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Biochemistry > Non-enzymatic protein function > Flashcards

Non-enzymatic protein function Flashcards

1
Q

A cell cytoskeleton is composed of several different types of protein fibers namely?

A

Microfilaments, intermediate filaments, and microtubules

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2
Q

Actin is a microfilament. What is its functions?

A

Motion, structure, cell division, and muscle contraction

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3
Q

Individual actin monomers are known as

A

G actin (have a globular shape)- each is a protein an d have sites where and ADP and ATP can bind

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4
Q

G actin bind to each other to form what?

A

Filamentous actin (F-actin)

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5
Q

How many F-actin are stuck together to form a microfilament?

A

2

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6
Q

2 ends of actin

A
  1. Plus end heavy in ATP bound actin

2. Minus end heavy in ADP bound actin

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7
Q

Which end of the actin is most likely to have beads dissociate

A

ADP bound end

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8
Q

Treadmilling

A

When actin filament simultaneously grow at one and and shrinks on the other end. A process derived by ATP hydrolysis

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9
Q

What can be used to block addition or removal of monomeric actin

A

Capping end

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10
Q

These are composed of various types of protein subunits and are generally more stable and do not bind nucleotides like the other 2 classes of cytoskeleton fibers

A

Intermediate filaments

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11
Q

These can be stretched like a rubber band. they are typically found in the cytoplasm between the nucleus and plasma membrane

A

Intermediate filaments

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12
Q

Their main function is structural support and helps cell adhere to neighboring cells and in positioning organelles

A

Intermediate filaments

Ex. Keratin

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13
Q

These provides structural support for cilia and eukaryotic flagella, chromosome separation during mitosis and meiosis, and intracellular support

A

Microtubules

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14
Q

The largest of the cytoskeleton fibers and is composed of a diner of an alpha-tubulin and a beta-tubulin

A

Microtubules

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15
Q

Microtubule dimers have nucleotide binding sites for ?

A

GTP and GDP

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16
Q

Polymerization of microtubule dimers are driven by

A

Large number of dimers in the cell

*think Le Chatelier’s principle

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17
Q

Polymerization and Depolymerization preferentially occurs at which end of microtubules?

A

Positive end

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18
Q

Presence of GDP at the positive end of the microtubules favor polymerization or depolymerization?

A

Depolymerization

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19
Q

Motor proteins functions

A
  1. Transport
  2. Motility in unicellular organisms
  3. Generating force during muscle contraction
20
Q

These motor proteins are ATP-ashes which consumes energy from ATP hydrolysis. They can also do anterograde cargo transport

A

Kinesins

21
Q

Kinesics move through the (positive / negative) end of the microtubule, which faces the periphery of the cell

A

Positive

22
Q

Kinesins are made up of how many subunits? Describe them

A

4- heterotetramer

  1. 2 heavy chains and 2 head groups attached to thin flexible stocks
  2. 2 light chains on top to which the cargo that the kinesin is transporting attaches to.
23
Q

Kinesins attach to which protein fiber. What drives this mechanism?

A

It attaches to microtubule and ATP hydrolysis is used to push movement of the Kinesins to the positive end

24
Q

Which motor protein walk towards the minus end of microtubules (retrograde transport)- towards the cell center

A

Dyneins

25
Q

2 main groups of dyneins

A

Axonemal and cytoplasmic

26
Q

This type of dyneins are only found in cell with cilia or flagella. They can help generate the sliding motion between microtubules that are necessary for these structures to move

A

Axonemal

27
Q

This type of dyneins transport cargo for cell functions such as organelle and vesicle components

A

Cytoplasmic

28
Q

This type of motor proteins are also ATP-ase and attaches to actin filaments during muscle contraction

A

Myosins

29
Q

Myosin’s structure and function of each

A
  1. Head motor domain- binds actin and hydrolyzes ATP to power myosin’s movement
  2. neck- linker region that hold the structure together
  3. tail effector domain- binds to cargo or other myosin molecules
30
Q

These are proteins located on the cell surface or periphery that glue cells together to stabilize tissues and organs

A

Cell Adhesion Molecules (CAM)

31
Q

Different functions of different types of CAMs

A
  1. Associate with cytoskeletal elements to help the cytoskeletons stay in place
  2. Anchor cells to each other and the extra cellular matrix
32
Q

This type of CAM mediate the inflammatory response and are important in blood clotting

A

Selectins

33
Q

Where are selectins found?

A

Immune cells, platelets, and endothelial cells lining blood vessels

34
Q

Selectin binding is which ion dependent?

A

Calcium-ion dependent

*also heterophilic

35
Q

This CAM plays a role in cell growth and development. They are calcium-ion dependent and play major role in cell adhesion

A

Cadherins

36
Q

Cadherins bind to other Cadherins which makes it?

A

Homophilic

37
Q

Type of CAM that are membrane-spanning heterodimers with alpha and beta subunits and ligand binding sites that attract metal ions and proteins

A

Integrins

38
Q

This type of CAM helps cell adhere to this extracellular matrix by linking microfilaments in the cytoskeleton to the matrix proteins outside of the cell

A

Integrins

39
Q

This type of CAM play a role in cell signaling by binding ligands and interacting with various receptors on the cell surface

A

Integrins

40
Q

3 types of cell junctions

A

Anchoring junctions, gap junctions, and tight junctions

41
Q

This junction connects one cell with the cytoskeleton of other cells or with the extracellular matrix- helps stabilize cells an tissues

A

Anchoring junctions

42
Q

Adherens junctions created by cadherin proteins to interact with actin filaments and desmosomes are what type of junctions

A

Anchoring junction

43
Q

Desmosomes tend to be found in cells that have to withstand a lot of force regularly such as heart muscle. The cadherin proteins attach to what protein fibers?

A

Intermediate filaments

44
Q

Gap junctions are connected by which proteins

A

Connexin

45
Q

T or F. The connexin proteins connect cells in such a way that there’s a small passage between them through which small ions can diffuse

A

TRUE

46
Q

What ions can pass through gap junctions

A

Sugars, vitamins, nucleotides, and amino acids, cAMP, and Ca2+

Biochemistry (6 decks)

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