The Nucleus

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how many different proteins make up the nuclear pore complex?
30 different proteins
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how many total proteins make up each nuclear pore complex?
500 - 1000
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what is the name of the proteins within nuclear pore complex?
Nucleoprorins
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roughly how many nuclear pore complex's are in a mammalian cell?
3000 - 20,000
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what size does a molecule need to be to freely diffuse across the NPC?
< 5000Da
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How would a molecule less than 60KDa travel across the NPC
diffuse slowly
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what size would a molecule be if it required a specialised mechanism to travel across NPC
>60KDa OR 60,000Da
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What is the name of the signal sequence for a protein destined to pass the NPC
Nuclear localisation Signal
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where is the nuclear localisation signal located on the protein sequence
anywhere
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what is the NLS recognised by?
Nuclear import/export receptors (Importins)
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What do nuclear import receptors bind to?
FG Repeats on nucleoporins
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what amino acids do FG repeats have heavily?
phenylalanine(F) and glycine(G)
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what does GTP stand for?
Guanosine Triphosphate
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what attaches to the Nuclear import receptor to release the protein
Ran GTP
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what attaches to Ran GTP to release nuclear import receptor?
Ran Binding protein
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what attaches to Ran binding protein to hydrolyse GTP -> GDP?
GTPase Activating protein (GAP)
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What binds to Ran binding protein to release GDP ?
Guanosine nucleotide exchange factor (GEF)
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what happens to the Ran-GDP ?
Diffuses back across the nuclear pore complex
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what do mRNA use to allow transport across nuclear export receptor?
Adaptor Proteins
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when can Adaptor proteins bind to mRNP
When mRNA has been correctly modified and has 5' cap
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IMPORTANT - what is the name of the adaptor protein to transport mRNA across NPC?
NXF-1
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Once mRNP has be exported via NPC, what binds to release mRNP?
ATPase binds and hydrolysis to ADP causes modification to MRNA and it is released.
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What occurs in the nucleolus?
Ribosome synthesis
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what gives the nucleolus its dark appearance?
high concentration of Proteins and RNA's
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what are the TWO subunits of a ribosome?
60s and 40s ribosomal subunit
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what is the 60s ribosomal subunit composed of?
28s , 5s and 5.8s + 49 proteins
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what is the 40s ribosomal subunit composed of?
18s + 33 proteins
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how many rRNA genes code for the 4 rRNA's
Over 200 genes
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How are the rRNA genes located on a DNA sequence
Clustered together in Tandem Repeats
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How many chromosomes contain rRNA genes
6 chromosomes
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What type of enzyme transcribes rRNA
RNA Polymerase
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what is RNA Polymerase I Responsible for?
Transcription of 18s, 5.8s and 28s rRNA
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what is RNA Polymerase III Responsible for?
Transcription of 5s rRNA
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where is 5s RNA transcribed?
outside of the nucleolus inside the nucleus
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what is the region that gets transcribed before modification?
45s pre-rRNA
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what is added to the 45s pre-rRNA after its been transcribed
Ribosomal Proteins are added
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What is the name of the rRNA region after the addition of proteins
90s Pre-Ribosome
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what molecule undergoes the modification of rRNA's
snoRNPS (Small nucleolar RNA's )
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what are snoRNPS?
non-coding RNA molecules which contain proteins and enzyme enabling modification.
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what is the 1st modification of rRNA via snoRNPS
Methylation of hydroxyl group on ribose sugar
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what is the 2nd modification of rRNA via snoRNPS
conversion of uridine to pseudouridine (isomorisation reaction)
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what is the 3rd modification of rRNA via snoRNPS
Cleavage of non-coding spacer regions of 45s pre-rRNA
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Why do we think modifications of rRNA occurs
allows activation of translation of occur?
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what enzymes are responsible for the removal of nucleotides from the external transcribed spacers (ETS)
Exoribonucleases
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what enzymes are responsible for the removal of nucleotides from the Internal transcribed spacers (ITS)
Endoribonucleases
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what molecule transports the enzymes responsible for spacer region removal?
snoRNPS
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what method of transport across NPC do Ribosomes require
Ran-GTP, Nuclear Export receptors
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Card 2

Front

how many total proteins make up each nuclear pore complex?

Back

500 - 1000

Card 3

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what is the name of the proteins within nuclear pore complex?

Back

Preview of the front of card 3

Card 4

Front

roughly how many nuclear pore complex's are in a mammalian cell?

Back

Preview of the front of card 4

Card 5

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what size does a molecule need to be to freely diffuse across the NPC?

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