Human Genetics

Question 1

Karyotype

Answer 1

• a preparation of an individual’s metaphase chromosomes
• used to show chromosome morphology
• can tell us about the size, staining patterns and centromere position
• can show structural abnormality or changes in chromosome number

Question 2

Pedigree Analysis

Answer 2

• study of phenotypic records of a family over several generations
• look for expression of trait.
• can be used to determine whether a trait is dominant or recessive
• by examining a pedigree analysis, one can determine whether a mutated gene is dominant or recessive

Question 3

Mode of inheritance

Answer 3

• the mechanism by which the trait(s) is/are inherited
• most human genes are inherited in a Mendelian manner
• usually unaware of a problem unless a mutation is present in the population which causes an abnormal or different phenotype.

Question 4

Autosomal Dominant

Answer 4

• condition is passed from one generation to the next as evidenced by a pedigree analysis
• most mating will be in the form of heterozygote to homozygote
• Mm x mm
• 50% chance o receiving / being affected by the gene.
• both male and female are affected and can pass it with equal probability.

Question 5

Autosomal Recessive

Answer 5

• will only manifest itself when it is in its homozygous state.
• affected individuals have normal parents, both which are heterozygous (and don’t know they are carriers of the mutation)
• trait skips a generation
  the disorder often appears to be unique or sporadic w/out any known family history.
• Nn x Nn
• 25% affected (nn)
  -50% non-affected heterozyotes carriers (Nn)
• 25% normal

Question 6

Examples of Autosomal Dominant Diseases

Answer 6

• Absence of fingerprints
• Achondroplasis
• Cleft Chin
• Polydactyl
• Woolly hair
  Osteogenesis imperfecta (brittle bone disease)

Question 7

Examples of Autosomal Recessive Disease

Answer 7

• Tay Sach disease
• Cystic Fibrosis
• Sickle Cell Anem

Question 8

Chromosomal Structure Mutations

Answer 8

• Mutations that affect the chromosomes

Question 9

Deletions

Answer 9

• Removal of genetic information
• Could be deleterious to organism
  
  • or not if the genetic info is not needed for survival
• (can identify under microscope)

Question 10

Duplication

Answer 10

• Addition of genetic information
• creates an imbalance of genetic information
• it may be tandem )adjacent) or reverse
• (can identify under microscope)

Question 11

Inversion

Answer 11

• Occurs by a breakage in the chromosome and the rotation of the fragments 180 degress before they rejoin
• amount of genetic info is the same, but the order is different
  (cannot identify under microscope)

Question 12

Inversion [continued]

2 types of Inversion

Answer 12

1. ) Paracentic-Inversion
   - occurs outside of the centromere
   - does not involve the centromere
2. ) Pericentric-Inversion
   - involves or spans the centromere

Question 13

Translocation

Answer 13

• occurs when 2 nonhomologous chromosomes mutate by exchanging parts
• type of mutation may drastically alter the size of a chromosome as well as the position of the centromere

Question 14

Changes in Chromosomal Number

Answer 14

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Question 15

Nondisjunction

Answer 15

Failure of chromosomes or chromatids to seperate during meiosis