: PKU, cystic fibrosis, sickle cell anemia,
Tay-Sachs disease
4.1.4 – Explain the consequence of a base substitution
mutation in relation the process of transcription and
translation, using the example of sickle-cell anemia.

Sickle Cell Anemia is the result of a gene mutation
called a
 Hemoglobin is found in your
.
 Each hemoglobin molecule is made up of
(-hemoglobin) and
(-hemoglobin)
 The mutation producing sickle cell hemoglobin is in
the gene for -hemoglobin.
4.2.4 – Explain that non-disjunction can lead to
changes in chromosome number, illustrated by
reference to Down syndrome (trisomy 21).
2. Chromosome mutations –
•
Results from nondisjunction –
Extra chromosomes
Missing chromosomes
4.2.4 – Explain that non-disjunction can lead to
changes in chromosome number, illustrated by
reference to Down syndrome (trisomy 21).
 Fertilization
may result in trisomy or
monosomy
 Trisomy –
○ Example: Down’s Syndrome (Trisomy 21);
Klinefelter’s Syndrome (XXY)
○ Trisomy 21 - Down Syndrome
 3 copies of chromosome 21
 Mild to severe mental retardation
 Many lead productive lives
○ Klinefelter Syndrom (XXY
condition)
 Most from non-disjunction in
mother
 Tall, some mental slowness
 Poor male sex organ
development; breast
development;
usually sterile
Personal story
4.2.4 – Explain that non-disjunction can lead to
changes in chromosome number, illustrated by
reference to Down syndrome (trisomy 21).
 Monosomy –
○ Example: Turner Syndrome (XO)
○ Turner Syndrome
 one too few chromosomes (XO)
 Sterile (cannot have children), shorter than
average, heart defects, premature aging, shorter
lives
○ YO = LETHAL
 No babies have been
reported being born
without an X
Nondisjunction of
sex chromosomes
 Some
genetic disorders
are caused by
• Examples include:
Hemophilia, Color blindness,
and Duchenne muscular
dystrophy
4.2.5 – State that, in karyotyping chromosomes are
arranged in pairs according to their size and structure.

Karyotype - refers to both the chromosome
composition of an individual and to a
photomicrograph showing the chromosomes
 Uses:
○ To detect genetic disorders
○ For genetic counseling of prospective parents
4.2.5 – State that, in karyotyping chromosomes are
arranged in pairs according to their size and structure.
 Process:
○ Fetal cells, cells from bone marrow, skin, or blood
are cultured and then treated with colchicine
(arrests the cell in metaphase)
○ Chromosomes are
4.2.6 – State that karyotyping is performed using cells
collected by chorionic villus sampling or
amniocentesis, for pre-natal diagnosis of chromosome
abnormalities.

Many birth defects and genetic abnormalities
can be detected before birth
 .
4.2.6 – State that karyotyping is performed using cells
collected by chorionic villus sampling or
amniocentesis, for pre-natal diagnosis of chromosome
abnormalities.