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Cell biology > Intracellular compartments (Sept 19) > Flashcards

Intracellular compartments (Sept 19) Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What percentage of a cell volume is cytosol?

A

~50%

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2
Q

What percentage of a cell volume is cytosol?

A

~20%

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3
Q

The majority of cell membrane (by percentage, intra and extracellular) is taken up by _______, followed by ________, followed by ________.

A

Endoplasmic Reticulum
mitchondrial inner membrane
Golgi apparatus

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4
Q

There are some general trends in compartment size, why is it a bad idea to rely on any of these trends.

A

Because the cell will vary how much of each organelle it has based on its function and size.

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5
Q

What is the theory for the evolution of the nucleus?

A

That it began as an invagination of the cell membrane, which later closed off and stayed within the cell.

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6
Q

What is the theory for the evolution of the endoplasmic reticulum?

A

It developed out of the nuclear membrane. Indeed the extracellular nuclear membrane is continuous with the endoplasmic reticulum.

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7
Q

Describe the nuclear membrane.

A

It is has multiple nuclear pores, and is a fluid containing organ, like the endoplasmic reticulum. Indeed it is continuous with the endoplasmic reticulum.

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8
Q

What gives each organelle its unique activity?

A

The unique proteins it possesses.

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9
Q

How many proteins does the average Eukaryotic cell have within it?
How many different varieties?

A

~10^10

~10,000

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10
Q

Give to examples of organelles which maintain an electrochemical gradients across their bilayer.

A

ER: Ca2+
Mitochondria: H+

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11
Q

What are the three methods of protein trafficking within the cell?

A
  • Vesicular transport
  • Transmembrane transport
  • Gated transport
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12
Q

Describe vesicular transport.

A

Vesicular transport is always between topologically equivalent areas.

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13
Q

ER has vesicular transport to?

A

Peroxisome and the Golgi.

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14
Q

Golgi has vesicular transport to?

A

ER, secretory vesicles, endosomes, early and late, cell exterior.

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15
Q

What is budding and fusing in vesicular transport?

A

budding: vesicle just beginning to leave a membrane surface.
fusing: A vesicle which is combining with a membrane surface.

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16
Q

Define transmembrane transport of proteins.

A

Movement through translocator channels across membranes. Moves into a topologically distinct department.

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17
Q

How does protein movement through a translocator channel differ from movement through a gated channel?

A

A protein must unwind and be fed through a translocator protein as a strand of amino acids, then it refolds on the other side. Gated channels can transport folded proteins through them.

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18
Q

Transmembrane transport normally moves proteins from within the ______, to within an ______ compartment.
Name three examples of transmembrane transport.

A

cytosol
intracellular

Cytosol–>mitochondria
Cytosol–>chloroplast
Cytosol–>ER

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19
Q

Has transmembrane transport been seen in the PM?

A

I don’t know… he doesn’t say. But the slides implied this isn’t known yet.

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20
Q

What are sorting signals?

A

They are areas of a protein which can be recognized and bound by specific receptors. Sorting signals essentially tell where to send the protein.

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21
Q

What are the two types of sorting signals?

A

Signal sequences: linear sequence of amino acids, generally at the Carboxyl or amino end of the protein.
Signal patches: little separated amino acid sequences which will line up once the protein has been folded, they will be recognized by receptors.

22
Q

What is a signal patch or sequence analogous too?

A

An address on a postal letter.

23
Q

Name three types of cells with no nucleus in animals.

A

Platelets
RBCs (accept in birds, reptiles)
Some cells in the lens of the eye

24
Q

What cell type can have multiple nuclei in animals?

A

Skeletal muscle fibers.

25
Q

What is the lumen between the two membranes of the nucleus?

A

Perinuclear space. It is continuous with the ER lumen.

26
Q

What are nuclear lamina?

A

Intermediate fibers which form a matrix on the intra nuclear side of the nucleus.

27
Q

Define Nucleoporins:

A

any protein which is a part of the nuclear pore complex.

28
Q

How many nucleoporins are in each nuclear pore complex?

A

500-1000

29
Q

Cytosolic fibrils:

A

Are repeating phenyl-alanine (F), and glycine (G). They reach out into the cytosolic place and are thought to bring in proteins via nuclear receptors (which will bind to their signal sequence).

30
Q

How does the nuclear pore sit in the nuclear membrane?

A

The poor must be reacting with the hydrophillic head groups only, because the membrane curls around at the pore.

31
Q

Can small molecules diffuse freely through nuclear pores?

What size must these molecules be?

A

yes if they are ~9 nM

32
Q

Can large molecules freely diffuse into the nucleus?

A

No, they must be actively, selectively moved.

33
Q

Define
nuclear-resident proteins:
Transcription Factor Proteins:

A

nuclear-resident proteins: These are proteins which are meant to reside in the nucleus, they must be transferred there from the cytosol were they were synthesized.

Transcription Factor Proteins: Enter the nucleus to bind DNA, change function.

34
Q

Name three types of molecules that must be able to enter and exit the nucleus.

A

Nuclear-resident proteins. (in)
Transcription factors. (in)
mRNA (out

35
Q

Where does a nuclear import signal send you to?

A

It sends you to the nucleus… without it the protein will not be able to enter.

36
Q

______ where used to visualize protein transport into the nucleus.

A

Colloidal gold spheres

37
Q

Why does protein tagging with colloidal gold spheres allow visualization of the protein?

A

Because gold will appear opaque on an electron microscope.

38
Q

Nuclear import receptor.

A

There is a variety of nuclear import receptors. They bind proteins with distinct nuclear localization signals.

39
Q

Nuclear import adaptor protein does what?

A

It binds to a protein with a unique signal sequence, and then binds to a nuclear import receptor.

40
Q

G-proteins are a nickname for proteins which do what?

A

That bind and hydrolyze GTP. This gives them a switch like protein.

41
Q

Do G proteins have GTPase activity?

Do they act as molecular switches?

A

Yes.

Yes.

42
Q

What are downstream effector proteins?

A

They are proteins that result from the signal cascade caused by G proteins.

43
Q

Generally, in what conformation must a G protein be in to interact with a downstream effector protein.

A

It must be bounded to GTP (not GDP, GTP). GTP GTP.

44
Q

GAPs stands for?

A

GTPase-accelerating proteins

45
Q

GEFs stands for?

A

Guanine nucleotide-Exchange Factors.

46
Q

What do GAPs do?

A

Well since they are called GTPase accelerating proteins we can correctly assume they increase the rate at which GTP is hydrolyzed. GTP–>

47
Q

What do GEFs do?

A

Guanine nucleotide-exchanger factors, enable the G protein to release GDP.

48
Q

Are GAPs and GEFs specific for specific types of G proteins?

A

Yes. There is generally specificity in this system. With one type of G-protein having one type of GAP and GEF to help it catalyze.

49
Q

Why is GAP necessary?

A

Because while G proteins are already hydrolytic enzymes (GTPases), the are GTPases with very low catalytic efficiencies. Therefor they need GAP.

50
Q

What are the two main types of G-proteins?

A

Heterotrimeric G proteins

Monomeric G proteins

51
Q

You stopped right before RAS. Make sure you cover RAS on your next series of slides.

A

DO IT!!!!!!!

Cell biology (27 decks)

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