mendelian inheritance

Question 1

what is the p arm on a chromosome

Answer 1

petite arm

Question 2

what is the q arm on a chromosome

Answer 2

long arm

Question 3

mendelian inheritance

Answer 3

states individuals possess two alleles and a parent passes only one allele to his/her offspring. Mendel’s Law of Independent Assortment states the inheritance of one pair of factors ( genes ) is independent of the inheritance of the other pair.
focuses on single gene disorders

Question 4

disease associated mutations

Answer 4

alter protein function

difference between functional and non-functional is what causes the disease

Question 5

sickle cell disease

Answer 5

• Abnormal Hb gene - single base change
• Sickle cell disorders are inherited. The screening process for SCD also identifies carriers of some haemoglobin variants.
• Leads to:
  ○ Pain; cold, dehydration, infection; jaundice, stroke, leg ulcers, eyes, kidneys; anaesthetic issues
• African, Mediterranean, middle-East, Indian - provides immunity to malaria
  
  • sickle cell disorders cause red blood cells to become sickle-shaped, and that this can cause pain, tissue damage, infection and even death. The sickle blood cells block the blood vessels.
    Early treatment by 2 months of age can improve the health of babies with SCD and prevent deaths.

Question 6

carriers

Answer 6

carry the gene for the functional protein and the non-functional protein

Question 7

affected

Answer 7

carry two genes for the non-functional protein

Question 8

cystic fibrosis

Answer 8

• Caused by a single gene
• > 3000 mutations
• One is particularly common: NW to SE gradient across europe, 1/25 in UK carrier, 1/2500 affected
• build up of thick sticky mucus in the lungs and digestive system
• autosomal recessive

Question 9

achondroplasia

Answer 9

short limbed dwarfism (proximal limb shortening)

• Dominant inheritance - having the abnormal protein causes disease (non-functional or missing protein or protein hat has gain of function)
• Each child has a 50% chance of inheriting the mutation
• No skipped generations
• Chance doesn’t change with each pregnancy
• Equally transmitted by men and women
• Male to male transmission - not X linked

Question 10

if neither the mum or the dad have achondroplasia, what is the chance of the child being born with the condition

Answer 10

There is a very low chance of this child being born with achondroplasia as neither the mum or the dad have it
(however not truly 0 as dominant disorders can be a result or a random genetic mutation - neither of the parents have the condition but the child is born with it)

Question 11

huntington’s disease

Answer 11

• Autosomal dominant
  
  • Neuro-degenerative, late onset (middle age years are typical), if they have reached 60y/o or above and have shown no features they are unlikely to develop it
    If one parent has the condition, the risk to the child is 1/2

Question 12

Duchenne muscular dystrophy

Answer 12

• X linked
  
  • Fatal in early adult life
    Carrier testing, prenatal diagnosis, pre-implantation diagnosis

Question 13

x linked inheritance

Answer 13

• Only males affected characteristically
  
  • Can skip generations
  • Unaffected women and affected men can transmit the condition
    No male to male transmission i.e. a man with an X linked condition cannot pass the condition to his son