Topic 12 pt 2: Pedigree Analysis

Question 1

Characteristics of an autosomal dominant trait

Answer 1

• both sexes in equal frequency
• both sexes transmit to offspring
• does not skip generations
• affected offspring must have affected parent

Question 2

Answers to four questions for autosomal dominant trait

Answer 2

1. Yes (dominant)
2. No (autosomal)
3. Yes (autosomal)
4. Dominant

Question 3

Examples of autosomal dominant traits

Answer 3

Dwarfism, huntington’s disease

Question 4

Describe Huntington’s disease

Answer 4

• late age of onset
• neurodegeneration
• genetic testing available
• often affected individuals have already conceived
• earlier and earlier disease onset in later generations

Question 5

Characteristics of X-linked recessive trait

Answer 5

• more males than females affected
• affected sons are born to unaffected mothers
• half a carrier mother’s sons are affected
• never passed from father to son
• all daughters of affected fathers are carriers

Question 6

Answers to questions for X-linked recessive traits

Answer 6

1. Sort of
2. Yes more males (X linked)
3. No
4. Yes (recessive)

Question 7

Example of X-linked recessive trait

Answer 7

Hemophilia (inability to clot blood)

Question 8

Characteristics of X-linked dominant traits

Answer 8

• males and females affected, usually females>males
• does not skip generations
• affected sons must have affected mother
• affected fathers pass trait to all daughters
• affected mothers pass trait to half their sons and half daughters (het)

Question 9

Answers to questions for X-linked dominant trait

Answer 9

1. Yes (dominant)
2. Not really
3. No (could be sex linked)
4. No (dominant)

Question 10

Examples of X-linked dominant traits

Answer 10

Hypophosphatemia
- impaired phosphate transport
- impaired absorption of Ca and P by intestines
- rickets

Question 11

Characteristics of Y-linked traits

Answer 11

• only males affected
• passed from father to all sons
• does not skip generations

Question 12

Mitochondrial and chloroplast traits and disorders are inherited always from..

Answer 12

The female or mother
Organelles and cytoplasm have their own DNA and are inherited maternally

Question 13

Main function of the mitochondria

Answer 13

Oxidative phosphorylation (ATP)

Question 14

Genetic material of mitochondria is called…
How many bp in mitochondrial DNA? genes?

Answer 14

mtDNA
17,000 bp, few genes

Question 15

How many genes function for ox phos in mtDNA

Answer 15

13

Question 16

Homoplastic vs heteroplastic

Answer 16

Homoplastic = all mitochondria or chloroplasts have the same genotype in a single cell
Heteroplastic = mix of genotypes

Question 17

Why does expression of mitochondrial genetic disorder vary in individuals

Answer 17

Multiple mitochondria in every cell
Homoplastic = no disease or severe disease
Heteroplastic = highly variable disease expression

Question 18

Characteristics of mitochondrial inheritance

Answer 18

• effects males and females
• affected females pass on trait to most offspring (males and females)
• never passed by affected males to offspring
• variable expression of disorder

Question 19

Examples of mitochondrial traits

Answer 19

• Myoclonic epilepsy and ragged-red fiber
• Leber hereditary optic neuropathy