Genetics basis of disease

Question 1

Describe how proteins are generated from DNA encoded within genes including a description of transcription and translation and introns and splice variants

Answer 1

Proteins are generated from the DNA via transcription and translation.Transcription is the process that copies the DNA strand into RNA and leaves the nucleus. Translation is the process in which ribosomes in cytoplasm synthesis proteins.They do this by translating the sequence of mRNA molecule to a sequence of amino acid .
Intron are the non-coding region for protein in DNA and they are removed by the splicesome.

Question 2

Define different types of DNA mutation and explain how these impact on protein function

Answer 2

Translation-replacing a purine with a purine or a pyrimidine with a pyrimidine
Tranversion-replacing a pyrimdine with a purine and a purine with pyrimdine.
Deletion-deleting on or two proteins
Insertion -inserting one or two protiens.

Question 3

Define different types of DNA mutation and explain how these impact on protein function

Answer 3

Translation-replacing a purine with a purine or a pyrimidine with a pyrimidine
Tranversion-replacing a pyrimdine with a purine and a purine with pyrimdine.
Deletion-deleting on or two proteins
Insertion -inserting one or two proteins.

Question 4

Explain is meant by recessive and dominate inheritance

Answer 4

Recessive-you need both parent to give you the gene for it to be expressed.This gene is masked by the dominant gene.
Dominant inheritance-you just need one of the genes for it to be expressed.

Question 5

Provide examples and an explanation of what is meant by sex-linked and autosomally-inherited disease

Answer 5

Sex linked- A genetic disorder caused by or linked to gene(s) located in the sex chromosome.
Examples include:Duchenne and Becker muscular dystrophy

Autosomal inherited-a genetic disorder that is not related to the sex chromosomes.
Examples autosomal recessive :cystic fibrosis,sickle anaemia

Question 6

Describe, with examples, some of the different chromosomal aberrations that lead to disease

Answer 6

1) Mosaiscism
2) Translocation
3) Isochromosomes
4) Ring Chromosomes
5) CNV(copy number variation)
6) Deletions
7) Inversions

Question 7

Describe, with reference to the underlying genetic defects, the pathophysiology of Huntington’s disease

Answer 7

It is an inherited

dominant autosomal disease . It is caused by the increase of repeats(above 40) of the C-A-G in the HD gene.

Question 8

Describe, with reference to the underlying genetic defect, the pathophysiology of cystic fibrosis

Answer 8

Mutations in the CFTR gene cause the CFTR protein to malfunction or not be made at all, leading to a buildup of thick mucus, which in turn leads to persistent lung infections, destruction of the pancreas, and complications in other organs. Cystic fibrosis is an example of a recessive disease.