Human pathologies collo 2

Question 1

The most common form of polyploidy in human is?

Answer 1

Triploidy (3n), caused by the fertilization of an egg by two sperm (dispermy).

Meiotic failure - a diploid sperm or egg cell is produced, can also produce a triploid zygote.

Question 2

The most common cause of aneuploidy (2n +1/-1) is?

Answer 2

Nondisjunction, the failure of chromosomes to disjoin

normally during meiosis.

Question 3

Somatic mosaicism - refers to the?

Answer 3

Occurrence of two genetically distinct populations of cells within an individual, derived from a postzygotic mutation

Question 4

Germ line mosaicism refers to?

Answer 4

The presence of genetically distinct groups of cells within germ line tissues.

Question 5

What is tumorigenesis - genomic instability?

Answer 5

Tumour cells typically are characterized by widespread
alteration in DNA, chromosome breaks, and aneuploidy.
This condition is termed genomic instability.

Question 6

Human pathology and nucleotide excision repair?

Answer 6

For example Xeroderma pigmentosum, symptoms like skin photosensitivity, pigmentary lesions etc.

Question 7

Human pathology involving Homologous recombination repair (HR) and Non-homologous end joining (NHEJ)?

Answer 7

Defective repair of DSBs can result in chromosomal
instability, which is characterized by rearrangements and loss of chromosomes.

A number of human syndromes, are associated with defects in DSB repair (e.g. hereditary breast/ovarian cancer).

Question 8

Ion channel defect and human pathology?

Answer 8

Cystic fibrosis.
Caused by allelic variants in a CFTR gene - encodes
cyclic AMP regulated chloride ion channels transmembrane protein in epithelial cell membranes.

Abnormally viscous secretions in the airways of the lungs and in the ducts of the pancreas in individuals with CF cause obstructions that lead to inflammation, tissue damage and destruction of both organ systems.

Question 9

Receptor mediated endocytosis and human pathology? (low-density lipoprotein)

Answer 9

Familial hypercholesterolemia.

Patients with this disease have very high levels of serum cholesterol and suffer heart attacks early in life.

Caused by allelic variant in LDLR gene.

Question 10

GPCRs and human pathology?

Answer 10

Cholera - an infectious disease that causes acute diarrhea, with dehydration and even death if untreated.

Cholera toxin modifies G protein alpha subunit and inhibits GTPase activity;

As the result, the effector molecule adenylyl cyclease
remains inactive, the secondary messenger is not generated!

Question 11

Receptor tyrosine kinase and human pathology?

Answer 11

Achondroplasia - form of short-limbed dwarfism.

Allelic variant Gly380Arg (98%), in the transmembrane
domain of fibroblast growth factor receptor 3 (FGFR3);

Question 12

Ligand-gated ion channels and human pathology?

Answer 12

Congenital myasthenic syndrome:

Early-onset progressive muscle weakness;

Allelic variants of CHRNA1 gene, coding for nicotinic
acetylcholine receptor (AChR);

The disorder results from kinetic abnormalities of the
acetylcholine receptor (AChR) channel, specifically from abnormally brief opening and activity of the channel, with a failure to reach the threshold for depolarization.

Question 13

Intracellular receptors and human pathology?

Answer 13

Androgen insensitivity syndrome.

Disorder affects males, they have female external genitalia, female breast development, blind vagina, absent uterus and abdominal or inguinal testes, despite a normal male 46,XY karyotype.

Allelic variants in AR gene encoding for androgen receptor.