Human Heredity This section explains what scientists know about human chromosomes, as well as the...
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Transcript of Human Heredity This section explains what scientists know about human chromosomes, as well as the...
Human Heredity
This section explains what scientists know about human chromosomes, as well as the inheritance of certain human traits and disorders.
It also describes how scientists study the inheritance of human traits.
Human Chromosome How do biologists make a karyotype? A karyotype is simply a picture of a
person's chromosomes in mitosis. The chromosomes are isolated in the
WBC, stained, and examined under the microscope.
A picture of the chromosomes is taken through the microscope.
They cut out the chromosomes from the photographs, then group them together in pairs.
Make A Karyotype
Virtual lab: http://learn.genetics.utah.edu/conten
t/chromosomes/karyotype/
http://learn.genetics.utah.edu/content/labs/
Other Virtual Lab:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
Pedigree definition
Pedigree: a family history that shows how a trait is inherited over several generations
Pedigrees are usually used when parents want to know if they are carriers of a particular disorder
Making a Pedigree
Female
Male
Married Couple
Siblings
Filled in symbols indicate individual is affected with a disorder
Example of a Pedigree
You
Parents
Aunts, UnclesAunts, Uncles
GrandparentsGrandparents
BrotherDo any disorders run in this family??
Interpreting a Pedigree What can you tell from a pedigree?
Whether a family has an autosomal or sex-linked disease or disorder Autosomal disorder: appears in both
sexes equally Sex-linked disorder: allele is located only
on the X or Y chromosome. Most sex-linked genes are on the X chromosome and are recessive
So who would have an X-linked disorder more often, boys or girls?
Whether a disorder is dominant or recessive
Is this disorder 1) autosomal or sex linked, 2) dominant or recessive?
You
Parents
Aunts, UnclesAunts, Uncles
GrandparentsGrandparents
Brother
Sex Linked! (in this case allele is recessive and located on the X chromosome)
Is this disorder 1) autosomal or sex linked, 2) dominant or recessive?
You
Parents
Aunts, UnclesAunts, Uncles
GrandparentsGrandparents
Brother
Autosomal dominant!
Is this disorder 1) autosomal or sex linked, 2) dominant or recessive?
You
Parents
Aunts, UnclesAunts, Uncles
GrandparentsGrandparents
Brother
Autosomal recessive!
Common Genetic Disorders
Color blindness Sickle cell anemia Cystic Fibrosis Hemophilia Huntington’s Disease
For more info, go to: http://www.ncbi.nlm.nih.gov/pubmedhealth/
Color Blindness
Deficiency to percieve colors
Problem with color-sensing pigments in certain nerve cells of the eye
About 1 in 10 men have some form of color blindness.
Sex-linked disorder
Sickle Cell Anemia Disorder where
abnormal hemoglobin (a protein inside red blood cells) is produced and warps red blood cells
Sickle cells deliver less oxygen to body’s tissues and can get stuck in small blood vessels
Recessive trait, tends to be seen in people of African or Mediterranean descent
Cystic Fibrosis Recessive, autosomal disease Life threatening, causes thick mucus
to build up in various areas of the body (lungs, digestive tract, etc).
Tends to run in Caucasians, of Northern/Central European descent
(1 in 29 Americans carry the allele) Average life span in US for people with CF is 37, death usually caused by lung complications
Hemophilia Bleeding disorder, where it takes a
long time for blood to clot (body lacks proteins involved in clotting)
Sex-linked (carried on the Xchromosome)
Treatmentinvolves injection with missing clotting protein