Mendel in Molecular Terms

Question 1

Types of DNA mutation

Question 2

Synonymous versus non-synonymous genetic changes and effect on genetic translation codes
also explain what a nonsense mutation is

Answer 2

1.Silent or synonymous mutations (no change in AAs)
UUU UGC —> UUC UGU
= Phe Cys —> Phe cys

2. Misssense or non-synonymous mutations
   UUU UGC —> CUU CGU
   Phe Cys —> Leu Arg (changes in AAs)
3. Nonsense mutation —> introduction of a stop codon
   UGU —> UGA
   Cys —> Stop

Question 3

INDELS

Answer 3

Insertion or deletion

Question 4

Nonsense

Answer 4

stop condon being mutated on

Question 5

Missense

Answer 5

a nonsynonymous single base substitution

Question 6

Silent

Answer 6

a synonymous single base substitution

Question 7

Frame shift

Answer 7

from insertion or deletion = new fx or loss Fx of resulting protein ( changing the triplets read as codons)

Question 8

Splice site genetic mutation

Answer 8

• mutation Ltx at splice control sequences = altering RNA splicing pattern
  = resulting —> RNA length and structure change = cascades to protein length and structure change.

Question 9

Splice site genetic mutation can result in?

Answer 9

a frame shift mutation.

Question 10

example myotonic or fainting goats

Answer 10

Case study 1 - myotonic or fainting goats
Goat muscle chloride
Alanine to proline
Non synonymous or missense mutation
Results in diminished chloride conductance in myotonic (inability to relax muscle) muscle and delays relaxation muscle

Question 11

Hereditary goitre in Afrikander cattle

Answer 11

Case study 2 - Hereditary goitre in Afrikander cattle
abnormal thyroglobulin (Tg) the precursor of thyroid hormone
A stop codon Goitre (TGA - stop) replaces a Arginine CGA.
Thus nonsense/nonsynonymous mutation
Results mRNA full length but protein shorter than normal
Autosomal recessive disorder
Homozygotes have a smaller and non-functional Tg protein

Question 12

Case study 3 - Dwarfism in Flackvieh cattle

Answer 12

a example of deletion = results in early termination of translation = truncated protein = protein abnormal fx
Clinical presentation = phenotypic manifestation of dwarfism, crooked back, muzzle structural abnormal and brachygnathia inferior

Question 13

Case study 4 - muscular Dystrophy in Golden Retrievers

Answer 13

Clinical presentation = difficulty swallowing, poor body condition, protruding tongue, stertorous breathing, exercise intolerance and generalised muscle atrophy
X linked myopathy
Dystrophin not in skeletal muscle
Progression = muscle necrosis —> fibrosis and joint contracture @ 6m. —> Death via cardiac or respiratory failure
Eg of splice site mutation in intron = complete deletion of exon on the mRNA —> a subsequent frameshift in protein.

Question 14

Locations where mutations can occur an their effects on proteins

Answer 14

somatic and germ-line mutations

Question 15

Somatic mutations

Answer 15

occur in non-reproductive cells
Creates a cline of mutant cells ( if this occurs in the embryo it becomes more widespread
Many have no phenotypic effect

Question 16

Germ-line mutations

Answer 16

occurs in gametes therefore may be passed on to next generation
Therefore offspring will all carry the genetic mutation

Question 17

Question 18