Pre-Exam Stuff

Question 1

Name the example of incomplete dominance mentioned in the lecture, and name the receptor affected by the mutation

Answer 1

Familial hypercholesterolaemia (LDL receptor)

Question 2

Define maternal imprinting

Answer 2

The maternal allele is imprinted and silenced, the paternal allele is preferentially expressed in the embryo

Question 3

Describe the impact of maternal imprinting for the Igf2 gene

Answer 3

(In mice which are heterozygous for the Igf2 mutation) if the mutant allele is inherited from the mother, the normal paternal allele is preferentially expressed and the phenotype is normal.
If the mutant allele is inherited from the father, the mutant allele is expressed -> dwarf phenotype

Question 4

Name two human syndromes due to genomic imprinting (and which is maternal/paternal)

Answer 4

Prader-Willi syndrome (deletion of paternal origin)
Angelman syndrome (deletion of maternal origin)

Question 5

How does the SRY gene confer “maleness”?

Answer 5

SRY is a Transcription Factor, thought to regulate the genes necessary for testis formation

Question 6

Why is there such phenotypic variability between members of a family affected by mitochondrial DNA mutations?

Answer 6

Maternal inheritance (mothers pass them on to ALL children, fathers pass them on to NONE)

Question 7

What two main types of genes are found in mitochondrial DNA?

Answer 7

Components required for translation, and proteins involved in oxidative phosphorylation

Question 8

Where are embryonic stem cells taken from?

Answer 8

Epiblast (part of inner cell mass) of pre-implantation blastocyst

Question 9

Why are embryonic stem cells considered pluripotent, but not totipotent?

Answer 9

They can give rise to all somatic and germ cells, with the exception of some Extraembryonic Membranes