are these MCQ'S right? - (Jun/15/2007 )

Hi there,

had an exam yesterday and just wanna make sure i got a few MCQ'S right-the ones i chose are in bold..i write these up cos these are the ones i was unsure about

1) Oct4 is a transcription factor required for stem cell maintenance. the cells/tissues in which you would expect Oct4 to be expressed are:-

zygote, morula, inner cell mass, ES cells
zygote, morula, inner cell mass, neurons
inner cell mass, morula, ES cells, neural stem cells
zygote, morula, inner cell mass, trophoblast

2) which of these statements about tumour supprssor genes (TSGs) is UNTRUE

the retinoblastoma and P53 genes are examples of TSGs
mutation or loss of a TSG invariably causes cancer
mutation or loss of a TSG is usually genetically recessive
they code for proteins which regulate normal growth or cell cycle progression

3) A yeast 2-hybrid assay wld be used to identify:-

a reporter gene
the protein that binds to a known regulatory sequence
the binding partner for a transcription factor
a consensus sequence in a promoter

4)which of the following statements is INCORRECT

3 classes of RNA polymerase molecules are found in eukaryotic cells
changes in gene expression in prokayotes generally are in response to environmental factors
transcriptionally active DNA is relatively resistant to nuclease digestion in eukaryotes
in prokaryotes the default state is usually for genes to be expressed unless regulatory proteins bind to the DNA and prevent transcription

5) enhancer sequences:=

control tbe binding of the small ribosomal subuni to the 5' end of a mRNA molecule
contain a TATA box
are found only in the genomes of prokayotes
may be upstream or downstream of the transcription start site

6) mitochondrial precursor proteins contain:-

an N-terminal SKL sequence
a C-terminal motif
an N-terminal amphipathic alpha-helix
mannose 6-phosphate residues

cheers,
biology_06er

6. mitochondrial precursor protiens have a N terminal sequence with the alpha helix.

5. may be upstream or downstream of the transcription start site

check the others in some textbook.