Genetics

Question 1

Start codon

Answer 1

ATG

Methionine

Question 2

Stop codon

Answer 2

TAA
TAG
TGA

Question 3

TAA

Answer 3

Stop codon

Question 4

TAG

Answer 4

Stop codon

Question 5

TGA

Answer 5

Stop codon

Question 6

ATG

Answer 6

Methionine

Question 7

Hypoxia-induced factor

Answer 7

Transcription factor
Dimer
High O2 = unstable alpha subunit, degraded to proteasome
Low O2 = stable alpha subunit, active dimer, enters nucleus - recognises promotors (consensus sequences) of proteins which can survive in low oxygen levels

Question 8

Steroid hormones - nuclear receptors

Answer 8

Act via nuclear receptors
Nuclear receptor, no hormone bound = inactive
Steroid binds to nuclear receptor = activate nuclear receptor (dimerise)

Active nuclear receptor/hormone (transcription factor) enters nucleus
Binds to response elements to regulate the transcription of other genes

Question 9

Rubinstein-Tayra Syndrome

Answer 9

Disease due to a malfunctioning transcription factor - CRE

CRE-binding protein (CRE-BP) is phosphorylated - binds to a wide-spread response element called CRE
CRE found in many activity-depenendent genes (100s f genes)

CRE = cAMP-response element
Stimulate adenylate cyclase, increase cAMP, increase PKA
PKA phosphorylates CRE and activates

cAMP = allosteric modulator - a substance which indirectly modulates the activity of a primary ligand (modulates PKA, which P CRE to activate)

Question 10

Fibronectin

Answer 10

Splice variants

Fibroblasts - longer, attached to extracellular matrix
Hepatocytes - secreted into blood stream, involved in coagulation

Question 11

Spinal muscle atrophy

Answer 11

2 genes encode SMN genes

SMN2 gene has a silent mutation in exon - most SMN2 produced mRNA is spliced incorrectly + degraded

If there is an inactivating mutation in SMN1, only SMN2 can supply the SMN protein, but in low quantities
Enough SMN protein for embryonic life
Post-natal life leads to early pathology + mortality <10y/o