3: Nonenzymatic Protein Function and Protein Analysis

Question 1

List the structural proteins

Answer 1

1) collagen
2) elastin
3) keratins
4) actin
5) tubulin

Question 2

________ generally have highly repetitive secondary structure and a supersecondary structure.

Answer 2

Structural proteins

Question 3

A repetitive organization of secondary structural elements together sometimes referred to as a ________

Answer 3

Motif

Question 4

______ has a characteristic trihelical structure (three-left handed helices woven together to form a secondary right-handed helix)

Answer 4

Collagen

Question 5

________ makes up most of the extracellular matrix of connective tissue.
It is found throughout the body and is important in providing strength and flexibility.

Answer 5

Collagen

Question 6

_____________ :
-another important component of the extracellular matrix of connective tissue

-primary role is to stretch and then recoil like a spring, which restores the original shape of the tissue

Answer 6

Elastin

Question 7

___________:

• intermediate filament proteins found in epithelial cells
• contribute to the mechanical integrity of the cell and also function as regulatory proteins.
• primary protein that makes up hair and nails

Answer 7

Keratin

Question 8

_______:

• protein that makes up microfilaments and thin filaments in myofibrils
• it is the most abundant protein in eukaryotic cells
• have a positive side and a negative side; this polarity allows motor proteins to travel unidirectionally along an actin filament

Answer 8

Actin

Question 9

__________:

-protein that makes up microtubules

Also has polarity: the negative end of a microtubule is usually located adjacent to the nucleus, whereas the positive end is usually in the periphery of the cell

Answer 9

Tubulin

Question 10

List the roles of microtubules

Answer 10

• providing structure
• chromosome separation in mitosis and meiosis
• intracellular transport w/kinesin and dynein

Question 11

Motor proteins also display enzymatic activity, acting as _______ that power the conformational change necessary for motor function.

Answer 11

ATPases

Question 12

_________ proteins are responsible for muscle contraction and cellular movement.

Answer 12

Motor

Question 13

______ primary motor protein that interacts with actin

Answer 13

Myosin

Question 14

In addition to its role as the thick filament, ____ can be involved in cellular transport.

Answer 14

Myosin

Question 15

Describe the myosin subunit

Answer 15

Has a single head and neck; movement at the neck is responsible for the power stroke of the sarcromere contraction

Question 16

Name the motor proteins associated with microtubules

Answer 16

Kinesin and dyneins

Question 17

Describe the structure of lonesome and dyneins.

Answer 17

They have two heads, at least one of which remains attached to tubulin at all times.

Question 18

__________ play key roles in aligning chromosomes during metaphase and depolarizing microtubules during anaphase of mitosis.

Answer 18

Kinesics

Question 19

___________ are involved in the sliding movement of cilia and flagella.

Answer 19

Dyneins

Question 20

Both proteins are important for vesicles transport in the cell, but have opposite polarities:

_______ bring vesicles toward the positive end of the microtubules

_______ bring vesicles toward the negative end

Answer 20

Kinesics, dyneins

Question 21

_________ bring vesicles of neurotransmitter to the positive end of the axonal microtubules (toward the synaptic terminal).

Answer 21

Kinesins

Question 22

______bring vesicles of waste or recycled neurotransmitter back toward the negative end of the microtubule (toward the soma) through retrograde transport.

Answer 22

Dyneins

Question 23

_________ move along microtubules in a stepping motion such that one or both heads remain attached at all times.

Answer 23

Kinesins

Question 24

Describe binding proteins. Give examples.

Answer 24

• Proteins that have stabilizing functions in individual cells.
• They transport/sequester molecules by binding to them.
• each binding protein has an affinity curve for its molecule of interest

-curve differs depending on the goal of the binding protein
(When sequestration of a molecule is the goal, the binding protein usually has high affinity for its target across a large range of concentrations so it keep it bound at nearly 100)

Examples: hemoglobin, calcium-binding protein, DNA-binding proteins

Question 25

____________ are proteins found on the surface of most cells and aid in binding the cell to the extra cellular matrix or other cells.

Answer 25

Cell Adhesion Molecules (CAMs)

Question 26

While there are a number of different types of CAMs, they are all _____________.

Answer 26

Integral membrane proteins

Question 27

What are the 3 categories of adhesion molecules?

Answer 27

1) cadherins
2) integrins
3) selectins

Question 28

Describe cadherins

Answer 28

• type of CAM
• group of glycoproteins that mediate calcium-dependent cell adhesion.
• often hold similar cell types together (such as epithelial cells)
• different cells usually have type-specific cadherins (epithelial cells use E-cadherin while nerve cells use N-cadherin)

Question 29

Describe integrins

Answer 29

• type of CAM
• group of proteins that all have two membrane-spanning chains called alpha and beta.
• play a very important role in cellular signaling
• can greatly impact cellular function by promoting cell division, apoptosis, etc.
• others are used for WBC migration, stabilization of epithelium on its basement membrane, etc

Question 30

Integrins have a group of proteins that all have two membrane-spanning chains called alpha and beta. What are the significance of these chains?

Answer 30

These chains are very important in binding to and communicating with the extra cellular matrix.

Question 31

_______ are unique because they bind to carbohydrate molecules that project from other cell surfaces.

How strong are these bonds?

Answer 31

Selectins

These bonds are the weakest bonds formed by the CAMs.

Question 32

________ are expressed on WBC and the endothelial cells that line the blood vessels.

Answer 32

Selectins

Question 33

Like integrins, _______ play an important role in host defense, including inflammation and WBC migration.

Answer 33

Selectins

Question 34

The most prominent type of protein found in the immune system is the _______.

Answer 34

Antibody

Question 35

___________ are proteins produced by B-cells that function to neutralize targets in the body (toxins and bacteria) and then recruit other cells to help eliminate the threat.

Answer 35

Antibodies

Question 36

What is another name for antibodies?

Answer 36

Immunoglobulins (Ig)

Question 37

Describe the structure of antibodies

Answer 37

Y-shaped proteins that are made up of