Studying humans requires alternative methods.

Human geneticists use .

Human are

4.3.12 – Deduce the genotypes and phenotypes of individuals in pedigree charts.

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

Human genetic disorders result from .

1. Gene Mutations –

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

4.1.3 – 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.

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.

4.1.4 – Explain the consequence of a base substitution mutation in relation the process of transcription and translation, using the example of sickle-cell anemia.

2. Chromosome mutations –

• Results from nondisjunction –

4.2.4 – Explain that non-disjunction can lead to changes in chromosome number, illustrated by reference to Down syndrome (trisomy 21).

Extra chromosomes Missing chromosomes

Fertilization may result in trisomy or monosomyTrisomy –

○ Example: Down’s Syndrome (Trisomy 21); Klinefelter’s Syndrome (XXY)

4.2.4 – Explain that non-disjunction can lead to changes in chromosome number, illustrated by reference to Down syndrome (trisomy 21).

○ Trisomy 21 - Down Syndrome3 copies of chromosome 21Mild to severe mental retardationMany lead productive lives

○ Klinefelter Syndrom (XXY condition)Most from non-disjunction in

mother Tall, some mental slownessPoor male sex organ

development; breast development; usually sterile

Personal story

Monosomy –

○ Example: Turner Syndrome (XO)

4.2.4 – Explain that non-disjunction can lead to changes in chromosome number, illustrated by reference to Down syndrome (trisomy 21).

○ Turner Syndrome one too few chromosomes (XO)Sterile (cannot have children), shorter than

average, heart defects, premature aging, shorter lives

○ YO = LETHALNo 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

Karyotype - refers to both the chromosome composition of an individual and to a photomicrograph showing the chromosomesUses:

○ 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

4.2.5 – State that, in karyotyping chromosomes are arranged in pairs according to their size and structure.

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.

4.2.6 – State that karyotyping is performed using cells collected by chorionic villus sampling or amniocentesis, for pre-natal diagnosis of chromosome abnormalities.