Genetics Week 13 Flashcards
What is translocation
- It is the interchange of genetic material between non homologous chromosomes
Name the 2 types of Translocation
- Reciprocal Translation
-Robertsonian Translocation
What does Reciprocal Translocation involve
-Involve breaks in two different chromosomes with mutual exchange of material.
Resulting in derivative chromosomes.
When does Robertsonian Translocation occur
- They occur when the short arms of 2 acrotentric chromosomes(13,1415,21+22) are lost and the long arm fuses at the centromere to form a single chromosome
Explain the what happens to the carriers + offspring of Reciprocal Translocation
Carriers:
-Usually have a normal phenotype as the genetic material is balanced.
-Offspring may inherit duplications or deletions, leading to partial trisomies or monosomies with abnormal phenotypes.
Explain what happens to the carriers and offspring with Robertsonian Translocation
Carriers:
-Have 45 chromosomes but are phenotypically normal.
-Offspring may inherit unbalanced chromosomes, leading to monosomies or trisomies of the long arms.
Why do deletions occur
They occur due to a chromosome break, leading to the loss of genetic material
Name the 2 types of deletions
- Terminal deletions
-Interstitial deletions
What is terminal deletions
-The loss of the chromsomes tip following a single breake
What is interstitial deletions
- Loss of material between two breaks
How are zygotes formed with deletions
A gamete with a deletion usually combines with a normal gamete, forming a zygote with one normal chromosome and one with a deletion.
Give an example of a Deletion syndrome
Cri-du-chat syndrome
What is Cri-du-chat syndrome
- Deletion of the distal short arm of chromosome 5 (46,XY,del(5p)).
What are characteristics of Cri-du-chat syndrome
-“cat-like” cry in infants.
-Intellectual disability
When does UniParental Disomy occur(UPD)
Uniparental disomy (UPD) occurs when both copies of a chromosome come from one parent, and none are contributed by the other parent.
