Lecture 8: Intracellular Compartments and Protein Sorting Flashcards Preview

BIOC 341 > Lecture 8: Intracellular Compartments and Protein Sorting > Flashcards

Flashcards in Lecture 8: Intracellular Compartments and Protein Sorting Deck (80)
Loading flashcards...
1

3 features of cellular compartmentalization?

-segregation of metabolic function -organelle-specific environments -membrane surfaces

2

Segregation of metabolic function

-glycolosis in cytoplasm -Krebs cycle in mitochondria

3

Organelle-specific environments

-redox potential in ER -changing PH in ER -acidic PH of lysosomes -glycosylation reactions in the ER and golgi

4

Membrane surfaces

-lipid synthesis -PH gradients and ATP production

5

What are the three types of transport between compartments?

-gated transport -transmembrane transport -vesicular transport

6

Identify the type of transport in red

gated transport

7

Identify the type of transport in blue

Transmembrane transport

8

Identify the type of transport in green

vesicular transport

9

How does a protein “know” where to go? 

Specific elements of a protein, mostly primary amino acid sequence, direct protein traffic 

– Signal sequences 

– Signal patches 

10

What signal sequence is this?

import into nucleus

11

What signal sequence is this?

Return to ER

12

What signal sequence is this?

Import into mitochondria

13

What signal sequence is this?

Import into plasmid

14

What signal sequence is this?

import into peroxisomes

15

What signal sequence is this?

Import into ER

16

What signal sequence is this?

Return to ER

17

Gated transport occurs___

from the cytoplasm to the nucleus

18

The nuclear envelope is directly connected to the ___

ER

19

Nuclear pore complex

>125 MegaDaltons 

>30 proteins (nucleoporins) 

~3,000-4,000 NPCs per nucleus 

20

• Molecules less than ____ Da freely diffuse through the NPC

5,000

21

 Protein between _____ Da diffuse through more slowly proportional to their size 

20-60,000

22

Proteins greater than ___ Da require help to enter

60,000

23

How do “big” proteins enter and exit the nucleus?

• They use a regulated (gated) pathway that relies on specific import signals or nuclear localization signals 

24

• Nuclear localization signals (NLSs) bind to...

specific receptor proteins that direct import into the nucleus through the NPC 

25

The nuclear localization signal (NLS) was identified by systematically deleting or modifying sequences in _____

SV40 T-antigen 

26

A change as small as ___ can disrupt the activity of an NLS 

one amino acid

27

Functionality as an NLS is ___ its location within the polypeptide 

independent of

28

___ bind NLSs and nucleoporins

Nuclear import receptors

29

Nuclear import receptors are a family of related protein called ____ or ____

importins or karyopherins

30

These protein bind “cargo” via the NLS in the cytosol and then bind to the NPC 

nuclear import receptors (importins)