Principles Of Genetic inheritance

Question 1

Homologous Chromosomes Characteristics

Answer 1

• pair of chromosomes
• 2 copies of each gene
• • 2 order of the 4 loci being identical

Question 2

Metacentric, Submetacentric, acrometric

Answer 2

Metacentric= equal length of short arm p and long arm q

Submetacentric= shorter on arm p than q

acrometric= small , short long arm q and stalk/satelitte in short arm p

Question 3

Chromosomal Nomenclature

Answer 3

arm(p or q)> region(1 or 2) > band (1-4) > subband (1-5)

Question 4

Mitosis in Stem Cells

Answer 4

two cells

• one daughter cell
• one stem cell

Question 5

Ways of Genetic Diversity for Meiosis

Answer 5

1) homologous recombination
2) random segregation
3) De novo mutations

Question 6

Meiosis rounds of what?

Answer 6

• one round of DNA replication

- two rounds of nuclear divisions

Question 7

Types of Translocation

Answer 7

Translocation

• NON-HOMOLOGOUS chromosomes exchange genetic material
  a) Reciprocal- an exchange of material between nonhomologous chromosomes
• **b) Robertsonian - one long arm of two acrocentric chromosome com bine, short arm lost

Question 8

Types of Trisomy

Answer 8

Trisomy 21- Down Syndrome

• most common
• can also occur through translocation (46XX 14:21) or mosaic

Trisomy 13- Patau Syndrome

• severe developmental abnormalities
• death within 1 week

Trisomy 18- Edwards Syndrome

• abnormal development
• death within 1 year

Question 9

Genomic Imprinting

Answer 9

where ONE of the alleles is transcriptionally inactive

Question 10

Prader-Willi and Angelman Syndrome

Answer 10

PW

• mom is imprinted (PW is inactive and AS is active)
• dad has deletion of PW and AS genes in chromosome 15
• SON : short and small , obese, intellectual disability

Angelman

• dad is imprinted ( PW is active and AS is inactive)
• mom has deletion of PW and AS genes in chromosome 15
• DAUGHTER: ataxic gait, seizure, intellectual disability

Question 11

Uniparental Disomy

Answer 11

GENOMIC IMPRINTING and NON DISJUNCTION
- both chomosoms inherited from same parent
that is imprinted=> no gene product

Question 12

Effects of Consanguinity

Answer 12

• more likely to produce offspring affected by autosomal recessive disorders
• mortality rates up to 9% higher than general population
• Each person carries 1-5 recessive mutations lethal to offspring if matched with another copy of mutation (homozygosity)

Question 13

Mitochondrial DNA (mtDNA)

Answer 13

• contains NO introns
• only through maternal line
• transcription done in mitochondria, NOT nucleus
• mutation rate 10x higher than DNA
  
  • bc lack of DNA repair mechanism
  • more free radicals formed in OxPhos

Question 14

Mitochondrial Disorders (2)

Answer 14

1) Leber’s hereditary optic neuropathy (LHON)
- degeneration of retinal ganglion cells
- loss of central vision

2) Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode (MELAS)
- affect brain, muscle, CNS
- stroke and dementia
- lactic acidosis

Question 15

Multifactorial Inheritance

• factors
• patterns

Answer 15

Factors: polygenetics and environmental factors

Patterns:

• recurrence risk higher is disease from least commonly affected sex
• recurrence risk higher when more than 1 family member is affected
• if expression more severe in proband, recurrence risk is higher