Lesson 2

• PRIMARY MITOCHONDRIAL MYOPATHY


  Mitochondrial disorder caused by defects in the DNA found in mitochondria, with strictly maternal inheritance passed to the child
• Chimera


  An organism or tissue that contains at least two different sets of DNA, most often originating from the fusion of different zygotes. When an embryo dies, the surviving fetus will absorb some cells of deceased twin, resulting in the surviving fetus having two sets of DNA.
• Genomic imprinting


  The process by which only one copy of a gene in an individual (either from their mother or their father) is expressed, while the other copy is suppressed.
• Angelman syndrome


  • Short and broad skull
  • Large tongue
  • Small head
  • Wide mouth
  • Widely spaced teeth
  • Large lower jaw
• Mosaicism


  When a person has two or more genetically different sets of cells in his or her body. If those abnormal cells begin to outnumber the normal cells, it can lead to disease that can be traced from the cellular level to affected tissue, like skin, the brain, or other organs.
• Sex-influenced traits


  Traits that are differently expressed in two sexes due to the influence of sex hormones, making the expression of traits more dominant in males than in females.
• 1. Linked Inheritance in Fragile X Syndrome

  • Unaffected father
  • Carrier mother
  • Unaffected son
  • Unaffected daughter
  • Carrier or affected daughter
  • Affected son
• Sex-limited traits


  • Traits that are expressed in only one sex but not in other sex due to the activation of sex hormones.
• Sex-linked Inheritance


  • Genes for some traits are found on the sex chromosomes (X or Y), most of which are recessive and the normal gene is dominant.
• Heterozygous Females (XXᶜ)


  Carriers who do not show the trait but carry a gene for the trait.
• Homozygous Females (XᶜXᶜ)


  Have the trait.
• Males with the gene (XᶜY)


  Have the trait as they do not have another X to counterbalance the affected gene.
• Gene linkage


  Genes found on the same chromosome that are close together and tend to be inherited together, while genes on a chromosome that are farther away have a higher chance of separating during recombination.
• Epistasis


  When an allele of one gene hides or masks the visible expression or phenotype of one gene, which is entirely different from dominant and recessive genes.
• Polygenic traits


  Traits influenced by two or more genes.
• Epistasis


  When an allele of one gene hides or masks the visible expression or phenotype of one gene
• Epistasis Example


  Labrador Retrievers
• Labrador Retrievers


  • Their coat color is controlled by two sets of allele
  • E- determines whether the fur will have dark pigment
  • B- determines how dark the pigment will be
• Labrador Retrievers


  • BBEE, BBEe and BbEe for Black retrievers
  • bbEE and bbEe for brown retrievers
  • BBee, Bbee, or bbee for golden retrievers
• Polygenic traits


  • It is influenced by two or more genes
  • It require more than one gene (allele) to determine trait
• Multiple alleles


  This involves more than just the two typical alleles that code for a certain characteristic
• Alleles of Multiple Alleles

  • C
  • cᶜʰ
  • cʰ
  • c
• Genotype of Multiple Alleles

  • CC
  • cᶜʰcᶜʰ
  • cc
• Phenotype of Multiple Alleles

  • WILD TYPE: Brown fur
  • CHINCHILLA: Black-tipped white fur
  • HIMALAYAN: White fur with black paws, nose, ears, tail
  • ALBINO: White fur
• Blood type displays both codominance and complete dominance


  • Red Blood cells can either have a carbohydrate on their surface or not
  • The presence of a carbohydrate (I) is dominant to the absence of a carbohydrate (i)
  • There are two types of carbohydrates that may exist on the surface of RBCs called A (IA) and B (IB)
  • Cell surface carbs A and B are codominant, which means they could also show up at the same time on an RBC
• Codominance in blood types


  • A person with the IA allele will have A carbohydrates
  • A person with the IB allele will have B carbohydrates
  • A person with both A and B alleles will have both A and B carbohydrates
  • A person with the recessive i allele will have no carbohydrates
• Codominance


  • Having both alleles expressed equally in the phenotype of the organism
  • Both traits are dominant
• Codominance Examples


  • Roan cow
• Incomplete Dominance Examples

  • Chestnut brown horse
  • White horse
  • Palomino horse
• Incomplete Dominance


  • One allele is not completely dominant over the other allele
  • Results in an offspring of intermediate phenotype
• Incomplete Codominance Example

  •Probability of pink flowers if red flowers are bred with white flowers?

  
• Incomplete Codominance

  •Probability of pink flowers if pink flowers are bred with red flowers