The Nucleus

Question 1

Prokaryotic Nucleus

Answer 1

Nucleoid
Free ribosomes
No endomembrane system
No mitochondria
Small

Question 2

Eukaryotic Nucleus

Answer 2

Enclosed nucleus
Free ribosomes and rough ER
Vast interconnected endomembrane system
mitochondria/chloroplast
larger

Question 3

Do Pro or eukaryotes have a membrane bound nucleus
- nuclear envelope
- nuclear pores

Answer 3

Eukaryotes

Question 4

True or False the Nucleus is the smallest organelle

Answer 4

False it is the largest organelle

Question 5

Nucleus Function

Answer 5

• Compartmentalization of the cellular genome and its activities
• site of DNA replication, transcription and RNA processing
• where translation components are synthesized
• coordination of cellular activities
• control of metabolism, protein synthesis, cell division

Question 6

Outer membrane function of the nuclear envelope

Answer 6

binds ribosomes and is continuous with RER

Question 7

Inner membrane function of the nuclear envelope

Answer 7

has a unique protein composition which connect to nuclear lamina

Question 8

function of the nuclear envelope

Answer 8

separate nuclear contents from cytoplasm
separate genome from cytosol and transcription from translation
it is a selective barrier so it regulates passage of molecules between the nucleus and cytosol
regulates gene expression and composition of nucleus

Question 9

what is the structure that is a thin meshwork of long filament like proteins

Answer 9

nuclear lamina

Question 10

where is the nuclear lamina located

Answer 10

on the inner surface of the nuclear envelope (bound to it)

Question 11

nuclear laminas function

Answer 11

scaffold for chromatin attachment
support structure of nuclear envelope

Question 12

what are interchromosomal channels

Answer 12

regions between domains that serve as barriers to prevent unwanted DNA-DNA and or DNA-protein interactions

Question 13

What are Transcription Factories

Answer 13

chromatin from different subdomains extending into interchromosomal channels
where transcription factors are concentrated

Question 14

What are nuclear speckles

Answer 14

subdomains where mRNA splicing factors are concentrated
they can move quickly and grow/shrink depending on needs of the cell

Question 15

where are nuclear speckles located

Answer 15

in interchromosomal channels next to transcription factories

Question 16

What is the nucleolus structure

Answer 16

dense and granular in appearance
not membrane bound
size depends on metabolic activity of the cell

Question 17

what does an increase in cellular activity have to do with protein synthesis, size and number

Answer 17

an increase in cellular activity = increase in protein synthesis = increase in size and number of nucleoli

Question 18

What is the function of Ribosome Biogenesis

Answer 18

site of ribosomal DNA gene transcription and rRNA processing
Initial stage of rRNA and protein assembly (final assembly is in the cytosol)

Question 19

What are nuclear pores

Answer 19

gateway between cytoplasm and nucleoplasm (3/4000 pores per nucleus)

Question 20

Describe the structure of the Nuclear Pore Complex

Answer 20

It is the protein structure which fills the nuclear pore
extends into the cytoplasm and the nucleoplasm

Question 21

FG nucleoporins (NUPs)

Answer 21

unusual amino acid composition - containing a large number of phenylalanine-glycine repeat sequences (FG domains)

Question 22

FG domains structure

Answer 22

extended and flexible organization
extend into the central channel
form a hydrophobic mesh to limit diffusion of macromolecules larger than 40 kDa

Question 23

where are NUPs

Answer 23

on the cytoplasmic and nuclear side of the nuclear pore complex
linked to the central scaffold and cytoplasmic filaments or basket

Question 24

what are cytoplasmic fliaments

Answer 24

long protein filaments that extend into the cytosol (cytosolic side) and are involved in nuclear receptor cargo protein recognition and import of the nuclear basket

Question 25

what is the nuclear basket structure and function

Answer 25

located on nuclear side of the NPC and is involved in nuclear receptor cargo protein import and export