Human Heredity • Humans have 46 chromosomes – 22 pairs of Autosomes (body cells) – 1 pair of Sex chromosomes (XX or XY) • Chromosomes can be cut up and arranged in a Karyotype. – Females are XX – Males are XY • There is a 50% chance of having a boy or 50% chance of having a girl. • Humans with more or less than 46 chromosomes tend to have serious disorders. – Called chromosomal disorders
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Human Heredity Humans have 46 chromosomes –22 pairs of Autosomes (body cells) –1 pair of Sex chromosomes (XX or XY) Chromosomes can be cut up and arranged.
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Human Heredity
• Humans have 46 chromosomes– 22 pairs of Autosomes
(body cells)– 1 pair of Sex chromosomes
(XX or XY)• Chromosomes can be cut up
and arranged in a Karyotype.– Females are XX– Males are XY
• There is a 50% chance of having a boy or 50% chance of having a girl.
• Humans with more or less than 46 chromosomes tend to have serious disorders.– Called chromosomal disorders
What is a Karyotype?
• A cell is photographed in mitosis when chromosomes are fully condensed and easier to see.
• They are cut from photographs and arranged into pairs.
• This is called a karyotype.
Chromosomal Disorders• Due to a failure in
meiosis, homologous chromosomes will fail to separate properly.
• Called Nondisjunction.
• Therefore, abnormal (+ or -) numbers of chromosomes will end up in the gametes.
• Recessive Disorders: Sex-linked– Colorblindness – the disability to perceive colors in the
cones of the eyes. red/green (1:10 males) & (1:100 females)
– Hemophilia – blood fails to clot after injury (1:10000 males)• Hemophilia figured prominently in the history of European royalty in the 19th
and 20th centuries. Queen Victoria, through two of her five daughters passed the mutation to various royal houses across the continent, including the royal families of Spain, Germany and Russia. Victoria's son Leopold suffered from the disease. For this reason, hemophilia was once popularly called "the royal disease".
– Duchenne Muscular Dystrophy –weakening and loss of skeletal tissue (1:3500 boys)
Duchenne Muscular DystrophyMuscles are made up of bundles of fibers (cells). A group of interdependent proteins along the membrane surrounding each fiber helps to keep muscle cells working properly. When one of these proteins, dystrophin, is absent, the result is Duchenne muscular dystrophy; poor or inadequate dystrophin results in Becker muscular dystrophy.
Diseases/Disorders you should know!
• Dominant Disorders: Autosomal– Achondroplasia – A genetic form of Dwarfism (1:30000) – Huntington’s Disease –A wasting away of brain tissue,
causes uncontrolled movements, emotional disturbances and mental deterioration. Is fatal (8:100000)
• Huge problem in passing to children without even knowing! Tested for often.
• CoDominant Disorders: Autosomal– Sickle Cell Anemia – Misshapen red blood cells due to a
mutation in hemoglobin, the protein that carries oxygen in the blood. Causes pain and damage to tissues (72,000 US, 1:500 African-American births, 1:1200 Hispanic births)