Unit 1

Question 1

Nuclear Envelope

Answer 1

1.) Inner & Outer nuclear membranes
2.) Nuclear Lamina; Fibrous network
3.) Nuclear pore complexes; channels through which molecules can travel between nucleus & cytoplasm

Question 2

Lamins

Answer 2

• Compose nuclear lamina
• Phosphorylation / dephosphorylation of lamins controls integrity of nuclear lamina

Question 3

Emerin

Answer 3

• Lamin-binding protein

Question 4

GEF

Answer 4

• Guanine nucleotide exchange factor
• Needed for binding of GTP

Question 5

GAP

Answer 5

• GTPase activating protein
• Needed for hydrolysis of GTP to GDP (inactivation)

Question 6

NLS

Answer 6

• Nuclear localisation signal
• Found in certain proteins, lets them bind to an NLS receptor

Question 7

Importin α / β

Answer 7

1.) Bind to proteins w/ NLS
2.) Associates w/ cytoplasmic filaments
3.) Passes through NPC

Question 8

Ran

Answer 8

• GTPase
• Binds to protein-importin complex
• Forms Ran*GTP-importin β complex
• Transported back to cytoplasm where Ran*GTP is converted to Ran GDP, & is brought back to nucleus

Question 9

Exportin

Answer 9

• Transports importin α back to cytoplasm

Question 10

Chromatin

Answer 10

• Complexes of eukaryotic DNA & proteins
• Contains ~2x as much protein as DNA
• Major proteins of chromatin are histones

Question 11

Histones

Answer 11

• Small proteins containing high proportion of basic amino acids

Question 12

Cohesin

Answer 12

• Stabilize supercoiled loops of higher-ordered structures of chromatin

Question 13

Euchromatin

Answer 13

• Return to a dispersed state after mitosis

Question 14

Heterochromatin

Answer 14

• Condensed during interphase
• Constituative Heterochromatin
  a.) Always condensed
  b.) Mostly found around centromeres & telomeres
  c.) Consists of highly repeated sequences & few games
• Facultative Heterochromatin
  a.) Inactivated during certain phases of the organism’s life (X-inactivation)

Question 15

Flavoproteins

Answer 15

• Contain NAD+, FAD+ prosthetic groups
• Compose complexes 1/2 in ETC
• Pass e- to Ubiquinone

Question 16

Ubiquinone (Coenzyme Q)

Answer 16

• Only carrier not to associate with a protein
• e- derived from NADH / FADH2 passed to ubiquinone (lipid soluble)
• e- then transferred to complex 3 (cytochrome c)

Question 17

Cytochromes

Answer 17

• Contain heme prosthetic groups Fe3+ → Fe2+
• e- passed here from ubiquinone
• Carries e- to complex 4

Question 18

Copper-contain proteins

Answer 18

• Cu2+ → Cu+